RESUMEN

Bariatric surgery (BS) is considered the most effective intervention for patients with severe obesity and is used to maintain long-term weight loss and glycemic control. The aim of this study was to analyze the effects of genotypes and haplotypes of the fat mass and obesity-associated (FTO) and melanocortin 4 receptor (MC4R) genes on total body weight loss (TBWL), post-surgery weight, and post-BMI after bariatric surgery. We retrospectively selected 101 patients from Bajio High Specialty Regional Hospital, León Guanajuato, México, who underwent Roux-en-Y gastric bypass (RYGB) to determine their body mass index (BMI), blood pressure, biochemical characteristics, and comorbidities. Post-surgery, patients were referred for registered anthropometry and blood pressure. Glucose, lipid and hepatic profiles, and insulin, leptin, and ghrelin levels were measured, and rs9939609, rs9930506, and rs1421085 FTO and rs17782313 MC4R polymorphisms were genotyped. Six (4-8) years after BS, post-surgery weight was greater in carriers of the rs9939609 and rs1421085 risk genotypes. TBWL was lower for the rs9930506 and rs1421085 risk genotypes. Insulin and HOMA-IR were greater in patients with the three FTO polymorphisms. There were significant interaction effects of the rs9930506 and rs1421085 FTO risk genotypes on weight and BMI in response to BS. No association was found with the MC4R polymorphism. The genotypes and haplotypes of the FTO gene influence post-surgery weight, TBWL, insulin levels, and HOMA-IR.

Asunto(s)

Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato , Cirugía Bariátrica , Índice de Masa Corporal , Polimorfismo de Nucleótido Simple , Receptor de Melanocortina Tipo 4 , Pérdida de Peso , Humanos , Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato/genética , Receptor de Melanocortina Tipo 4/genética , Masculino , Femenino , Adulto , Pérdida de Peso/genética , Persona de Mediana Edad , Obesidad Mórbida/cirugía , Obesidad Mórbida/genética , Estudios Retrospectivos , Haplotipos , Genotipo

RESUMEN

Polymorphisms in genes of leptin-melanocortin and insulin pathways have been associated with obesity and type 2 diabetes. We hypothesized that polymorphisms in IRS1, IRS2, MC3R, and MC4R influence metabolic and inflammatory markers and food intake composition in Brazilian subjects. This exploratory pilot study included 358 adult subjects. Clinical, anthropometric, and laboratory data were obtained through interview and access to medical records. The variants IRS1 rs2943634 A˃C, IRS2 rs1865434 C>T, MC3R rs3746619 C>A, and MC4R rs17782313 T>C were analyzed by real-time polymerase chain reaction. Food intake composition was assessed in a group of subjects with obesity (n = 84) before and after a short-term nutritional counseling program (9 weeks). MC4R rs17782313 was associated with increased risk of obesity (P = .034). Multivariate linear regression analysis adjusted by covariates indicated associations of IRS2 rs1865434 with reduced low-density lipoprotein cholesterol and resistin, MC3R rs3746619 with high glycated hemoglobin, and IRS1 rs2943634 and MC4R rs17782313 with increased high-sensitivity C-reactive protein (P < .05). Energy intake and carbohydrate and total fat intakes were reduced after the diet-oriented program (P < .05). Multivariate linear regression analysis showed associations of IRS2 rs1865434 with high basal fiber intake, IRS1 rs2943634 with low postprogram carbohydrate intake, and MC4R rs17782313 with low postprogram total fat and saturated fatty acid intakes (P < .05). Although significant associations did not survive correction for multiple comparisons using the Benjamini-Hochberg method in this exploratory study, polymorphisms in IRS1, IRS2, MC3R, and MC4R influence metabolic and inflammatory status in Brazilian adults. IRS1 and MC4R variants may influence carbohydrate, total fat, and saturated fatty acid intakes in response to a diet-oriented program in subjects with obesity.

Asunto(s)

Diabetes Mellitus Tipo 2 , Adulto , Humanos , Proyectos Piloto , Diabetes Mellitus Tipo 2/genética , Polimorfismo de Nucleótido Simple , Brasil , Obesidad/genética , Obesidad/metabolismo , Ingestión de Alimentos , Carbohidratos , Ácidos Grasos , Receptor de Melanocortina Tipo 4/genética , Receptor de Melanocortina Tipo 4/metabolismo , Proteínas Sustrato del Receptor de Insulina/genética , Proteínas Sustrato del Receptor de Insulina/metabolismo , Receptor de Melanocortina Tipo 3/genética , Receptor de Melanocortina Tipo 3/metabolismo

RESUMEN

OBJECTIVE: We sought to assess body mass index trajectories of children with genetic obesity to identify optimal early age of onset of obesity (AoO) cut-offs for genetic screening. STUDY DESIGN: This longitudinal, observational study included growth measurements from birth onward of children with nonsyndromic and syndromic genetic obesity and control children with obesity from a population-based cohort. Diagnostic performance of AoO was evaluated. RESULTS: We describe the body mass index trajectories of 62 children with genetic obesity (29 nonsyndromic, 33 syndromic) and 298 controls. Median AoO was 1.2 years in nonsyndromic genetic obesity (0.4 and 0.6 years in biallelic LEPR and MC4R; 1.7 in heterozygous MC4R); 2.0 years in syndromic genetic obesity (0.9, 2.3, 4.3, and 6.8 years in pseudohypoparathyroidism, Bardet-Biedl syndrome, 16p11.2del syndrome, and Temple syndrome, respectively); and 3.8 years in controls. The optimal AoO cut-off was ≤3.9 years (sensitivity, 0.83; specificity, 0.49; area under the curve, 0.79; P < .001) for nonsyndromic and ≤4.7 years (sensitivity, 0.82; specificity, 0.37; area under the curve, 0.68; P = .001) for syndromic genetic obesity. CONCLUSIONS: Optimal AoO cut-off as single parameter to determine which children should undergo genetic testing was ≤3.9 years. In case of older AoO, additional features indicative of genetic obesity should be present to warrant genetic testing. Optimal cut-offs might differ across different races and ethnicities.

Asunto(s)

Pruebas Genéticas , Obesidad , Humanos , Niño , Índice de Masa Corporal , Edad de Inicio , Obesidad/epidemiología , Obesidad/genética , Heterocigoto , Receptor de Melanocortina Tipo 4/genética

RESUMEN

A complex web of causation is involved in adiposity, including environmental, social and genetic factors. We aimed to investigate associations between genetic factors such as ancestry and single nucleotide polymorphisms, and obesity-related traits in a sampled Brazilian population. A sample of 501 unrelated adults participating in 2013 at the longitudinal Pró-Saúde Study (EPS) in Rio de Janeiro, Brazil was selected. We analysed 46 AIM-InDels (insertion/deletion) as genetic ancestry markers and four single nucleotide polymorphisms located in the genes MC4R (rs17782313), FTO (rs9939609), FAIM2 (rs7138803) and BDNF (rs4074134), previously described as associated with obesity. The selected obesity-related markers were anthropometric parameters such as body mass index, waist circumference and waist-to-hip ratio, and body composition measurements namely body fat percentage, android fat mass and gynoid fat mass. The sample showed greater European ancestry (57.20%), followed by African (28.80%) and lastly Amerindian (14%). Our results suggest that the rs4074134 (BDNF) CC genotype was directly associated with gynoid fat mass, whereas body fat percentage, android fat mass and the anthropometric parameters seem not to be associated with neither ancestry nor the four polymorphisms in this population sample, most likely due to a stronger role of social, behavioural and environmental determinants.

Asunto(s)

Factor Neurotrófico Derivado del Encéfalo , Obesidad , Adulto , Humanos , Factor Neurotrófico Derivado del Encéfalo/genética , Brasil , Obesidad/genética , Obesidad/epidemiología , Genotipo , Índice de Masa Corporal , Polimorfismo de Nucleótido Simple/genética , Genómica , Predisposición Genética a la Enfermedad , Receptor de Melanocortina Tipo 4/genética , Proteínas de la Membrana/genética , Proteínas Reguladoras de la Apoptosis/genética , Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato/genética

RESUMEN

Loss-of-function mutations in melanocortin-4 receptor (MC4R) are the most common cause of monogenic obesity, a severe type of early-onset obesity. Our aim was to determine the prevalence of MC4R mutations in a cohort of 97 Argentinian children with early-onset obesity. We found two novel mutations (p.V52E and p.G233S) and estimated a prevalence of 2.1%. We investigated the pathogenicity of mutations in HEK293T cells expressing wild-type or mutant MC4R and found that both mutants exhibited reduced plasma membrane expression and altered agonist-induced cAMP responses, with no changes in basal activity. Besides, MC4R G233S mutant demonstrated an altered agonist-dependent inhibition of voltage-gated calcium channels type 2.2. Results using a Gαs protein inhibitor suggest that the G233S mutation could be recruiting a different G-protein signaling pathway. The identification of new mutations in MC4R and characterization of their functional impact provide tools for the diagnosis and treatment of monogenic obesity.

Asunto(s)

Obesidad Infantil , Receptor de Melanocortina Tipo 4 , Niño , Humanos , Estudios de Cohortes , Células HEK293 , Mutación , Receptor de Melanocortina Tipo 4/genética , Obesidad Infantil/genética , Argentina

RESUMEN

The loss of function melanocortin 4-receptor (MC4R) Ile269Asn mutation has been proposed as one of the most important genetic contributors to obesity in the Mexican population. However, whether patients bearing this mutation respond differently to weight loss treatments is unknown. We tested the association of this mutation with obesity in 1683 Mexican adults, and compared the response of mutation carriers and non-carriers to three different weight loss interventions: dietary restriction intervention, phentermine 30 mg/day treatment, and Roux-en-Y gastric bypass (RYGB) surgery. The Ile269Asn mutation was associated with obesity [OR = 3.8, 95% CI (1.5-9.7), p = 0.005]. Regarding interventions, in the dietary restriction group only two patients were MC4R Ile269Asn mutation carriers. After 1 month of treatment, both mutation carriers lost weight: -4.0 kg (-2.9%) in patient 1, and -1.8 kg (-1.5%) in patient 2; similar to the mean weight loss observed in six non-carrier subjects (-2.9 kg; -2.8%). Phentermine treatment produced similar weight loss in six carriers (-12.7 kg; 15.5%) and 18 non-carriers (-11.3 kg; 13.6%) after 6 months of pharmacological treatment. RYGB also caused similar weight loss in seven carriers (29.9%) and 24 non-carriers (27.8%), 6 months after surgery. Our findings suggest that while the presence of a single MC4R loss of function Ile269Asn allele significantly increases obesity risk, the presence of at least one functional MC4R allele seems sufficient to allow short-term weight loss in response to dietary restriction, phentermine and RYGB. Thus, these three different interventions may be useful for the short-term treatment of obesity in MC4R Ile269Asn mutation carriers.

Asunto(s)

Cirugía Bariátrica , Fentermina , Receptor de Melanocortina Tipo 4 , Adulto , Humanos , Mutación , Obesidad/genética , Obesidad/cirugía , Pérdida de Peso/genética , Receptor de Melanocortina Tipo 4/genética

RESUMEN

INTRODUCCIÓN: El sobrepeso y la obesidad se definen como una acumulación anormal o excesiva de grasa que puede ser perjudicial para la salud.1 En el caso de los adultos, la Organización Mundial de la Salud (OMS) define el sobrepeso a un Índice de Masa Corporal (IMC) igual o superior a 25, y a la obesidad a un IMC igual o superior a 30. En el caso de los niños de 5 a 19 años, el sobrepeso se define con un IMC para la edad con más de una desviación típica por encima de la mediana establecida en los patrones de crecimiento infantil de la OMS, y la obesidad es mayor que dos desviaciones típicas para dichos patrones. En algunos casos, la obesidad es causada por trastornos genéticos en la vía leptinamelanocortina, el sistema hipotalámico que controla el gasto de energía y la ingesta de alimentos. La hormona anorexígena leptina es secretada principalmente por el tejido adiposo y refleja las reservas de energía del cuerpo. La señalización de leptina hipotalámica conduce a la activación del receptor de melanocortina-4 (MC4R), lo que resulta en un mayor gasto de energía y saciedad. Cuando se altera esta señalización, los pacientes desarrollan hiperfagia y obesidad de aparición temprana. 1,2 En el estado de alimentación, la leptina estimula la producción de propiomelacortina (POMC), que es procesada por la pro proteína convertasa subtilisina y kexina tipo 1 (PCSK1) en péptidos de melanocortina (hormona estimulante de melanocitos α [α-MSH] y ß-MSH) que se unen y activan MC4R, por lo tanto reducir la ingesta de alimentos. Entre estos trastornos se destacan la deficiencia de POMC o PCSK1 y la deficiencia del receptor de leptina (LEPR) que se caracterizan por una obesidad severa que comienza a una edad temprana y se hereda con un patrón autosómico recesivo. TECNOLOGÍA: Setmelanotide (IMCIVREE™) es un agonista del receptor melanocortina-4 (MC4). Es un péptido cíclico de 8 aminoácidos análogo de la hormona estimuladora de melanocitos alfa ligando del receptor MC4 endógeno (α-MSH). Las hormonas reguladoras derivadas de la periferia (por ejemplo, la leptina) estimulan la expresión de α-MSH a través de POMC, que regula el hambre, la saciedad y el gasto de energía al unirse a los receptores MC4 en el hipotálamo. OBJETIVO: El objetivo del presente informe es evaluar rápidamente los parámetros de eficacia, seguridad, costos y recomendaciones disponibles acerca del empleo de setmelanotide para el tratamiento de la obesidad. MÉTODOS: Se realizó una búsqueda bibliográfica en las principales bases de datos tales como PUBMED, LILACS, BRISA, COCHRANE, SCIELO, EMBASE, TRIPDATABASE como así también en sociedades científicas, agencias reguladoras, financiadores de salud y agencias de evaluación de tecnologías sanitarias. Se priorizó la inclusión de revisiones sistemáticas, ensayos clínicos controlados aleatorizados, evaluación de tecnología sanitaria y guías de práctica clínica de alta calidad metodológica. RECOMENDACIONES: No se hallaron guías de práctica clínica actualizadas en Argentina y en el Mundo que recomienden la tecnología en la indicación evaluada. La guía de práctica clínica de la Asociación Estadounidense de Diabetes publicada en 2022 menciona la tecnología, aunque no la recomienda, entre las alternativas terapéuticas para el manejo y prevención de la obesidad y control de peso en pacientes con diabetes. CONCLUSIONES: La evidencia que sustenta la aprobación de comercialización de setmelanotide (IMCIVREE™) para el control crónico del peso en personas mayores de 6 años de edad con obesidad debida a la deficiencia de POMC, PCSK1 o LEPR por parte de las agencias regulatorias relevadas, se basa en un solo estudio de Fase III abierto y no controlado en pocos pacientes de países del hemisferio norte. Este estudio demostraría que setmelanotide, junto a medidas saludables, alcanzarían las metas de pérdida de peso propuestas en personas con obesidad severa al mediano plazo; sin embargo, esto no se traduciría en mejoras en estudios de laboratorio relevantes para el seguimiento y existe incertidumbre sobre su efecto en la calidad de vida reportada por estos pacientes. Las agencias regulatorias relevadas han autorizado recientemente la comercialización de setmelanotide en pacientes muy seleccionados mediante estudios genéticos, y bajo criterios de mantenimientos específicos. No se hallaron guías de práctica clínica actualizadas en Argentina y en el Mundo que recomienden la tecnología en la indicación evaluada. No se hallaron evaluaciones económicas publicadas, aunque el costo del fármaco es elevado.

Asunto(s)

Humanos , Receptor de Melanocortina Tipo 4/agonistas , Obesidad/tratamiento farmacológico , Argentina , Eficacia , Análisis Costo-Beneficio/economía

RESUMEN

A obesidade é definida pelo excesso de gordura corporal acumulada no tecido adiposo quando o indivíduo atinge valores de IMC igual ou superior a 30 Kg/m2. Constitui um dos principais fatores de risco para várias doenças não transmissíveis (DNTs) como por exemplo, diabetes mellitus tipo 2 (DM2), doenças cardiovasculares, hipertensão arterial, acidente vascular cerebral e até mesmo o câncer. Embora a obesidade esteja diretamente relacionada com o consumo calórico excessivo em relação ao gasto energético diário, sua etiologia pode estar associada aos baixos níveis de atividade física, às alterações neuroendócrinas e aos fatores genéticos. Considerando o componente genético, esta pode ser classificada como sindrômicas e estar associada às alterações cromossômicas estruturais ou numéricas, ou como não sindrômica, quando relacionada, principalmente, com os polimorfismos de nucleotídeos simples (SNPs) em alelos que atuam como herança monogênica, ou ainda com a interação vários genes (poligênica multifatorial). Apesar de existirem muitas etiologias diferentes, normalmente a obesidade é tratada a partir da mesma abordagem, desconsiderando a fisiologia que a desencadeou. Dessa forma, o objetivo do presente trabalho foi abordar a obesidade genética não sindrômica por meio a) da descrição breve de perspectiva histórica sobre seu entendimento; b) da exposição dos principais mecanismos moleculares envolvidos com o controle de peso; c) da compilação dos principais genes e SNPs relacionados; d) da definição dos principais genes; e e) da abordagem das principais perspectivas de intervenção.

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Obesity is defined as excess body fat accumulated in the adipose tissue when the individual reaches BMI values equal to or greater than 30 kg/m2. It is one of the main risk factors for several non-communicable diseases (NCDs), such as Type 2 Diabetes mellitus (T2D), cardiovascular diseases, high blood pressure, stroke and even cancer. Although obesity is directly related to excessive calorie intake in relation to daily energy expenditure, its etiology may be associated with low levels of physical activity, neuroendocrine changes, and genetic factors. Considering the genetic component, it can be classified as syndromic and be associated with chromosomal or numerical changes, or as non-syndromic and being related mainly to single nucleotide polymorphisms (SNPs) in alleles that act as monogenic inheritance, or with an interaction of several genes (multifactorial polygenic). Although there are many different etiologies, obesity is usually treated using the same approach, disregarding the physiology that triggered it. Thus, the aim of this study was to address non-syndromic genetic obesity through a) a brief description of a historical perspective on its understanding; b) the exposure of the main molecular mechanisms involved in weight control, c) the compilation of the key genes and related SNPs, d) the definition of the key genes and e) the approach of the main intervention representations.

Asunto(s)

Humanos , Masculino , Femenino , Peso Corporal/genética , Epigenómica , Genes/genética , Obesidad/genética , Índice de Masa Corporal , Expresión Génica/genética , Polimorfismo de Nucleótido Simple/genética , Receptor de Melanocortina Tipo 4/genética , Melanocortinas/genética , Receptores de Leptina/genética , Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato/genética , Hipotálamo/fisiopatología , Obesidad/fisiopatología

RESUMEN

INTRODUCTION: The melanocortin receptor 4 (MC4R) participates in the control of appetite at the level of the central nervous system, through the leptin-melanocortin pathway. An association between different polymorphisms of the MC4R gene and obesity has been reported. However, there are few studies of the rs483145 single nucleotide polymorphism (SNP) of this gene. OBJECTIVE: To investigate its prevalence and association with adiposity markers in Chilean adults. METHODS: The prevalence of SNP rs483145, of the MC4R gene, was determined in 259 participants of the GENADIO study (genes, environment, diabetes and obesity) by means of real-time polymerase chain reaction (PCR). The association between the risk allele of MC4R (A) and adiposity markers (body weight, body mass index, fat mass percentage, hip circumference, waist circumference, waist-to-hip ratio) was performed by linear regression analysis and adjusted for confusion variables (socio-demographic and physic activity) using three statistical models. RESULTS: It was determined that the prevalence of the risk allele (A) of the SNP rs483145 of the MC4R gene is 24.5% in the Chilean adult population included in this study, without finding an association with any of the adiposity markers studied, both in adjusted and unadjusted models. CONCLUSION: The presence of the risk allele of SNP rs483145 of the MC4R gene is not associated with adiposity markers in the Chilean adult population studied. New studies with a bigger sample size will be necessary to confirm these results.

Asunto(s)

Obesidad , Receptor de Melanocortina Tipo 4 , Adulto , Índice de Masa Corporal , Chile/epidemiología , Humanos , Obesidad/epidemiología , Obesidad/genética , Polimorfismo de Nucleótido Simple , Receptor de Melanocortina Tipo 4/genética

RESUMEN

Obesity and overweight are worldwide public health problems with an evident genetic predisposition that is still poorly understood. In addition, great variability has been described across populations. In this work, we analyzed the association of variants in four genes: PPARG (rs1801282), PPARGC1A (rs8192678), FTO (rs9939609) and MC4R (rs17782313) with overweight and obesity in a large sample of the Brazilian population. The case-control study involved 4084 individuals (1844 with overweight or obesity; and 2240 with normal BMI). Genotyping was performed by quantitative PCR. MC4R rs17782313-C was associated with obesity (OR = 1.27, p = 0.038) and when stratifying by sex associated only in women (OR = 1.36, p = 0.030). FTO rs9939609-A allele was associated with overweight however for women it represented a risk factor (OR = 1.24, p = 0.034) and for men, a protective factor (OR = 0.68, p = 0.033). PPARG was the strongest associated gene, with both overweight and obesity, and this association was also restricted to women (rs1801282-GG OR = 1.46, p = 0.027). The combined effect of the three risk alleles on overweight and obesity had an OR of 1.65 (p = 0.008) and when stratifying by sex again it was significant only in females (OR = 1.95, p = 0.0028). Our findings indicate that the three genes play a significant role in predisposing to overweight and/or obesity in the Brazilian population, reaching together a relatively high impact on these traits. Interestingly our results also suggest a strong sex-specific genetic effect of these variants.

Asunto(s)

Sobrepeso , PPAR gamma , Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato/genética , Índice de Masa Corporal , Estudios de Casos y Controles , Femenino , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Masculino , Obesidad/genética , Sobrepeso/genética , PPAR gamma/genética , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma , Polimorfismo de Nucleótido Simple , Receptor de Melanocortina Tipo 4/genética

RESUMEN

We investigated the association between the loss-of-function mutation MC4R p.Ile269Asn and T2D risk in the Mexican population. We enrolled 6929 adults [3175 T2D cases and 3754 normal glucose tolerant (NGT) controls] and 994 NGT children in the study. Anthropometric data and T2D-related quantitative traits were studied in 994 NGT children and 3754 NGT adults. The MC4R p.Ile269Asn mutation was genotyped using TaqMan. The MC4R p.Ile269Asn mutation was associated with T2D [OR = 2.00, 95% confidence interval (CI) 1.35-2.97, p = 0.00057] in Mexican adults. Additional adjustment for body-mass index (BMI) attenuated but did not remove the association (OR = 1.70, 95% CI 1.13-2.56, p = 0.011). The MC4R p.Ile269Asn mutation was associated with T2D (OR = 1.88, 95% CI 1.14-3.08, p = 0.013) in a subset of 1269 T2D cases and 1269 NGT controls matched for sex, age, and BMI. A mediation analysis estimated that BMI accounts for 22.7% of the association between MC4R p.Ile269Asn mutation and T2D risk (p = 4.55 × 10-6). An association was observed between the MC4R p.Ile269Asn mutation and BMI in NGT children and adults (children: beta = 3.731 ± 0.958, p = 0.0001; adults: beta = 2.269 ± 0.536, p = 2.3 × 10-5). In contrast, the mutation was not associated with T2D-related quantitative traits. We demonstrate that the MC4R p.Ile269Asn mutation predisposes to T2D via obesity-dependent and independent effects in the Mexican population.

Asunto(s)

Diabetes Mellitus Tipo 2/genética , Predisposición Genética a la Enfermedad , Obesidad/genética , Receptor de Melanocortina Tipo 4/genética , Adulto , Índice de Masa Corporal , Diabetes Mellitus Tipo 2/epidemiología , Diabetes Mellitus Tipo 2/patología , Femenino , Estudios de Asociación Genética , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Mutación/genética , Obesidad/epidemiología , Obesidad/patología , Fenotipo , Polimorfismo de Nucleótido Simple/genética , Factores de Riesgo

RESUMEN

CONTEXT: Studies in mice and humans suggest that melanocortin-4 receptor (MC4R) deficiency affects body weight in a sex-/gender-dependent manner. However, similar evidence for type 2 diabetes (T2D) is scarce. OBJECTIVE AND DESIGN: We investigated whether sex/gender modifies the association between the loss-of-function MC4R p.Ile269Asn mutation and T2D in 6929 Mexican adults (3175 T2D cases and 3754 normal glucose tolerance [NGT] controls). The 2003 American Diabetes Association criteria were used to define NGT and T2D. The MC4R p.Ile269Asn mutation was genotyped in all participants using TaqMan technology. RESULTS: The MC4R p.Ile269Asn mutation was associated with T2D in 6929 Mexican adults (Ncontrols = 3754, Ncases = 3175, odds ratio [OR] = 2.00, 95% confidence interval [CI], 1.35-2.97; P = 5.7 × 10-4). The MC4R p.Ile269Asn mutation had a frequency of 0.86 and 1.05% in women with NGT and T2D, and 0.78 and 1.32% in men with NGT and T2D, respectively. We identified a significant interaction between the MC4R p.Ile269Asn mutation and sex/gender on T2D risk (P = 0.049). Although a strong association between the mutation and T2D was observed in men (Ncontrols = 2418, Ncases = 1807, OR = 2.63, 95% CI, 1.62-4.28, P = 9.3 × 10-5), results were not significant in women (Ncontrols = 1336, Ncases = 1368, OR = 1.16, 95% CI, 0.60-2.26, P = 0.65). Further adjustment for body mass index in the logistic regression model did not alter the sex-/gender-specific pattern of association (men: OR = 2.22, 95% CI, 1.34-3.67, P = 0.0019; women: OR = 1.02, 95% CI, 0.51-2.02, P = 0.95). CONCLUSION: This is the first report of a male-specific association between the MC4R p.Ile269Asn loss-of-function mutation and T2D in the Mexican population.

Asunto(s)

Diabetes Mellitus Tipo 2/epidemiología , Diabetes Mellitus Tipo 2/genética , Receptor de Melanocortina Tipo 4/genética , Adulto , Anciano , Sustitución de Aminoácidos , Asparagina/genética , Estudios de Casos y Controles , Estudios Transversales , Modificador del Efecto Epidemiológico , Femenino , Frecuencia de los Genes , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Isoleucina/genética , Masculino , México/epidemiología , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Factores de Riesgo , Factores Sexuales

RESUMEN

PURPOSE: The rs17782313 variant of the MC4R gene plays an important role in the obesity phenotype. Studies that evaluate environmental factors and genetic variants associated with obesity may represent a great advance in understanding the development of this disease. This work seeks to assess the association of the polymorphism of MC4R rs17782313 on plasma parameters, including leptin, ghrelin, tumor necrosis factor (TNFα) and interleukin 6 (IL6), and on the eating behaviors of morbidly obese women. METHODS: 70 adult women with BMI between 40 and 60 kg/m2 were recruited. Laboratory and anthropometric data were recorded. Using a visual analog scale (VAS), the feelings of hunger and satiety were evaluated. The presence or absence of binge eating was evaluated through the Binge Eating Scale (BES) questionnaire. Habitual food intake was analyzed using 3-day dietary records. TaqMan® assays were conducted using real-time PCR to assess genotype polymorphism variants from peripheral blood DNA. RESULTS: This study found that female patients with the MC4R rs17782313 polymorphism had high levels of ghrelin and reduced levels of IL6 in the postprandial period. We observed a higher prevalence of severe binge eating in more than 50% of women with at least one risk allele. CONCLUSION: Our hypothesis is that the MC4R rs17782313 polymorphism may influence the release of ghrelin, even without being associated with feelings of hunger and satiety. More than half of women with this polymorphism exhibited severe binge eating. LEVEL OF EVIDENCE: Level III: case-control analytic study.

Asunto(s)

Leptina , Obesidad Mórbida , Adulto , Índice de Masa Corporal , Ingestión de Alimentos/genética , Conducta Alimentaria , Femenino , Ghrelina/genética , Humanos , Interleucina-6/genética , Leptina/genética , Obesidad Mórbida/genética , Polimorfismo de Nucleótido Simple , Receptor de Melanocortina Tipo 4/genética , Factor de Necrosis Tumoral alfa

RESUMEN

PURPOSE: Monogenic forms of obesity are caused by single-gene variants which affect the energy homeostasis by increasing food intake and decreasing energy expenditure. Most of these variants result from disruption of the leptin-melanocortin signaling, which can cause severe early-onset obesity and hyperphagia. These mutation have been identified in genes encoding essential proteins to this pathway, including leptin (LEP), melanocortin 2 receptor accessory proteins 2 (MRAP2) and proopiomelanocortin (POMC). We aimed to investigate the prevalence of LEP, MRAP2 and POMC rare variants in severely obese adults, who developed obesity during childhood. To the best of our knowledge, this is the first study screening rare variants of these genes in patients from Brazil. METHODS: A total of 122 Brazilian severely obese patients (BMI ≥ 35 kg/m2) were screened for the coding regions of LEP, MRAP2 and POMC by Sanger sequencing. All patients are candidates to the bariatric surgery. Clinical characteristics were described in patients with novel and/or potentially pathogenic variants. RESULTS: Sixteen different variants were identified in these genes, of which two were novel. Among them, one previous variant with potentially deleterious effect in MRAP2 (p.Arg125Cys) was found. In addition, two heterozygous mutations in POMC (p.Phe87Leu and p.Arg90Leu) were predicted to impair protein function. We also observed a POMC homozygous 9 bp insertion (p.Gly99_Ala100insSerSerGly) in three patients. No pathogenic variant was observed in LEP. CONCLUSION: Our study described for the first time the prevalence of rare potentially pathogenic MRAP2 and POMC variants in a cohort of Brazilian severely obese adults. LEVEL OF EVIDENCE: Level V, cross-sectional descriptive study.

Asunto(s)

Obesidad Mórbida , Proopiomelanocortina , Proteínas Adaptadoras Transductoras de Señales , Adulto , Brasil , Estudios Transversales , Humanos , Leptina , Obesidad Mórbida/genética , Proopiomelanocortina/genética , Proproteína Convertasas , Receptor de Melanocortina Tipo 4/genética

RESUMEN

OBJECTIVE: The melanocortin 4 receptor (MC4R) is a G protein-coupled receptor that plays major roles in the central control of energy balance. Loss-of-function mutations of MC4R constitute the most common monogenic cause of early-onset extreme obesity in humans, whereas gain-of-function mutations appear to be protective. In particular, two relatively frequent alleles carrying the non-synonymous coding mutations V103I or I251L are associated with lower risks of obesity and type-2 diabetes. Although V103I and I251L MC4Rs showed more efficient signalling in transfected cells, their specific effects in live animals remain unexplored. Here, we investigated whether the introduction of V103I and I251L mutations into the mouse MC4R leads to a lean phenotype and provides protection against an obesogenic diet. METHODS: Using CRISPR/Cas9, we generated two novel strains of mice carrying single-nucleotide mutations into the mouse Mc4r which are identical to those present in V103I and I251L MCR4 human alleles, and studied their phenotypic outcomes in mice fed with normal chow or a high-fat diet. In particular, we measured body weight progression, food intake and adiposity. In addition, we analysed glucose homeostasis through glucose and insulin tolerance tests. RESULTS: We found that homozygous V103I females displayed shorter longitudinal length and decreased abdominal white fat, whereas homozygous I251L females were also shorter and leaner due to decreased weight in all white fat pads examined. Homozygous Mc4rV103I/V103I and Mc4rI251L/I251L mice of both sexes showed improved glucose homeostasis when challenged in a glucose tolerance test, whereas Mc4rI251L/I251L females showed improved responses to insulin. Despite being leaner and metabolically more efficient, V103I and I251L mutants fed with a hypercaloric diet increased their fasting glucose levels and adiposity similar to their wild-type littermates. CONCLUSIONS: Our results demonstrate that mice carrying V103I and I251L MC4R mutations displayed gain-of-function phenotypes that were more evident in females. However, hypermorphic MC4R mutants were as susceptible as their control littermates to the obesogenic and diabetogenic effects elicited by a long-term hypercaloric diet, highlighting the importance of healthy feeding habits even under favourable genetic conditions.

Asunto(s)

Adiposidad/genética , Receptor de Melanocortina Tipo 4/metabolismo , Aumento de Peso/genética , Adiposidad/fisiología , Animales , Dieta Alta en Grasa , Metabolismo Energético , Femenino , Mutación con Ganancia de Función/genética , Glucosa/metabolismo , Homeostasis/genética , Humanos , Insulina/metabolismo , Masculino , Ratones , Ratones Transgénicos , Obesidad/genética , Receptor de Melanocortina Tipo 4/genética

RESUMEN

Introduction: Obesity is considered a serious public health problem. Efforts have been directed to search for candidate genes such as LEP, LEPR, and MC4R involved in the leptin-melanocortin system. The neuroendocrine regulation of these genes on energy intake and balance influences the pathogenesis of this disease. Contradictory results regarding the association of these genes with obesity raise the need for new research. Objective: To analyze the association between obesity and LEP rs2167270, LEPR rs1137101, and MC4R rs17782313 polymorphisms and the clinical and biochemical variables in obese adults from Barranquilla, Colombia. Materials and methods: We analyzed 111 obese adults and 155 non-obese individuals as controls. The polymorphisms were determined by real-time PCR. Besides, anthropometric measures, blood pressure, and biochemical tests were evaluated. Results: No statistical differences were found in allele and genotype frequencies of gene polymorphisms between groups. The CC genotype of MC4R rs17782313 polymorphism was associated with increased systolic blood pressure and T allele and TT genotype, with decreased HDL cholesterol in obese adults. The effect of the other polymorphisms on these variables was not evidenced. Conclusions: LEP rs2167270, LEPR rs1137101, and MC4R rs17782313 polymorphisms were not associated with obesity in the population under study. MC4R rs17782313 polymorphisms were associated with an increase in systolic blood pressure and a decrease in HDL cholesterol.

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Introducción. La obesidad se considera un grave problema de salud pública y por ello se hacen esfuerzos en la búsqueda de genes como el LEP, el LEPR y el MC4R del sistema leptina-melanocortina, el cual opera en la regulación neuroendocrina de la ingestión y el equilibrio energético e influye en la patogenia de la enfermedad. Los resultados contradictorios en torno a la asociación de estos genes con la obesidad plantean la necesidad de nuevas investigaciones. Objetivo. Analizar los polimorfismos rs2167270 del gen LEP, rs1137101 del gen LEPR y rs17782313 del gen MC4R asociados con la obesidad y sus variables clínicas y bioquímicas en una muestra de pacientes adultos de Barranquilla. Materiales y métodos. Se estudiaron 111 personas obesas y 155 no obesas como controles. Los polimorfismos se determinaron mediante reacción en cadena de la polimerasa (PCR) en tiempo real. Se tomaron las medidas antropométricas, se evaluó la presión arterial y se hicieron pruebas bioquímicas. Resultados. No se encontraron diferencias estadísticas en la frecuencia alélica y genotípica de los polimorfismos en los grupos estudiados. En cuanto a las variables clínicas y bioquímicas, el genotipo CC del polimorfismo rs17782313 del gen MC4R, se asoció con un aumento de la presión arterial sistólica y, el alelo T y su genotipo homocigoto, con una disminución del colesterol HDL en los obesos. No se evidenció ningún efecto de los otros polimorfismos en estas variables. Conclusiones. Los polimorfismos rs2167270 del gen LEP, rs1137101 del gen LEPR y rs17782313 del gen MC4R, no se asociaron con obesidad en la población analizada. Se encontró que el polimorfismo rs17782313 del gen MC4R influyó en el aumento de la presión arterial sistólica y la disminución del colesterol HDL en las personas obesas.

Asunto(s)

Leptina/genética , Obesidad/genética , Polimorfismo de Nucleótido Simple , Receptor de Melanocortina Tipo 4/genética , Receptores de Leptina/genética , Adulto , Anciano , Alelos , Presión Sanguínea/genética , Estudios de Casos y Controles , HDL-Colesterol/sangre , Colombia/epidemiología , Estudios Transversales , Femenino , Frecuencia de los Genes , Genotipo , Hemoglobina Glucada/análisis , Humanos , Insulina/sangre , Masculino , Persona de Mediana Edad , Obesidad/sangre , Obesidad/epidemiología , Reacción en Cadena en Tiempo Real de la Polimerasa , Muestreo , Adulto Joven

RESUMEN

BACKGROUND: Mexico is experiencing an epidemic of childhood obesity and overweight, the factors that determine type 2 diabetes and cardiovascular diseases. Even though variants in genes such as MC4R, LEP, LEPR, and FTO have been associated with the risk of obesity, in Mexico the level of miscegenation is heterogeneous, so this risk must be measured as genetic ancestry. This study aimed at evaluating the association between common SNPs in FTO and MC4R genes in Mexican children with Amerindian, mestizo and predominance European ancestry. METHODS: Anthropometric data and fasting blood samples were collected from 718 unrelated Mexican school children aged 4-13 years old. Variants in the FTO, MC4R, LEP, LEPR genes and 15 ancestry informative markers (AIMs), were genotyped using allelic discrimination assays. RESULTS: High triglycerides and low cholesterol HDL were the most frequent metabolic alterations. The prevalence of minor allele frequency of polymorphism rs8050136, rs9939609, and rs3751812 in the FTO gene; and rs17782313 of MC4R gene were found to be significantly higher among Mexican children with a predominance of European ancestry (EA) compared to native Mexican children (Amerindian predominance), X2 test, p < 0.05. The FTO (rs8050136, rs9939609) and MC4R (rs17782313) genotypes also were significantly associated with obesity (BMI > 2Z) in boys (OR=1.89, P=0.04, OR=3.3, P=0.006 OR=3.11, p=0.04, respectively). Children with AA genotype (minor) of rs8050136 and rs9939609 SNPs have higher triglycerides in relation to native ancestral genotypes. CONCLUSION: Risk variants in the FTO and MC4R genes had a higher frequency in children with EA compared with Amerindian predominance children, showing that miscegenation is associated with the frequency of obesity-related genotypes.

Asunto(s)

Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato/genética , Biomarcadores/metabolismo , Índice de Masa Corporal , Etnicidad/genética , Predisposición Genética a la Enfermedad , Obesidad Infantil/epidemiología , Polimorfismo de Nucleótido Simple , Receptor de Melanocortina Tipo 4/genética , Adolescente , Niño , Preescolar , Femenino , Genotipo , Humanos , Masculino , México/epidemiología , Sobrepeso/epidemiología , Sobrepeso/genética , Sobrepeso/metabolismo , Obesidad Infantil/genética , Obesidad Infantil/metabolismo , Prevalencia

RESUMEN

Excessive alcohol intake affects hippocampal function and neuronal communication through oxidative stress and mitochondrial impairment. Previous studies have suggested that the melanocortin system (MCS) plays an essential role in alcohol consumption and addiction. The MCS is a hypothalamic region involved in regulating inflammatory processes in the brain, and its pharmacological activation through the melanocortin-4 receptor (MC4R) reduces both alcohol consumption and the neuroinflammatory responses in the brain. However, the cellular mechanisms involved in the beneficial actions of MCS against ethanol toxicity are not entirely understood. The objective of this study was to investigate the protective role of the MC4R pharmacological activator RO27-3225 on oxidative damage and mitochondrial impairment present in hippocampal neuronal cultures acutely exposed to ethanol (50, 75 mM, 24 h). Pre-treatment with RO27-3225 (250 nM, 1 h) prevented reactive oxygen species (ROS) increase, dysregulation of cytosolic calcium homeostasis, and mitochondrial potential loss induced by ethanol. Improvement of mitochondrial failure produced by RO27-3225 was accompanied by a significant increase in ATP production in ethanol-treated neurons. More importantly, RO27-3225 promoted the activation of the antioxidant pathway Nrf-2, demonstrated by an increase in the expression and nuclear translocation of Nrf-2, and upregulation of mRNA levels of NAD(P)H quinone oxidoreductase 1 (NQO1), an antioxidant enzyme which expression is activated by this pathway. These results suggest that the stimulation of MC4R prevents oxidative damage and mitochondrial stress induced by ethanol through the activation of the Nrf-2 pathway in cultured hippocampal neurons. These results are novel and demonstrate the critical function of MC4R in promoting antioxidant defense and reducing mitochondrial damage produced by ethanol in the brain.

Asunto(s)

Calcio/metabolismo , Potencial de la Membrana Mitocondrial/fisiología , Mitocondrias/metabolismo , Neuronas/metabolismo , Fármacos Neuroprotectores/farmacología , Estrés Oxidativo/fisiología , Péptidos/farmacología , Receptor de Melanocortina Tipo 4/metabolismo , Animales , Antioxidantes , Células Cultivadas , Depresores del Sistema Nervioso Central/toxicidad , Etanol/toxicidad , Hipocampo/citología , Inflamación/metabolismo , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Mitocondrias/efectos de los fármacos , NAD(P)H Deshidrogenasa (Quinona)/efectos de los fármacos , NAD(P)H Deshidrogenasa (Quinona)/genética , Factor 2 Relacionado con NF-E2/efectos de los fármacos , Factor 2 Relacionado con NF-E2/metabolismo , Neuronas/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , ARN Mensajero/efectos de los fármacos , ARN Mensajero/metabolismo , Ratas , Especies Reactivas de Oxígeno/metabolismo , Receptor de Melanocortina Tipo 4/agonistas

RESUMEN

CONTEXT: Rare partial/complete loss-of-function mutations in the melanocortin-4 receptor (MC4R) gene are the most common cause of Mendelian obesity in European populations, but their contribution to obesity in the Mexican population is unclear. OBJECTIVE AND DESIGN: We investigated whether deleterious mutations in MC4R contribute to obesity in Mexican children and adults. RESULTS: We provide evidence that the MC4R p.Ile269Asn (rs79783591) mutation may have arisen in modern human populations from a founder event in native Mexicans. The MC4R Isoleucine 269 is perfectly conserved across 184 species, which suggests a critical role for the amino acid in MC4R activity. Four in silico tools (SIFT, PolyPhen-2, CADD, MutPred2) predicted a deleterious impact of the p.Ile269Asn substitution on MC4R function. The MC4R p.Ile269Asn mutation was associated with childhood (Ncontrols = 952, Ncases = 661, odds ratio (OR) = 3.06, 95% confidence interval (95%CI) [1.94-4.85]) and adult obesity (Ncontrols = 1445, Ncases = 2,487, OR = 2.58, 95%CI [1.52-4.39]). The frequency of the MC4R p.Ile269Asn mutation ranged from 0.52 to 0.59% and 1.53 to 1.59% in children and adults with normal weight and obesity, respectively. The MC4R p.Ile269Asn mutation co-segregated perfectly with obesity in 5 multigenerational Mexican pedigrees. While adults with obesity carrying the p.Ile269Asn mutation had higher BMI values than noncarriers, this trend was not observed in children. The MC4R p.Ile269Asn mutation accounted for a population attributable risk of 1.28% and 0.68% for childhood and adult obesity, respectively, in the Mexican population. CONCLUSION: The MC4R p.Ile269Asn mutation may have emerged as a founder mutation in native Mexicans and is associated with childhood and adult obesity in the modern Mexican population.

Asunto(s)

Biomarcadores/análisis , Predisposición Genética a la Enfermedad , Mutación , Obesidad/epidemiología , Obesidad/genética , Receptor de Melanocortina Tipo 4/genética , Adulto , Índice de Masa Corporal , Niño , Femenino , Estudios de Seguimiento , Genotipo , Humanos , Masculino , México/epidemiología , Persona de Mediana Edad , Obesidad/patología , Linaje , Fenotipo , Pronóstico

RESUMEN

BACKGROUND: High ethanol intake induces a neuroinflammatory response resulting in the subsequent maintenance of chronic alcohol consumption. The melanocortin system plays a pivotal role in the modulation of alcohol consumption. Interestingly, it has been shown that the activation of melanocortin-4 receptor (MC4R) in the brain decreases the neuroinflammatory response in models of brain damage other than alcohol consumption, such as LPS-induced neuroinflammation, cerebral ischemia, glutamate excitotoxicity, and spinal cord injury. OBJECTIVES: In this work, we aimed to study whether MC4R activation by a synthetic MC4R-agonist peptide prevents ethanol-induced neuroinflammation, and if alcohol consumption produces changes in MC4R expression in the hippocampus and hypothalamus. METHODS: Ethanol-preferring Sprague Dawley rats were selected offering access to 20% ethanol on alternate days for 4 weeks (intermittent access protocol). After this time, animals were i.p. administered an MC4R agonist peptide in the last 2 days of the protocol. Then, the expression of the proinflammatory cytokines interleukin 6 (IL-6), interleukin 1-beta (IL-1ß), and tumor necrosis factor-alpha (TNF-α) were measured in the hippocampus, hypothalamus and prefrontal cortex. It was also evaluated if ethanol intake produces alterations in the expression of MC4R in the hippocampus and the hypothalamus. RESULTS: Alcohol consumption increased the expression of MC4R in the hippocampus and the hypothalamus. The administration of the MC4R agonist reduced IL-6, IL-1ß and TNF-α levels in hippocampus, hypothalamus and prefrontal cortex, to those observed in control rats that did not drink alcohol. CONCLUSION: High ethanol consumption produces an increase in the expression of MC4R in the hippocampus and hypothalamus. The administration of a synthetic MC4R-agonist peptide prevents neuroinflammation induced by alcohol consumption in the hippocampus, hypothalamus, and prefrontal cortex. These results could explain the effect of α-MSH and other synthetic MC4R agonists in decreasing alcohol intake through the reduction of the ethanol-induced inflammatory response in the brain.

Asunto(s)

Inflamación/prevención & control , Receptor de Melanocortina Tipo 4/agonistas , alfa-MSH , Animales , Etanol/efectos adversos , Hipocampo/efectos de los fármacos , Hipotálamo/efectos de los fármacos , Inflamación/inducido químicamente , Corteza Prefrontal/efectos de los fármacos , Ratas , Ratas Sprague-Dawley