RESUMEN
Central obesity and body fat distribution measured by waist circumference (WC) and waist hip ratio (WHR) are good predictors of cardio metabolic adversities independent of overall adiposity. There are substantial evidence that body fat distribution is controlled by genetic factors. Even after accounting for body mass index (BMI), individual variation in body fat distribution is heritable, with estimates ranging from 31-76%. Individuals genetically predisposed to store more fat in visceral depots are at higher risk of developing metabolic complications. Several linkage and genomewide association studies (GWAS) for measures of body fat distribution uncovered numerous loci harbouring genes potentially regulating body fat distribution. Additionally, genes with fat depot specific expression patterns (especially, subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT)) have provided plausible candidate genes involved in body fat regulation. Further, sexual dimorphism have revealed a remarkable heterogeneity in the genetic regulation of body fat distribution. More than hundred loci have been identified through GWAS, displaying more pronounced effect in females than males, suggesting that both sexes share potentially different biological architecture in traits related to body fat distribution. Moreover, the handful of genes identified by GWAS have been validated in different population groups. This article aims at reviewing the current knowledge of genomic basis of body fat distribution.
Asunto(s)
Composición Corporal/genética , Distribución de la Grasa Corporal , Predisposición Genética a la Enfermedad , Obesidad/genética , Índice de Masa Corporal , Femenino , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Obesidad/patología , Caracteres SexualesRESUMEN
BACKGROUND AND AIMS: The association of melanocortin receptor 4 (MC4R) gene with adiposity measures is widely studied in European populations. Only six studies have investigated the role of MC4R gene with adiposity measures among Indian populations. We have evaluated the role of MC4R (rs17782313) gene polymorphism in influencing adiposity measures in India among children and adults. MATERIALS AND METHODS: The present population based cross sectional study was conducted among 303 individuals (208 children and 95 adults) of age group 10-30 years, belonging to Rajasthan. Somatometric measurements (standing height, weight, and waist and hip girths) and blood samples were taken after obtaining written informed consent. Genotyping of MC4R rs17782313 single nucleotide polymorphism was done using restriction fragment length polymorphism method for polymerase chain reaction ampliï¬ed fragments. We examined association between rs17782313 and different adiposity measures (height, weight, BMI, WHR, and waist and hip girths) using linear regression models. RESULTS: The MC4R variant (rs17782313) predicted increased body weight (0.15 kg, S.E ± 0.076, P = 0.043) among children. In combined population, the rs17782313 variant was moderately associated with body weight (0.13 kg, S.E ± 0.070, P = 0.057). This variant was not found to be associated with any other adiposity measure. CONCLUSION: Further studies are needed to evaluate the association of MC4R variants through sequencing and functional genomics with different adiposity measures in Indian populations for understanding the genetic underpinnings of adiposity in India.
Asunto(s)
Índice de Masa Corporal , Peso Corporal , Predisposición Genética a la Enfermedad , Obesidad/epidemiología , Polimorfismo de Nucleótido Simple , Receptor de Melanocortina Tipo 4/genética , Circunferencia de la Cintura , Adolescente , Adulto , Niño , Estudios Transversales , Femenino , Estudios de Seguimiento , Humanos , India/epidemiología , Masculino , Obesidad/genética , Obesidad/patología , Pronóstico , Adulto JovenRESUMEN
Obesity is one of the largest global health problems associated with increased morbidity and mortality mediated by its association with several other metabolic disorders. The interaction between the genes and environment plays an important role in the manifestation of obesity. Despite a high heritability (40-70%) of obesity, the search for genetic variants associated with obesity susceptibility has been a challenging task. To date, limited studies have been conducted in India, restricted to the validation of few genetic variants identified by genomewide association studies. In this critical review, we sought to examine the current knowledge of genetic basis of obesity and its measures in the Indian population. A comprehensive literature search was performed using 'PubMed', 'Medline' and 'IndMed' databases to search for citations published until 31st May 2017, using the key terms as 'Genetics' AND 'obesity' AND 'India'. We identified 48 potential studies which fulfilled the eligibility criteria. The findings indicated that FTO, MC4R, TNF-α, PPAR-γ , UCP1, UCP2, LPL, LEPR, AMD1, IL6, APOE, ADIPOQ, DOK5, INSIG2, PBEF1, IL6R, Myostatin, CXCR4, HHEX, IRX3, POMC, NGN3, FOXA2, MTR, TCN and CHDH are some of the important genes studied among the Indian population. Importantly, the role of sexual dimorphism in the genetic regulation of obesity and body fat distribution was also reported in a few studies. Further, seven biological pathways have been identified that contribute to obesity pathogenesis in India. In conclusion, further exploration of pathway-based research on genetics of obesity can be useful for better understanding the pathophysiology of obesity in India.