RESUMO
Prader-Willi (PWS) and Angelman (AS) syndromes are two clinically distinct imprinted disorders characterized by genetic abnormalities at 15q11-q13. Early diagnosis of both syndromes provides improved treatment and accurate genetic counseling. Whole blood (WB) is the most common DNA source of many methodologies to detect PWS and AS, however, the need of WB makes a massive screening difficult in newborns due to economic and technical limitations. The aim of this study was to adapt a Methylation-sensitive High-Resolution Melting (MS-HRM) approach from dried blood spot (DBS) samples, assessing the different DNA isolation techniques and diagnostic performance. Over a 1-year period, we collected 125 DBS cards, of which 45 had already been diagnosed by MS-HRM (20 PWS, 1 AS, and 24 healthy individuals). We tested three different DBS-DNA extraction techniques assessing the DNA concentration and quality, followed by MS-HRM and statistical comparison. Each DBS-DNA extraction method was capable of accuracy in detecting all PWS and AS individuals. However, the efficiency to detect healthy individuals varied according to methodology. In our experience, DNA extracted from DBS analyzed by the MS-HRM methodology provides an accurate approach for genetic screening of imprinting related disorders in newborns, offering several benefits compared to traditional whole blood methods.
Assuntos
Síndrome de Angelman/sangue , Síndrome de Angelman/genética , Metilação de DNA/genética , Teste em Amostras de Sangue Seco , Triagem Neonatal , Desnaturação de Ácido Nucleico/genética , Síndrome de Prader-Willi/sangue , Síndrome de Prader-Willi/genética , Autoantígenos/genética , Humanos , Recém-Nascido , Projetos Piloto , Ribonuclease P/genéticaRESUMO
BACKGROUND: Prader Willi (PWS) and Angelman (AS) syndromes are rare genetic disorders characterized by deletions, uniparental disomy, and imprinting defects at chromosome 15. The loss of function of specific genes caused by genetic alterations in paternal allele causes PWS while the absence in maternal allele results AS. The laboratory diagnosis of PWS and AS is complex and demands molecular biology and cytogenetics techniques to identify the genetic mechanism related to the development of the disease. The DNA methylation analysis in chromosome 15 at the SNURF-SNRPN locus through MS-PCR confirms the diagnosis and distinguishes between PWS and AS. Our study aimed to establish the MS-PCR technique associated with High-Resolution Melting (MS-HRM) in PWS and AS diagnostic with a single pair of primers. METHODS: We collected blood samples from 43 suspected patients to a cytogenetic and methylation analysis. The extracted DNA was treated with bisulfite to perform comparative methylation analysis. RESULTS: MS-HRM and MS-PCR agreed in 100% of cases, identifying 19(44%) PWS, 3(7%) AS, and 21(49%) Normal. FISH analysis detected four cases of PWS caused by deletions in chromosome 15. CONCLUSION: The MS-HRM showed good performance with a unique pair of primers, dispensing electrophoresis gel analysis, offering a quick and reproducible diagnostic.
Assuntos
Síndrome de Angelman/diagnóstico , Reação em Cadeia da Polimerase/métodos , Síndrome de Prader-Willi/diagnóstico , Síndrome de Angelman/sangue , Síndrome de Angelman/genética , Cromossomos Humanos Par 15/genética , Metilação de DNA/genética , Primers do DNA/genética , Epigênese Genética/genética , Feminino , Humanos , Masculino , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Síndrome de Prader-Willi/sangue , Síndrome de Prader-Willi/genética , Proteínas Centrais de snRNP/genética , Proteínas Centrais de snRNP/metabolismoRESUMO
OBJECTIVES: To describe the response of thyroid-stimulating hormone (TSH) to thyroid-releasing hormone in children and adolescents with Prader-Willi syndrome (PWS), and to compare TSH and total thyroxine (TT4) concentrations measured on neonatal screening for congenital hypothyroidism in children with PWS and controls. STUDY DESIGN: All participants had genetically confirmed PWS. The TSH responses to thyroid-releasing hormone, free thyroxine (fT4), and free triiodothyronine (fT3) were measured in 21 subjects (14 females and 7 males; mean age, 6.4 years). Capillary TT4 was measured on neonatal screening samples from 23 subjects with PWS (14 females and 9 males), each of whom was matched for birth weight and sex with 4 anonymized controls. RESULTS: One subject with PWS had tertiary hypothyroidism. TSH level increased from 1.37 mU/L at baseline to 39.6 mU/L at 20 minutes, 47.2 mU/L at 40 minutes, 44.5 mU/L at 60 minutes, and 47.2 mU/L at 120 minutes. fT4 concentration was 6.3 pmol/L, and fT3 concentration was 4.6 pmol/L. In the other 20 subjects, mean TSH level was 1.9 mU/L (range, 0.8-4.2 mU/L) at baseline and 21.8 mU/L (range, 10.0-46.7 mU/L) at 20 minutes (peak). Mean fT4 concentration (10.4 pmol/L; range, 8.2-13.5 pmol/L) was in the lower one-third of the normal range in 18 subjects, and mean fT3 concentration (6.1 pmol/L; range, 4.8-8.4 pmol/L) was above the median in 13 subjects. In neonates, mean TSH level was 3.1 mU/L (range, 0.4-10.0 mU/L) in subjects with PWS versus 3.3 mU/L (range, 0.0-7.0 mU/L) in controls, and mean TT4 in subjects with PWS was 111% (range, 17%-203%) that of controls (P = not significant). CONCLUSION: Thyroid function was normal in our newborn subjects. In older children, frank hypothyroidism was found in only 1 of our 21 subjects. Thus, levothyroxine treatment should not be routinely prescribed to youth with PWS.
Assuntos
Hipotireoidismo/etiologia , Síndrome de Prader-Willi/complicações , Tireotropina/sangue , Tiroxina/sangue , Tri-Iodotironina/sangue , Adolescente , Biomarcadores/sangue , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Humanos , Hipotireoidismo/sangue , Hipotireoidismo/diagnóstico , Lactente , Recém-Nascido , Masculino , Triagem Neonatal , Síndrome de Prader-Willi/sangue , Síndrome de Prader-Willi/diagnósticoRESUMO
Prader-Willi syndrome (PWS) is a genetic disorder characterized by dysmorphic features, obesity, hypogonadism, hypotonia and mental retardation. Obesity has been linked to insulin resistance and the latter has also been associated with premature adrenarche. Since up to date a controlled study to investigate adrenarche and its hormonal regulation was lacking in PWS, our aim was to assess whether prepubertal PWS patients develop premature adrenarche and its relationship with markers of insulin sensitivity. Fourteen prepubertal children with PWS (6 M, 8 F) and 10 non-syndromal simple obese matched controls (5 M, 5 F) participated (mean age: 7.62 +/- 1.84 years). A fasting blood sample was obtained for adrenal and ovarian androgens, sex hormone binding globulin, insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein-1, leptin, adiponectin and a lipid profile. Thereafter an oral glucose tolerance test was performed. PWS patients were smaller at birth and a higher proportion displayed premature pubarche. No differences were found in testosterone, androstenedione, sex hormone binding globulin, free androgen index, homeostatic model assessment-IR, 2-hour insulin, leptin or adiponectin levels. 17-hydroxyprogesterone and DHEAS levels however, were significantly higher in PWS. IGF-I levels were significantly lower in PWS and correlated significantly with height SDS (p < 0.05). In conclusion, a higher proportion of premature adrenarche in our PW patients was observed, which was not explained by differences in insulin sensitivity or plasma levels of adipokines and IGF-I.
Assuntos
Adrenarca/sangue , Resistência à Insulina , Síndrome de Prader-Willi/sangue , Síndrome de Prader-Willi/fisiopatologia , Adiponectina/sangue , Adrenarca/metabolismo , Estudos de Casos e Controles , Criança , Feminino , Glucose/metabolismo , Humanos , Metabolismo dos Lipídeos , Masculino , Síndrome de Prader-Willi/metabolismo , Puberdade/sangueRESUMO
OBJECTIVE: To explore the hypothesis that high ghrelin levels contribute to obesity in Prader-Willi syndrome (PWS), we assessed whether the increased levels observed in older persons with PWS exist in very young children, before the onset of hyperphagia. STUDY DESIGN: We measured ghrelin levels in nine children with PWS (17-60 months of age) and eight healthy control subjects of equivalent body mass index (BMI), age, and sex. RESULTS: PWS and control groups had equivalent BMI (16.8 +/- 1.4 vs 16.1 +/- 0.9 kg/m(2), respectively; P = .24), age (37.8 +/- 15.4 vs 50.3 +/- 17.7 months; P = .14), and sex. PWS and control groups also had equivalent fasting levels of total ghrelin (787 +/- 242 vs 716 +/- 135 pg/mL, respectively; P = .24), bioactive ghrelin (102 +/- 35 vs 91 +/- 23 pg/mL; P = .45), insulin, and glucose. Ghrelin correlated negatively with BMI among controls (r = -0.760, P = .029) but not PWS (r = 0.015, P = .97). CONCLUSIONS: Children <5 years of age with PWS, who had not yet developed hyperphagia or excessive obesity, had normal ghrelin levels, in contrast with the hyperghrelinemia of older, hyperphagic people with PWS. It is possible that ghrelin levels increase suddenly before hyperphagia develops.
Assuntos
Hormônios Peptídicos/sangue , Síndrome de Prader-Willi/sangue , Índice de Massa Corporal , Pré-Escolar , Cromatografia Líquida de Alta Pressão , Feminino , Grelina , Humanos , Masculino , RadioimunoensaioRESUMO
Prader-Willi Syndrome (PWS) is a genetic disorder characterized by hypotonia, mental retardation or learning disability, hyperphagia and compulsive eating due to hypothalamic dysfunction. Obesity is a major cause of increased morbidity and mortality among patients with PWS. Gastric restrictive surgery has been associated with partial breakdown of the staple-line in PWS. We report two patients with PWS associated with morbid obesity and obstructive sleep apnea who underwent biliopancreatic diversion (BPD). A 27-year-old male with BMI 52 kg/m(2) and a 20 year-old female with BMI 64 kg/m(2) underwent BPD. No perioperative complications were observed. After BPD, the male's BMI was 36.7 kg/m(2) at 12 months and the female's BMI was 48.4 kg/m(2) at 28 months, with excess weight loss 58% and 48%, respectively. They developed loose stools associated with eating. These patients have shown a considerable improvement in hypersomnia and respiratory difficulties. BPD proved to be an effective approach to weight loss in PWS, resulting in improvement of sleep apnea, behavior problems and quality of life.