RESUMEN
Context: The population of Guadeloupe Island exhibits a high prevalence of obesity. Objective: We aimed to investigate whether rare genetic mutations in genes involved in monogenic obesity (or diabetes) might be causal in this population of Afro-Caribbean ancestry. Design and Setting: This was a secondary analysis of a study on obesity conducted in schoolchildren from Guadeloupe in 2013 that aimed to assess changes in children's profiles after a lifestyle intervention program. Through next-generation sequencing, we sequenced coding regions of 59 genes involved in monogenic obesity or diabetes in participants from this study. Participants and Interventions: A total of 25 obese schoolchildren from Guadeloupe were screened for rare mutations (nonsynonymous, splice-site, or insertion/deletion) in 59 genes. Main Outcome Measures: Correlation between phenotypes and mutations of interest. Results: We detected five rare heterozygous mutations in five different children with obesity: MC4R p.Ile301Thr and SIM1 p.Val326Thrfs*43 mutations that were pathogenic; SIM1 p.Ser343Pro and SH2B1 p.Pro90His mutations that were likely pathogenic; and NTRK2 p.Leu140Phe that was of uncertain significance. In parallel, we identified seven carriers of mutations in ABCC8 (p.Lys1521Asn and p.Ala625Val) or KCNJ11 (p.Val13Met and p.Val151Met) that were of uncertain significance. Conclusions: We were able to detect pathogenic or likely pathogenic mutations linked to severe obesity in >15% of this population, which is much higher than what we observed in Europeans (â¼5%).
Asunto(s)
Población Negra , Obesidad Infantil/epidemiología , Obesidad Infantil/genética , Adolescente , Población Negra/genética , Población Negra/estadística & datos numéricos , Región del Caribe/etnología , Niño , Estudios de Cohortes , Análisis Mutacional de ADN , Femenino , Guadalupe/epidemiología , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Masculino , Mutación , Obesidad Infantil/etnología , Prevalencia , Instituciones Académicas/estadística & datos numéricos , Estudiantes/estadística & datos numéricosRESUMEN
Introduction. Increase in body weight is a gradual process that usually begins in childhood and in adolescence as a result of multiple interactions among environmental and genetic factors. This study aimed to analyze the relationship between copy number variants (CNVs) in five genes and four intergenic regions with obesity in Mexican children. Methods. We studied 1423 children aged 6-12 years. Anthropometric measurements and blood levels of biochemical parameters were obtained. Identification of CNVs was performed by real-time PCR. The effect of CNVs on obesity or body composition was assessed using regression models adjusted for age, gender, and family history of obesity. Results. Gains in copy numbers of LEPR and NEGR1 were associated with decreased body mass index (BMI), waist circumference (WC), and risk of abdominal obesity, whereas gain in ARHGEF4 and CPXCR1 and the intergenic regions 12q15c, 15q21.1a, and 22q11.21d and losses in INS were associated with increased BMI and WC. Conclusion. Our results indicate a possible contribution of CNVs in LEPR, NEGR1, ARHGEF4, and CPXCR1 and the intergenic regions 12q15c, 15q21.1a, and 22q11.21d to the development of obesity, particularly abdominal obesity in Mexican children.
Asunto(s)
Moléculas de Adhesión Celular Neuronal/genética , Proteínas de Unión al ADN/genética , Obesidad Abdominal/genética , Receptores de Leptina/genética , Composición Corporal/genética , Índice de Masa Corporal , Peso Corporal/genética , Niño , Variaciones en el Número de Copia de ADN/genética , ADN Intergénico/genética , Femenino , Proteínas Ligadas a GPI/genética , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Humanos , Masculino , México , Obesidad Abdominal/fisiopatología , Factores de Intercambio de Guanina Nucleótido Rho/genética , Circunferencia de la Cintura/genéticaRESUMEN
AIMS/HYPOTHESIS: Childhood obesity is a major public health problem in Mexico, affecting one in every three children. Genome-wide association studies identified genetic variants associated with childhood obesity, but a large missing heritability remains to be elucidated. We have recently shown a strong association between a highly polymorphic copy number variant encompassing the salivary amylase gene (AMY1 also known as AMY1A) and obesity in European and Asian adults. In the present study, we aimed to evaluate the association between AMY1 copy number and obesity in Mexican children. METHODS: We evaluated the number of AMY1 copies in 597 Mexican children (293 obese children and 304 normal weight controls) through highly sensitive digital PCR. The effect of AMY1 copy number on obesity status was assessed using a logistic regression model adjusted for age and sex. RESULTS: We identified a marked effect of AMY1 copy number on reduced risk of obesity (OR per estimated copy 0.84, with the number of copies ranging from one to 16 in this population; p = 4.25 × 10(-6)). The global association between AMY1 copy number and reduced risk of obesity seemed to be mostly driven by the contribution of the highest AMY1 copy number. Strikingly, all children with >10 AMY1 copies were normal weight controls. CONCLUSIONS/INTERPRETATION: Salivary amylase initiates the digestion of dietary starch, which is highly consumed in Mexico. Our current study suggests putative benefits of high number of AMY1 copies (and related production of salivary amylase) on energy metabolism in Mexican children.
Asunto(s)
Metabolismo de los Hidratos de Carbono/genética , Obesidad/genética , alfa-Amilasas Salivales/metabolismo , Índice de Masa Corporal , Niño , Femenino , Predisposición Genética a la Enfermedad/genética , Variación Genética , Estudio de Asociación del Genoma Completo , Humanos , Modelos Logísticos , Masculino , México/epidemiología , Obesidad/epidemiología , Salud Pública , alfa-Amilasas Salivales/genéticaRESUMEN
BACKGROUND: Recent genome wide association studies (GWAS) and previous positional linkage studies have identified more than 50 single nucleotide polymorphisms (SNPs) associated with obesity, mostly in Europeans. We aimed to assess the contribution of some of these SNPs to obesity risk and to the variation of related metabolic traits, in Mexican children. METHODS: The association of six European obesity-related SNPs in or near FTO, NPC1, ENPP1, NEGR1, GNPDA2 and MC4R genes with risk of obesity was tested in 1,463 school-aged Mexican children (N(cases) = 514; N(controls) = 949). We also assessed effects of these SNPs on the variation of body mass index (BMI), fasting serum insulin levels, fasting plasma glucose levels, total cholesterol and triglyceride levels, in a subset of 1,171 nonobese Mexican children. RESULTS: We found a significant effect of GNPDA2 rs10938397 on risk of obesity (odds ratio [OR] = 1.30; P = 1.34 × 10-3). Furthermore, we found nominal associations between obesity risk or BMI variation and the following SNPs: ENPP1 rs7754561, MC4R rs17782313 and NEGR1 rs2815752. Importantly, the at-risk alleles of both MC4R rs17782313 and NPC1 rs1805081 showed significant effect on increased fasting glucose levels (ß = 0.36 mmol/L; P = 1.47 × 10(-3)) and decreased fasting serum insulin levels (ß = -0.10 µU/mL; P = 1.21 × 10(-3)), respectively. CONCLUSION: Our present results suggest that some obesity-associated SNPs previously reported in Europeans also associate with risk of obesity, or metabolic quantitative traits, in Mexican children. Importantly, we found new associations between MC4R and fasting glucose levels, and between NPC1 and fasting insulin levels.