OBJECTIVES: The mutations in gene for the melanocortin-4 receptor (MC4R) are the most common etiology factors of monogenic obesity development. Recently, it has been shown that current life style has a significant impact on the phenotype of MC4R mutation carriers - increases the penetrance of the mutations. We aimed to study the impact of the current age on the time of obesity onset among MC4R mutation carriers. METHODS: DNA analysis of the MC4R gene was performed in 268 unrelated Slovak and Moravian obese children and adolescents 18 years and 28 blood relatives >18 years of the probands with a mutation. RESULTS: Three different previously described heterozygous loss of function MC4R mutations (p.Ser19Alafs*34, p.Ser127Leu, and p.Gly181Asp) were found in 3 <18 years probands, 3 adult probands, and 6 adult obese/overweight family relatives. The age of obesity onset in mutation carriers was 1 year in all probands in the children group and 1-35 years (median 11 years) in adults. The age of the obesity onset significantly correlated (R=0.809, p=0.028) with the current age in all of the MC4R mutation carriers. CONCLUSIONS: The age of obesity onset in the present child generation of MC4R mutation carriers is decreasing compared to the age of onset in their parents' generation. This is in agreement with similarly increasing penetrance of obesity in MC4R mutation carriers and it points out to escalation of obesogenic potential of environment.

• Klíčová slova
• MC4R mutation carriers, adolescents., children, obesity,
• MeSH
• dítě MeSH
• dospělí MeSH
• fenotyp MeSH
• genetická predispozice k nemoci MeSH
• genetické asociační studie MeSH
• heterozygot MeSH
• kojenec MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mutace * MeSH
• mutační analýza DNA MeSH
• obezita dětí a dospívajících diagnóza   epidemiologie   genetika   MeSH
• předškolní dítě MeSH
• receptor melanokortinový typ 4 genetika   MeSH
• rizikové faktory MeSH
• studie případů a kontrol MeSH
• věk při počátku nemoci MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• kojenec MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika epidemiologie   MeSH
• Slovenská republika epidemiologie   MeSH
• Názvy látek
• MC4R protein, human MeSH Prohlížeč
• receptor melanokortinový typ 4 MeSH

The most common etiology of non-syndromic monogenic obesity are mutations in gene for the Melanocortin-4 receptor (MC485) with variable prevalence in different countries (1.2-6.3 % of obese children). The aim of our study was 1) to search for MC4R mutations in obese children in Slovakia and compare their prevalence with other European countries, and 2) to describe the phenotype of the mutation carriers. DNA analysis by direct Sanger sequencing of the coding exons and intron/exon boundaries of the MC4R gene was performed in 268 unrelated Slovak children and adolescents with body mass index above the 97(th) percentile for age and sex and obesity onset up to 11 years (mean 4.3+/-2.8 years). Two different previously described heterozygous loss of function MC4R variants (i.e. p.Ser19Alafs*34, p.Ser127Leu) were identified in two obese probands, and one obese (p.Ser19Alafs*34), and one lean (p.Ser127Leu) adult family relatives. No loss of function variants were found in lean controls. The prevalence of loss-of-function MC4R variants in obese Slovak children was 0.7 %, what is one of the lowest frequencies in Europe.

• MeSH
• dítě MeSH
• fenotyp MeSH
• genotyp MeSH
• heterozygot MeSH
• lidé MeSH
• mladiství MeSH
• mutační analýza DNA MeSH
• obezita dětí a dospívajících genetika   MeSH
• předškolní dítě MeSH
• receptor melanokortinový typ 4 genetika   MeSH
• studie případů a kontrol MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Geografické názvy
• Slovenská republika MeSH
• Názvy látek
• MC4R protein, human MeSH Prohlížeč
• receptor melanokortinový typ 4 MeSH

BACKGROUND: Inactivating mutations of the hypothalamic transcription factor singleminded1 (SIM1) have been shown as a cause of early-onset severe obesity. However, to date, the contribution of SIM1 mutations to the obesity phenotype has only been studied in a few populations. In this study, we screened the functional regions of SIM1 in severely obese children of Slovak and Moravian descent to determine if genetic variants within SIM1 may influence the development of obesity in these populations. METHODS: The SIM1 promoter region, exons and exon-intron boundaries were sequenced in 126 unrelated obese children and adolescents (2-18 years of age) and 41 adult lean controls of Slovak and Moravian origin. Inclusion criteria for the children and adolescents were a body mass index standard deviation score higher than 2 SD for an appropriate age and sex, and obesity onset at less than 5 years of age. The clinical phenotypes of the SIM1 variant carriers were compared with clinical phenotypes of 4 MC4R variant carriers and with 27 unrelated SIM1 and MC4R mutation negative obese controls that were matched for age and gender. RESULTS: Seven previously described SIM1 variants and one novel heterozygous variant p.D134N were identified. The novel variant was predicted to be pathogenic by 7 in silico software analyses and is located at a highly conserved position of the SIM1 protein. The p.D134N variant was found in an 18 year old female proband (BMI 44.2kg/m2; +7.5 SD), and in 3 obese family members. Regardless of early onset severe obesity, the proband and her brother (age 16 years) did not fulfill the criteria of metabolic syndrome. Moreover, the variant carriers had significantly lower preferences for high sugar (p = 0.02) and low fat, low carbohydrate, high protein (p = 0.02) foods compared to the obese controls. CONCLUSIONS: We have identified a novel SIM1 variant, p.D134N, in 4 obese individuals from a single pedigree which is also associated with lower preference for certain foods.

• MeSH
• detekce genetických nosičů MeSH
• dítě MeSH
• fenotyp MeSH
• lidé MeSH
• mladiství MeSH
• mutace MeSH
• nepřímá kalorimetrie MeSH
• obezita etnologie   genetika   MeSH
• předškolní dítě MeSH
• preference v jídle MeSH
• receptor melanokortinový typ 4 genetika   MeSH
• represorové proteiny genetika   MeSH
• rodokmen MeSH
• studie případů a kontrol MeSH
• stupeň závažnosti nemoci MeSH
• transkripční faktory bHLH genetika   MeSH
• věk při počátku nemoci MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika etnologie   MeSH
• Slovenská republika etnologie   MeSH
• Názvy látek
• receptor melanokortinový typ 4 MeSH
• represorové proteiny MeSH
• SIM1 protein, human MeSH Prohlížeč
• transkripční faktory bHLH MeSH