Objective: Genome-wide copy number variation (CNV) analyses have associated the 10q11.22 CNV with obesity. As the NPY4R gene is the most interesting candidate gene in this region, it was hypothesized that both genetic and structural variation in NPY4R might be implicated in the pathogenesis of obesity. Methods: In the first part of this study, 326 children and adolescents with obesity and 298 healthy lean individuals were screened for CNV in the NPY4R-containing chr.10q11.22 region. In the second part of this study, a mutation screen for variants in the NPY4R coding region was performed in 356 children and adolescents with obesity and 337 healthy lean adults.Results: Our CNV analysis demonstrated a significantly higher frequency of NPY4R containing 10q11.22 CNV loss in the patient population (P 5 0.0003), while CNV gain in this region was more prevalent in the control population (P 5 0.031). Mutation analysis resulted in the identification of 15 rare non-synonymous heterozygous variants. For two variants that could only be identified in the patient population, receptor dysfunction and thus a pathogenic effect were demonstrated. Conclusions: In conclusion, these data support an essential role for genetic and structural variation within the NPY4R gene in the pathogenesis of obesity.Obesity (2016) 24, 970-976.

Although we found evidence for moderate association between PNPLA2 tagSNPs and anthropometric and metabolic parameters in our cohort, no evidence for association between polymorphisms in the PNPLA2 gene and the presence and severity of NAFLD was identified.

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Neuropeptide Y (NPY) and its G protein-coupled NPY Y2 Receptor (NPY2R) are highly expressed in orexigenic NPY/Agouti-related peptide neurons within the arcuate nucleus, a major integrator of appetite control in the hypothalamus. As NPY and NPY2R are interesting candidate genes for obesity, we hypothesized that a genetic variation in these genes might be implicated in the pathogenesis of obesity. In the first part of this study, we performed a mutation analysis of the coding region of NPY and NPY2R with high-resolution melting curve analysis. For the highly conserved NPY gene, an extended population of 436 obese children and adolescents was screened, while for NPY2R, a smaller subset of 306 patients was used. A control population of 300 healthy individuals was screened for NPY2R to determine the general prevalence of the variants found among patients. Direct sequencing was performed for samples with melting patterns deviating from wild-type. In the second part of this study, Multiplex Amplicon Quantification (MAQ) analysis was performed in 308 obese children and adolescents to detect copy number variation (CNV) in the NPY2R region. Mutation analysis of the NPY gene led to the identification of one common missense variant (L7P; MAF 0.04), while the screening of the NPY2R gene resulted in the identification of one rare missense variant F87I in the patient population. In our CNV analysis, we could not identify copy number variation in the NPY2R region among obese children and adolescents. In summary, this study clearly indicates that genetic variation in NPY and NPY2R is at low frequency and thus does not make a major contribution to the obese phenotype in the general population.

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