Genome-wide SNP and CNV analysis identifies common and low-frequency variants associated with severe early-onset obesity

Sadaf Farooqi, Inês Barroso and colleagues report genome-wide SNP and CNV association analyses for severe obesity in children, selected at the extreme of the distribution for body mass index. They identify four loci newly associated with severe obesity, an enrichment of rare CNVs in severely obese cases and overlap in the loci associated with severe obesity in children and with BMI and obesity in the general population. Common and rare variants associated with body mass index (BMI) and obesity account for 3 s.d. from the mean) of the BMI distribution and 5,380 controls. Evaluation of 29 SNPs ( P < 1 × 10 −5 ) in an additional 971 severely obese children and 1,990 controls identified 4 new loci associated with severe obesity ( LEPR , PRKCH , PACS1 and RMST ). A previously reported 43-kb deletion at the NEGR1 locus was significantly associated with severe obesity ( P = 6.6 × 10 −7 ). However, this signal was entirely driven by a flanking 8-kb deletion; absence of this deletion increased risk for obesity ( P = 6.1 × 10 −11 ). We found a significant burden of rare, single CNVs in severely obese cases ( P < 0.0001). Integrative gene network pathway analysis of rare deletions indicated enrichment of genes affecting G protein–coupled receptors (GPCRs) involved in the neuronal regulation of energy homeostasis.