Owing to our focus on common CNVs, the role of rare deletions or duplications has only been addressed here, by exploring selected loci harbouring known rare CNVs in extreme obese patients (20,21). In order to comprehensively investigate whether certain rare CNVs [e.g. large (>1 Mb) CNVs (cf. 22)] predispose to obesity, a more comprehensive quality control (QC) and validation of each single CNV call as well as a much larger adequately powered analysis sample is needed. It is conceivable that such assessments will become feasible within large-scale consortia such as GIANT [Genetic Investigation of ANthropometric Traits (8)].
