interest because of associations of body weight and obesity with genomic imprinting (19). Differences in paternal and maternal copies of this gene have been related to body weight at birth and in adulthood in mice (20). We validated this CNV by the Affymetrix Cytogenetic platform (supplementary Fig. 4) and also found that the CNV is inherited from the father. SNCA is another gene within this CNV that has been reported to have interactive effects on response to a high-fat diet in dietary obesity (21), yet SNCA duplication is a well-known risk factor for Parkinson's disease. Several other candidate genes, such as CTSC, NOX4, DLG2, ME3, and MIPEP, are also found within the collection of rare CNVs in case subjects (Table 3). We acknowledge that this list is relatively small and that none of them occur twice in case subjects; as a result, we detected the collective association with obesity but cannot identify specific CNVs/genes that are more penetrant than others. Finally, we also did an exploratory examination to determine whether some CNVs are unique to the extremely obese case subjects. We chose a BMI threshold of 70 kg/m2, which doubles the minimum entry criteria for case subjects. However, compared with
