Description
We report a highly-penetrant form of obesity, initially observed in 31 heterozygous carriers of a 593kb or larger deletion at 16p11.2 from amongst subjects ascertained for cognitive deficits. Nineteen similar deletions were identified from GWAS data in 16053 individuals from 8 European cohorts; such deletions was absent from healthy non-obese controls and accounted for 0.7% of our morbid obesity cases (p = 6.4x10-8, OR = 43). These findings highlight a promising strategy for identifying missing heritability in obesity and other complex traits, in which insights from rare extreme cases can be used to elucidate the basis for more common phenotypes.