KSR2 and obesity due to melanocortin 4 receptor deficiency: To comprehensively address whether genetic variants in KSR2 contribute to obesity, we sequenced the coding region and intron/exon boundaries of KSR2 in 1,770 individuals of mixed European descent with severe, early-onset obesity (mean body mass index [BMI] standard deviation score 3.5; age of onset <10 years) who were recruited to the Genetics of Obesity Study (GOOS) (Farooqi et al., 2003).