SH2B1 and Obesity: It is interesting to note that while deletion of a region on chromosome 16 that contains SH2B1 increases the risk of obesity significantly (Bochukova et al., 2010; Walters et al., 2010), reciprocal duplication of this region results in an increase in gene dosage which influences BMI in the reverse manner (leanness) (Jacquemont et al., 2011).