RAI1 and obesity due to melanocortin 4 receptor deficiency: We found that all affected members of both families F38 and F40 did not have the additional symptoms typical for SMS patients with mutations in RAI1. In particular, we did not observe any craniofacial and skeletal abnormalities (brachycephaly, midface hypoplasia, broad square-shaped face, a tented upper lip, deep-set eyes, brachydactylia, short stature) and obesity.