Mice with a deletion of Nhlh2 show adult-onset obesity [19], suggesting that the obese phenotype of PWS patients may involve SNORD116-mediated regulation of NHLH2. Considering the human clinical cases and the mouse Snord116p-/m+ knockout model together, a strong case can be made that deletion of SNORD116@ is the most plausible mechanism for the development of the main clinical phenotypes of PWS. This evidence concerns the gene NHLH2 and obesity due to melanocortin 4 receptor deficiency.