Recent rare case reports have revealed that smaller deletions of some genes on chromosome 15q11–13 can lead to features associated with PWS, even in the absence of the full diagnostic criteria for PWS, including a ~187 kb microdeletion encompassing several small nucleolar RNAs (snoRNAs) gene clusters, especially the SNORD116 cluster. This evidence concerns the gene SNORD116 and Prader-Willi syndrome.