RAI1 and Intellectual disability: Smith-Magenis syndrome (SMS) is a genetic disorder caused by both heterozygous deletions at the chromosome band 17p11.2 region or heterozygous pathogenic variants in the Retinoic Acid-Induced 1 (RAI1) gene, which is characterized by multiple congenital anomalies, sleep disturbances, behavioral impairment, and a variable level of intellectual disability [1].