RAI1 and Smith-Magenis syndrome: SMS is a multiple congenital anomalies/mental retardation disorder associated with a heterozygous interstitial deletion on chromosome 17p11.2 in >95% of patients (Edelman et al., 2007; Greenberg et al., 1991; Smith et al., 1986), or rarely with point mutations in Retinoic acid induced 1 (Rai1), a gene located within this deletion (Slager et al., 2003).