<unk>  is a chromosomal condition related to low copy repeats of specific segments of chromosome 17. Most people with SMS have a deletion of genetic material from a specific region of chromosome 17 (17p11.2). Although this region contains multiple genes, recently researchers discovered that the loss of one particular gene the retinoic acid induced 1 or RAI1 is responsible for most of the characteristic features of this condition. Also, other genes within the chromosome 17 contribute to the variability and severity of the clinical features. The loss of other genes in the deleted region may help explain why the features of<unk>  vary among affected individuals. A small percentage of people with<unk>  have a mutation in the RAI1 gene instead of a chromosomal deletion. These deletions and mutations lead to the production of an abnormal or nonfunctional version of the RAI1 protein. RAI1 is a transcription factor that regulates the expression of multiple genes, including several that are involved in controlling circadian rhythm, such as CLOCK. The groups led by James Lupski (Baylor College of Medicine) and Sarah Elsea (Virginia Commonwealth University) are in the process of studying the exact function of this gene in relation to<unk> . SMS is typically not inherited. This condition usually results from a genetic change that occurs during the formation of reproductive cells (eggs or sperm) or in early fetal development. People with<unk>  most often have no history of the condition in their family.
Smith–Magenis syndrome
Marshall–Smith syndrome
Wilson–Turner syndrome
Bardet–Biedl syndrome
Beckwith–Wiedemann syndrome
Smith–Lemli–Opitz syndrome
Kapur–Toriello syndrome
Smith Martin Dodd syndrome