The RAI1 gene is located on chromosome 17p11.2. The DNA sequence of RAI1makes a specific protein for the body, called RAI1. This protein has functions in most tissues in the human body, but it is found at its highest levels in brain tissue. There are research studies currently happening to determine the exact function of this protein and how it is involved in our development, but we know that RAI1 functions in the regulation of the expression of many other genes. Some of the current studies include mouse models, as changes in the Rai1gene in mice have been found to cause symptoms similar to those observed in humans with SMS or PTLS. Greater understanding of genes and their function is gained faster by studying mice and other animal models compared to studying humans.
Each person normally has two functional copies of the RAI1gene – one each inherited from their mother and their father. There are genetic tests that can be done to determine if there is too much or too little RAI1in the genetic code or if the sequence of RAI1has been altered. Some of these tests include a chromosomal microarray or karyotype and others involve sequencing the letters of the RAI1gene, which may be done in a gene panel test or by exome or genome sequencing.
Smith-Magenis syndrome (SMS; OMIM #182290) occurs when there is not enough functional RAI1present – this can occur when there is a chromosome deletion that includes RAI1or when there is an error in the sequence of the RAI1gene that makes RAI1 non-functional.
RAI1 Smith-Magenis Syndrome