15q13.3 microdeletion syndrome
is a type of contiguous gene deletion syndrome. Individuals with this microdeletion may have very different signs and symptoms from other affected individuals (even within the same family), or no symptoms at all. Features of the condition may include mild to moderate mental retardation, learning difficulties, or normal intelligence; autism; epilepsy (recurring seizures); and mental illness (such as schizophrenia or bipolar disorder). Various dysmorphic (abnormally formed) features have been reported, but there are no consistent physical features among individuals who have the condition. It is caused by a tiny deletion (microdeletion) on the long arm of chromosome 15 that spans at least 6 genes; the features of the syndrome are caused by the absence of these genes, which are usually necessary for normal growth and development. It can be inherited in an autosomal dominant manner with reduced penetrance, or can occur as a new (de novo) deletion. Treatment typically focuses on individual signs and symptoms (such as medication for seizures) when possible. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.