Intellectual disability (ID) is characterized by significant limitations in cognitive abilities and social/behavioral adaptive skills. It is estimated that 1-3% of the general population is affected with ID. Intellectual disability is one of the primary reasons for pediatric, neurologic, and genetic referrals.
Intellectual disability can result from both environmental circumstances and genetic causes. Genetic causes, which account for up to 50% of moderate-severe cases, include chromosomal anomalies, specific syndromes, and single gene disorders.
Approximately 10% of the protein-encoding genes on the X chromosome have been implicated in XLID. Although the numbers of mutations and reported families are small, collectively the impact of these genes is significant. This panel includes analysis of 114 X-linked genes that are known to be involved in syndromal and nonsyndromal intellectual disability.
A majority of individuals with XLID are non-syndromal with no other features to assist in the diagnosis. Because of the number of genes involved, it is very difficult to identify which X-linked gene may be responsible for the phenotype in any given patient. Our simultaneous testing of all known XLID genes in a single study provides a significant diagnostic advantage over single gene sequencing.