XLMR Related Protein, Neurite Extension (XPN)

The disease is caused by mutations affecting the gene represented in this entry. A chromosomal aberration involving KIAA2022 is found in patients with severe mental retardation. Pericentric inversion inv(X)(p22.3;q13.2) with P2RY8 leading to inactivation of KIAA2022.Disease description:A disorder characterized by significantly below average general intellectual functioning associated with impairments in adaptive behavior and manifested during the developmental period. MRX98 patients show delayed psychomotor development, absent or poor speech development, and postnatal growth retardation, often with microcephaly. Some patients show autistic behavioral features, such as stereotypic hand movements and repetitive behaviors. Additional, more variable features include spasticity, axial hypotonia, seizures, drooling, gastroesophageal reflux, and lack of sphincter control