ARX-associated Diseases - ARX

Klinische Symptomatik

The clinical phenotype of patients with a mutation in the ARX gene is highly variable. Mutations in the ARX gene were found in patients with West-Syndrome, as well as a similar condition with myoclonic seizures, spasticity and mental retardation (XMESID syndrome). ARX mutations were also detected in another condition, the Partington syndrome or MRXS1, characterised by mild to moderate mental retardation and episodic dystonic movements of the hands with dysarthria and ataxia. XLAG syndrome (X-linked lissencephaly with abnormal genitalia) shows mutations in the ARX gene as well. The clinical phenotype of this syndrome is indicated by microcephaly, seizures, abnormal regulation of temperature and underdeveloped genitals. A lissencephaly and agenesis of the corpus callosum is seen by MRT.

Genetik

The ARX gene (aristaless related homeobox gene) belongs to the homeobox gene family and codes for an aristaless-related protein class II, which is expressed in the central and peripheral nervous system. ARX is located on the short arm of the X-chromosome (Xp22.11). It is composed of 1689 nucleotides which are scattered over 5 exons. The protein plays a major role in the differentiation of the brain in the early embryonal development.