ARX mutation c.428-451dup (24bp) in a Brazilian family with X-linked mental retardation.

The recently identified gene ARX (Aristalles-Related Homeobox) codifies the ARX protein, an important transcript factor that belongs to one of the three largest classes of homeoproteins, the paired (Prd) class. Several mutations have been identified in ARX gene, which is responsible for a wide spectrum of phenotypes, including syndromic as well as non syndromic forms of mental retardation. One of the mutations, the c.428-451 dup (24 bp) is the most frequent identified in the ARX gene. This duplication leads to an expansion of the second polyalanine tract of ARX protein. We have reported the identification of a Brazilian family segregating the c.428-451 dup (24 bp) in ARX gene.