A novel mutation of the ARX gene in a male with nonsyndromic mental retardation.

Abstract

ARX (Aristaless-related homeobox gene) is located at Xp22. It contains 5 exons and encodes a 562-amino acid protein. The protein contains 4 polyalanine tracts, 3 of which are encoded in exon 2 and 1 in exon 4. Mutations in the ARX gene have been found in X-linked infantile spasms syndrome, Partington syndrome (mental retardation with dystonic movements of the hands), X-linked lissencephaly with abnormal genitalia, X-linked myoclonus epilepsy with spasticity and intellectual disability, and in nonsyndromic X-linked mental retardation. The most common mutation in ARX (seen in X-linked infantile spasms syndrome, Partington syndrome, and X-linked mental retardation) is a 24-bp duplication in exon 2 resulting in expansion of a polyalanine tract. Truncating mutations (deletions, frameshift, non-sense) have been found in X-linked lissencephaly with abnormal genitalia, as well as homeodomain missense mutations in X-linked myoclonus epilepsy with spasticity and intellectual disability. The authors report a novel 24-bp in-frame deletion within exon 2 of the ARX gene in a male child with X-linked mental retardation and review the spectrum of ARX mutations. This mutation results in a contraction of the second polyalanine repeat.

• Authors: Matthew M Troester, Tamara Trachtenberg, Vinodh Narayanan
• Journal: Journal of child neurology (J Child Neurol) Vol. 22 Issue 6 Pg. 744-8 (Jun 2007) ISSN: 0883-0738 [Print] United States
• PMID: 17641262 (Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ARX protein, human
• Homeodomain Proteins
• Transcription Factors

Topics

• Child, Preschool
• Chromosomes, Human, X
• DNA Mutational Analysis
• Exons
• Gene Deletion
• Homeodomain Proteins (genetics)
• Humans
• Male
• Mental Retardation, X-Linked (genetics)
• Pedigree
• Transcription Factors (genetics)