A novel mutation of the ARX gene in a male with nonsyndromic mental retardation.
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.
Troester
Matthew M
MM
Children's Health Center, St. Joseph's Hospital and Medical Center, Barrow Neurological Institute Phoenix, Arizona, USA.
Trachtenberg
Tamara
T
Narayanan
Vinodh
V
D002675:Child, Preschool; D041321:Chromosomes, Human, X; D004252:DNA Mutational Analysis; D005091:Exons; D017353:Gene Deletion; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008297:Male; D038901:X-Linked Intellectual Disability / Q000235:genetics*; D010375:Pedigree; D014157:Transcription Factors / Q000235:genetics*
C469264:ARX protein, human; D018398:Homeodomain Proteins; D014157:Transcription Factors