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The ARX mutations: a frequent cause of X-linked mental retardation

Magdalena Nawara1, Krzysztof Szczaluba, Karine Poirier

  • 1Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, Warsaw, Poland. mnawara@imid.med.pl

American Journal of Medical Genetics. Part A
|March 9, 2006
PubMed

Insights

ARX gene mutations are a significant cause of X-linked mental retardation (XLMR). A specific ARX mutation (c.428-451 dup (24 bp)) was found in 3% of patients, suggesting widespread screening is beneficial.

Area of Science:

  • Genetics
  • Neurodevelopmental Disorders
  • Molecular Biology

Background:

  • Mutations in the ARX gene are a known cause of various forms of mental retardation (MR).
  • ARX gene dysfunction is a frequent cause of X-linked mental retardation (XLMR), second only to FMR1.
  • ARX mutations are rare in sporadic cases of MR.

Purpose of the Study:

  • To determine the frequency of ARX mutations in patients with X-linked mental retardation (XLMR).
  • To investigate the role of ARX gene mutations in the etiology of XLMR.

Main Methods:

  • Mutational analysis of the ARX gene was performed.
  • 165 probands with mental retardation, negative for FRAXA, and from families with X-linked inheritance were studied.
  • Genetic analysis identified a recurrent mutation: an in-frame 24 bp insertion (c.428-451 dup (24 bp)).

Main Results:

  • The recurrent ARX mutation c.428-451 dup (24 bp) was identified in five patients (3% of the cohort).
  • Germline mosaicism for the mutation was suggested in one family, where the mother of affected siblings did not carry the mutation.
  • These findings highlight the significant contribution of ARX mutations to XLMR.

Conclusions:

  • ARX gene mutations are a significant cause of X-linked mental retardation.
  • Screening for the specific c.428-451 dup (24 bp) ARX mutation is recommended for patients with suspected XLMR.
  • This study reinforces the importance of ARX in the genetic landscape of intellectual disability.

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