Study of the RAX Gene in Patients With Microphthalmia/Anophthalmia/Coloboma

Abstract

Abstract: : Purpose: Microphthalmia, anophthalmia, and coloboma (MAC) are thought to have a significant genetic component. RAX is a homeobox gene that is expressed early in the developing retina and is important in retinal cell fate specification as well as in stem cell proliferation. Voronina et al. identified a single patient who was a compound heterozygote for autosomal recessive RAX mutations within a group of 75 anophthalmia and/or microphthalmia patients (Hum Mol Genet 2004; 13:315–322). These authors also reported two polymorphisms in the first and third exons. We screened a group of 25 MAC patients for RAX mutations. Methods: We used standard PCR and automated sequencing techniques to amplify and sequence each of the three RAX exons. Patientsâ€^TM charts were reviewed for clinical information. Results: In addition to the polymorphisms described by Voronina et al., we identified a prevalent single nucleotide change (106 G>A) in the first exon that results in a glutamine to lysine alteration in the primary amino acid sequence. We further identified two other single nucleotide variations, also in the first exon, in two separate patients (153 A>C and 146 G>A), each resulting in an alteration in the primary sequence. We found no apparent correlation between the observed nucleotide variations and patient phenotype. Conclusions: Sequence variations in RAX are common in our particular cohort of patients with major congenital ocular malformations and may play a role in the pathogenesis of these abnormalities.

Keywords: gene screening • infant vision • transcription factors