Isolated foveal hypoplasia with secondary nystagmus and low vision is associated with a homozygous SLC38A8 mutation

Eur J Hum Genet. 2014 May;22(5):703-6. doi: 10.1038/ejhg.2013.212. Epub 2013 Sep 18.

Abstract

Foveal hypoplasia, always accompanied by nystagmus, is found as part of the clinical spectrum of various eye disorders such as aniridia, albinism and achromatopsia. However, the molecular basis of isolated autosomal recessive foveal hypoplasia is yet unknown. Individuals of apparently unrelated non consanguineous Israeli families of Jewish Indian (Mumbai) ancestry presented with isolated foveal hypoplasia associated with congenital nystagmus and reduced visual acuity. Genome-wide homozygosity mapping followed by fine mapping defined a 830 Kb disease-associated locus (LOD score 3.5). Whole-exome sequencing identified a single missense mutation in the homozygosity region: c.95T>G, p.(Ile32Ser), in a conserved amino acid within the first predicted transmembrane domain of SLC38A8. The mutation fully segregated with the disease-associated phenotype, demonstrating an ∼10% carrier rate in Mumbai Jews. SLC38A8 encodes a putative sodium-dependent amino-acid/proton antiporter, which we showed to be expressed solely in the eye. Thus, a homozygous SLC38A8 mutation likely underlies isolated foveal hypoplasia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Amino Acid Transport Systems, Neutral / genetics*
  • Child
  • Child, Preschool
  • DNA Mutational Analysis
  • Eye Diseases, Hereditary / complications*
  • Eye Diseases, Hereditary / genetics*
  • Female
  • Fovea Centralis / abnormalities*
  • Gene Expression Regulation
  • Genetic Linkage
  • Genome-Wide Association Study
  • Homozygote*
  • Humans
  • Infant
  • Male
  • Middle Aged
  • Mutation*
  • Nystagmus, Congenital / complications*
  • Nystagmus, Congenital / genetics*
  • Pedigree
  • Phenotype
  • Vision, Low / etiology*
  • Young Adult

Substances

  • Amino Acid Transport Systems, Neutral
  • Slc38a8 protein, human

Supplementary concepts

  • Foveal Hypoplasia, Isolated