Cosegregation and functional analysis of mutant ABCR (ABCA4) alleles in families that manifest both Stargardt disease and age-related macular degeneration

Hum Mol Genet. 2001 Nov 1;10(23):2671-8. doi: 10.1093/hmg/10.23.2671.

Abstract

Mutations in ABCR (ABCA4) have been reported to cause a spectrum of autosomal recessively inherited retinopathies, including Stargardt disease (STGD), cone-rod dystrophy and retinitis pigmentosa. Individuals heterozygous for ABCR mutations may be predisposed to develop the multifactorial disorder age-related macular degeneration (AMD). We hypothesized that some carriers of STGD alleles have an increased risk to develop AMD. We tested this hypothesis in a cohort of families that manifest both STGD and AMD. With a direct-sequencing mutation detection strategy, we found that AMD-affected relatives of STGD patients are more likely to be carriers of pathogenic STGD alleles than predicted based on chance alone. We further investigated the role of AMD-associated ABCR mutations by testing for expression and ATP-binding defects in an in vitro biochemical assay. We found that mutations associated with AMD have a range of assayable defects ranging from no detectable defect to apparent null alleles. Of the 21 missense ABCR mutations reported in patients with AMD, 16 (76%) show abnormalities in protein expression, ATP-binding or ATPase activity. We infer that carrier relatives of STGD patients are predisposed to develop AMD.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / genetics*
  • Adenosine Triphosphate / metabolism
  • Aging / physiology
  • Alleles*
  • Blotting, Western
  • Cell Line
  • DNA / chemistry
  • DNA / genetics
  • DNA Mutational Analysis
  • Eye Diseases, Hereditary / genetics*
  • Family Health
  • Female
  • Humans
  • Macular Degeneration / genetics*
  • Male
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mutagenesis
  • Mutation
  • Pedigree
  • Plasmids / genetics
  • Protein Binding
  • Transfection

Substances

  • ABCA4 protein, human
  • ATP-Binding Cassette Transporters
  • Membrane Proteins
  • Adenosine Triphosphate
  • DNA