Exclusion of AR-CHED from the chromosome 20 region containing the PPMD and AD-CHED loci

Ophthalmic Genet. 1999 Dec;20(4):243-9. doi: 10.1076/opge.


Congenital hereditary endothelial dystrophy (CHED) is a disorder of the corneal endothelium and has been recognized to segregate in families with both autosomal dominant (AD) and autosomal recessive (AR) modes of transmission. AD-CHED has been previously linked to the pericentric region of chromosome 20. Posterior polymorphous dystrophy (PPMD), a corneal endothelial disorder showing phenotypic overlap with CHED, has also been previously genetically mapped to this region. The genetic interval containing AD-CHED is within the larger genetic interval containing the PPMD locus. This study sought to determine whether AR-CHED segregating in a consanguineous Saudi Arabian pedigree is linked to the previously mapped and overlapping loci for AD-CHED and PPMD on the pericentric region of chromosome 20. Forty members of a consanguineous Saudi Arabian pedigree segregating AR-CHED were ascertained. Short tandem-repeat polymorphic markers from the 20 cM interval on chromosome 20 containing both the PPMD and AD-CHED loci were used to genotype these individuals. LOD score analysis of the genotype data with the MENDEL software package utilizing a model of autosomal recessive inheritance with complete penetrance showed exclusion of CHED from the entire PPMD/AD-CHED interval by utilizing overlapping intervals of LOD scores of at least -2. The results obtained demonstrate that AR-CHED is not allelic to either AD-CHED or PPMD, although it has been proposed that AD-CHED may be allelic to PPMD. Thus, there are at least two genes responsible for CHED and PPMD.

Publication types

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

MeSH terms

  • Chromosome Mapping
  • Chromosomes, Human, Pair 20 / genetics*
  • Corneal Diseases / genetics*
  • Corneal Diseases / pathology
  • Corneal Dystrophies, Hereditary / genetics*
  • Corneal Dystrophies, Hereditary / pathology
  • Endothelium, Corneal / abnormalities*
  • Family Health
  • Female
  • Genes, Dominant
  • Genes, Recessive*
  • Genetic Linkage
  • Genotype
  • Haplotypes
  • Humans
  • Lod Score
  • Male
  • Microsatellite Repeats
  • Pedigree