title: Association and familial segregation of CTG18.1 trinucleotide repeat expansion of TCF4 gene in Fuchs' endothelial corneal dystrophy.
abstract: OBJECTIVE
  We tested the association between two intronic polymorphisms (CTG18.1 and rs613872) in TCF4 and Fuchs' endothelial corneal dystrophy (FECD), and analyzed their segregation patterns in families.
  
  
  METHODS
  We recruited 120 unrelated Caucasian subjects with FECD and 100 controls. Available family members of probands were recruited. Genotyping of the single nucleotide polymorphism (SNP) rs613872 was performed using Sanger sequencing or real-time allelic discrimination assay. The trinucleotide repeat polymorphism, CTG18.1, was genotyped using a combination of short tandem repeat assay and triplet repeat primed PCR assay. The cytosine-thymine-guanine (CTG) repeat length of ≥40 was classified as an expanded CTG18.1 allele. Association of the two loci with FECD was evaluated. Segregation in 29 families was examined.
  
  
  RESULTS
  The two polymorphisms are in linkage disequilibrium (r(2) = 0.65 in cases and 0.31 in controls). Significant associations were found between FECD and rs613872 (P = 3.1 × 10(-17)), expanded CTG18.1 allele (P = 6.5 × 10(-25)), and their haplotypes (P = 5.9 × 10(-19)). The odds ratio (OR) of each copy of the rs613872 G allele for FECD was estimated to be 9.5 (95% confidence interval [CI], 5.1-17.5). The OR of each copy of the CTG18.1 expanded allele was estimated to be 32.3 (95% CI, 13.4-77.6). The expanded CTG 18.1 allele cosegregated with the trait in 52% (15/29) of families with complete penetrance and 10% (3/29) with incomplete penetrance.
  
  
  CONCLUSIONS
  We report, to our knowledge, the first independent replication of the expanded CTG 18.1 allele conferring significant risk for FECD (>30-fold increase). The expanded allele cosegregates with the trait with complete penetrance in a majority of families, but we also document cases of incomplete penetrance.
authors.affiliation: University of Texas Southwestern Medical Center, Department of Ophthalmology, Dallas, Texas.
authors.forename: V Vinod
authors.initials: VV
authors.lastname: Mootha
authors.forename: Xin
authors.initials: X
authors.lastname: Gong
authors.forename: Hung-Chih
authors.initials: HC
authors.lastname: Ku
authors.forename: Chao
authors.initials: C
authors.lastname: Xing
mesh_terms: D000368:Aged; D000483:Alleles; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics* / Q000378:metabolism; D004247:DNA / Q000235:genetics*; D005260:Female; D005642:Fuchs' Endothelial Dystrophy / Q000235:genetics* / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D010375:Pedigree; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D000073940:Transcription Factor 4; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C532096:TCF4 protein, human; D000073940:Transcription Factor 4; D014157:Transcription Factors; D004247:DNA
keywords: Fuchs' dystrophy; TCF4; genetics