title: Genotype-phenotype correlations of TGFBI p.Leu509Pro, p.Leu509Arg, p.Val613Gly, and the allelic association of p.Met502Val-p.Arg555Gln mutations.
abstract: OBJECTIVE
  Investigate the genotype-phenotype correlations for five TGFBI (transforming growth factor, beta-induced) mutations including one novel pathogenic variant and one complex allele affecting the fourth FAS1 domain of keratoepithelin, and their potential effects on the protein's structure.
  
  
  METHODS
  Three unrelated families were clinically diagnosed with lattice corneal dystrophy (CD) and one with an unclassified CD of Bowman's layer. Mutations in the TGFBI gene were detected by direct sequencing, and the functional impact of each variant was predicted using in silico algorithms. Corneal phenotypes, including histological examinations, were compared with the literature data. Furthermore, molecular modeling studies of these mutations were performed.
  
  
  RESULTS
  Two distinct missense mutations affecting the same residue at position 509 of keratoepithelin: p.Leu509Pro (c.1526T>C) and p.Leu509Arg (c.1526T>G) were found to be associated with a lattice-type CD. The novel p.Val613Gly (c.1828T>G) TGFBI mutation was found in a sporadic case of an Algerian individual affected by lattice CD. Finally, the Bowman's layer CD was linked to the association in cis of the p.Met502Val and p.Arg555Gln variants, leading to the reclassification of this CD as atypical Thiel-Behnke CD. Structural modeling of these TGFBI mutations argues in favor of these mutations being responsible for instability and/or incorrect folding of keratoepithelin, predictions that are compatible with the clinical diagnoses.
  
  
  CONCLUSIONS
  Description of a novel TGFBI mutation and a complex TGFBI allele further extends the mutational spectrum of TGFBI. Moreover, we show convincing evidence that TGFBI mutations affecting Leu509 are linked to the lattice phenotype in two unrelated French families, contrasting with findings previously reported. The p.Leu509Pro was reported to be associated with both amyloid and non-amyloid aggregates, whereas p.Leu509Arg has been described as being responsible for Epithelial Basement Membrane Dystrophy (EBMD).
authors: Inserm, U1016, Institut Cochin, CNRS, UMR 8104, Université Paris-Descartes, Paris, France.
authors: Florence
authors: F
authors: Niel-Butschi
authors: Bernadette
authors: B
authors: Kantelip
authors: Justyna
authors: J
authors: Iwaszkiewicz
authors: Vincent
authors: V
authors: Zoete
authors: Mathieu
authors: M
authors: Boimard
authors: Marc
authors: M
authors: Delpech
authors: Jean-Louis
authors: JL
authors: Bourges
authors: Gilles
authors: G
authors: Renard
authors: François
authors: F
authors: D'Hermies
authors: Pierre-Jean
authors: PJ
authors: Pisella
authors: Christian
authors: C
authors: Hamel
authors: Bernard
authors: B
authors: Delbosc
authors: Sophie
authors: S
authors: Valleix
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