Abstract
Purpose: :
Corneal dystrophies are common inherited disorders in which corneal transparency and refractive index are affected due to the accumulation of deposits within the different corneal layers. Most CDs are inherited in an autosomal dominant fashion and mutations in the TGFBI gene at chromosome 5q31 originate the majority of CDs affecting the stromal layer. The TGFBI R124H mutation is characteristic of GCD type 2 or Avellino CD cases from different countries. The objective of this work is to report a novel genotype associated to this CD.
Methods: :
Slitlamp examination and corneal phenotypic characterization; DNA collection from the proband, PCR amplification of exons 4,11,12, and 14 of the TGFBI gene and subsequent nucleotidic sequencing of PCR products in the proband and 57 healthy controls (114 alleles). Histopathologic examination of the excised corneal button was performed.
Results: :
Multiple polymorphic stromal opacities, from subepithelial to deep stroma, some coalescent, mainly central, were found. On retroillumination, peripheral refractive lines with a lattice patern were observed. Clinical diagnosis was compatible with Avellino corneal dystrophy. Histopathologic examination revealed stromal deposits that stained with the Congo red and Masson trichrome stains, and negative for alcian blue, confirming the clinical diagnosis. Screening of TGFBI gene demonstrated a novel heterozygous c.1649T>C mutation at exon 12, predicting a novel, p.Leu550Pro; the mutation that was not found in unaffected family members nor in 114 control alleles
Conclusions: :
We report a novel genotypic association for Avellino corneal dystrophy, which was diagnosed on clinical basis and confirmed by histopathology. The novel p.Leu550Pro mutation expands our knowledge on molecular genetics of corneal stromal dystrophies.
Keywords: genetics • cornea: clinical science • cornea: stroma and keratocytes