In our study, 5 previously reported mutations of the TGFBI gene – R124C, R124H, R124L (exon 4), R555W, R555Q (exon 12) – were analyzed using polymerase chain reaction followed by restriction digestion in 48 individuals from 19 unrelated families with different forms of corneal dystrophy from different regions of Ukraine. The R555W mutation was detected in 6 patients from 4 families with granular corneal dystrophy. The R124C mutation was detected in 1 unaffected 10-year-old individual and in 24 patients from 8 families with lattice corneal dystrophy. As far as the R124C mutation detected in 1 patient with clinically diagnosed Reis-Bucklers corneal dystrophy is concerned, we concluded that this patient was misdiagnosed. The obtained results show that TGFBI gene mutation analysis is important as well for the early differential diagnosis of corneal dystrophies and genetic consulting in high-risk families.

Purpose: To report a novel L558P mutation of the human transforming growth factor β-induced (TGFBI) gene found in Ukrainian families with atypical corneal dystrophy (CD). Methods: Genomic DNA was extracted from peripheral leukocytes of 12 members of 4 unrelated families with atypical CD. We performed genotype analysis of these families with microsatellite markers surrounding the TGFBI locus. Exons of the TGFBI gene were amplified by polymerase chain reaction (PCR), and directly sequenced in 5 patients of 4 unrelated families. We utilized a simple PCR/restriction fragment length polymorphism-based technique for L558P mutation identification. Fifty normal individuals were also analyzed as controls. These assays were complemented by histological analysis of available corneal buttons excised during penetrating keratoplasty. Results: A heterozygous single-base-pair transition (CTC to CCC, leucine to proline) at codon 558 in exon 12 of the TGFBI gene (L558P) was detected in 10 individuals. Eight are affected, and 2 are teenagers with no clinical manifestation of the disease as yet. The mutation was not found in 2 healthy individuals from 2 high-risk CD families, nor in 50 normal controls. Histopathological examination identified amyloid deposits, mostly in the posterior central cornea. Haplotype analysis provided evidence of a common founder of the L558P mutation. The mutation works on the protein level by disrupting an α-helix, which is crucial for the normal functioning of keratoepithelin. Conclusion: A novel L558P mutation in the TGFBI gene causes an atypical type of stromal CD.

In this study Arg124Cys (exon 4), Thr538Arg, Ala546Thr, Arg555Thr, ARg55Gln (exon 12), His626Arg (exon 14) mutations of the TGFBI gene were analyzed using polymerase chain reaction followed by restriction digestion in 91 patients with different forms of corneal dystrophy and 31 clinically healthy individuals from 49 unrelated families. Our results show that TGFBI gene mutations analysis is important for differential diagnostics of corneal dystrophies with prognostic and therapeutic implications as well as for genetic consulting in high risk families.