Genotype-phenotype correlation of TGFBI corneal dystrophies in Polish patients

To analyze genotype-phenotype correlation in patients originating from Polish population with the transforming growth factor beta induced (TGFBI) corneal dystrophies.

Sixty affected and 31 unaffected individuals from 15 unrelated Polish families were included in the study. The clinical diagnosis was based on the slit-lamp exam, 1310 nm time domain and 1310 nm swept source spectral domain optical coherence tomography (OCT). Histopathologic analysis was performed on 10 available corneal buttons. Exons of the TGFBI gene were screened for mutations with polymerase chain reaction (PCR) and direct DNA sequencing.

We found the lattice phenotype dominant compared to the granular one in the Polish population (41:16 patients; lattice:granular). We identified five distinct mutations responsible for TGFBI corneal dystrophies (R124R, R124H, R555W, R555Q, and H626R). There was a strong genotype-phenotype correlation in the case of R124R and R555W mutations, while there was a distinct phenotypic heterogeneity in the case of the H626R mutation. OCT analysis revealed that the reflectivity, location and pattern of the corneal deposits were different among the TGFBI corneal dystrophies. The advantage of spectral swept source OCT over time-domain OCT scans is a more distinct visualization of the Bowman's layer area and deposits located under the epithelium.

This study underlines the role of comprehensive phenotype-genotype analysis in TGFBI corneal dystrophies, describes for the first time the TGFBI mutation spectrum in a Polish population and reveals phenotypic heterogeneity in the case of the H626R mutation.