Detailed phenotypic description of stromal corneal dystrophy in a large pedigree carrying the uncommon TGFBI p.Ala546Asp pathogenic variant

Abstract

ABSTRACT Purpose The purpose of this study is to describe the corneal clinical spectrum and the intrafamilial phenotypic differences in an extended pedigree suffering from stromal corneal dystrophy due to the rare p.Ala546Asp mutation in TGFBI. Methods A total of 15 members from a four-generation Mexican family were ascertained for clinical and genetic assessment. All individuals underwent slit-lamp biomicroscopic examination and an extensive ophthalmological examination including corneal topography (OCULUS Pentacam® AXL), corneal biomechanics (OCULUS Corvis ST), and corneal confocal biomicroscopy (Heidelberg Engineering®). A total of 10 individuals carried the heterozygous c.1637C>A (p. Ala546Asp) mutation at TGFBI exon 12. Results Nine out of 10 mutation positive patients were available for clinical characterization. The mean age was 35.5 years, with the youngest and the eldest ones being 3 years old and 62 years old, respectively. The median age of onset of the symptoms was 19.7 years. Five (55.6%) patients presented with a predominantly granular corneal dystrophy type 2 (GCD2) phenotype, one presented with a lattice corneal dystrophy (LCD) phenotype, and one with a granular corneal dystrophy type 1 (GCD1) phenotype. Interestingly, two mutation positive subjects had no clinical deposits in the cornea, demonstrating incomplete penetrance of the disorder in this family. Conclusions Clinical differences in corneal phenotypes within this CD family and with other pedigrees carrying the same TGFBI genetic defect could be explained by the age of clinical examination of individual patients and/or by the presence of genetic and/or environmental modifiers.