Epithelial recurrent erosion dystrophy (ERED) from the splice site altering COL17A1 variant c.3156C>T in families of Finnish‐Swedish ancestry

Abstract

PurposeTo describe four Finnish families with epithelial recurrent erosion dystrophy (ERED) caused by the pathogenic variant c.3156C>T in collagen type XVII alpha 1 chain gene (COL17A1).MethodsEleven affected and two unaffected individuals underwent clinical ophthalmological examination, anterior segment photography, and corneal topography. Two of them underwent phototherapeutic keratectomy (PTK). Genetic analysis included both next‐generation and Sanger sequencing. Specimens from the manual keratectomy of one patient were available for ophthalmic pathologic examination, including immunohistochemistry.ResultsThe common splice‐site altering synonymous variant c.3156C > T, p.(Gly1052=) in COL17A1 was confirmed in 15 individuals with ERED from the four families. Subepithelial corneal scarring grades varied and increased with age, leading to decreased best‐corrected visual acuity. PTK improved vision in 58‐ and 67‐year‐old individuals without reactivating the disease. The keratectomy specimens showed an uneven epithelium and a spectrum of basement membrane abnormalities, including breaks, fragmentation, multiplication and entrapment within the subepithelial scar, reflecting recurrent erosions. The stromal cells consisted of varying proportions of bland and activated fibroblasts and myofibroblasts, reflecting different ages of scars. The family with the largest number of known affected generations originated from Southern Sweden.ConclusionThe phenotype in the Finnish ERED families is consistent with earlier reports of the c.3156C > T variant, although the severity has varied between reports. The phenotype may be modulated by other genes. This study suggests a likely founder effect of the variant in both Finnish and Swedish populations due to their shared population histories. If vision is compromised, PTK can be considered especially in older patients.

IC3D Classification of Corneal Dystrophies—Edition 3

“…This evidence ideally includes examination of the cornea through a dilated pupil and examination of multiple generations of a family. [14][15][16] The Evolution of the EREDs Template After the discovery of ERED in 2015 from mutations in the COL17A1 gene, the logical question was whether FRCD, DS, and DH mapped to this same gene. Unfortunately, there are no publications regarding this information.…”