Abstract
PurposeSchnyder corneal dystrophy (SCD) is a rare inherited disease that leads to gradual vision loss by the deposition of lipids in the corneal stroma. The aim of this study is to report a novel pathogenic variant in the UBIAD1 gene and present clinical and molecular findings in Polish patients with SCD.MethodsIndividuals (n = 37) originating from four Polish SCD families were subjected for a complete ophthalmological check-up and genetic testing. Corneal changes were visualized by slit-lamp examination, anterior segment optical coherent tomography (AS-OCT), and in vivo confocal microscopy (IVCM).ResultsIn a proband with primarily mild SCD that progressed rapidly at the end of the fifth decade of life, a novel missense pathogenic variant in UBIAD1 (p.Thr120Arg) was identified. The other studied SCD family represents the second family reported worldwide with the UBIAD1 p.Asp112Asn variant. SCD in the remaining two families resulted from a frequently identified p.Asn102Ser pathogenic variant. All affected subjects presented a crystalline form of SCD. The severity of corneal changes was age-dependent, and their morphology and localization are described in detail.ConclusionThe novel p.Thr120Arg is the fourth SCD-causing variant lying within the FARM motif of the UBIAD1 protein, which underlines a high importance of this motif for SCD pathogenesis. The current study provides independent evidence for the pathogenic potential of UBIAD1 p.Asp112Asn and new information useful for clinicians.
Highlights
Schnyder corneal dystrophy (SCD; OMIM #121800) is a rare autosomal dominant disease classified within the group of stromal dystrophies (IC3D 2015, [1]) and caused by UBIAD1 pathogenic variants [2,3,4]
UBIAD1 gene pathogenic variants were found in a total of 18 subjects (11 females and 7 males aged 13–68 years; mean age 37.8 y/o)
In this study we have identified p.Thr120Arg, a novel heterozygous point alteration in the UBIAD1 gene causative of SCD
Summary
Schnyder corneal dystrophy (SCD; OMIM #121800) is a rare autosomal dominant disease classified within the group of stromal dystrophies (IC3D 2015, [1]) and caused by UBIAD1 pathogenic variants [2,3,4]. For every examined patient a corresponding identification number (#PatID format) together with a detected UBIAD1 allelic variant The most frequent pathogenic variants include p.Asn102Ser, p.Gly177Glu/Arg, and p.Leu121Phe. In 2016, p.Thr103Ile, the first de novo UBIAD1 gene pathogenic variant associated with SCD was identified [9]. All of the so far identified pathogenic variants leading to SCD encompass this domain [10]. The first loop is most frequently affected by SCD pathogenic variants which appear to disturb its hydrophilic property [14]
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