J Retin.  2024 May;9(1):81-88. 10.21561/jor.2024.9.1.81.

Retinal Dystrophy Associated with a Novel RP2 Exon1 Deletion with Simultaneous TGFBI Point Mutation in Two Male Siblings: Case Report

• Choi SU
• Lee BH
• Lee S
• Ju YS
• Lee JS
• Lee JY

• KMID: 2556470
• DOI: http://doi.org/10.21561/jor.2024.9.1.81

Abstract

Purpose
We report two cases of retinal dystrophy with high myopia associated with a novel retinitis pigmentosa 2 (RP2) exon1 deletion and a simultaneous transforming growth factor β-induced (TGFBI) point mutation.
Case summary
The patients were two male siblings previously diagnosed with retinitis pigmentosa. They had a maternal family history of granular corneal dystrophy, and both presented with high myopia of ≥ -7.00 diopters (D). On ophthalmologic imaging, they displayed identical symmetric diffuse retinal dystrophy with hyperpigmented bony spicules in both eyes. Optical coherence tomography revealed diffuse thinning of the neurosensory retina and disruption of the ellipsoid zone. Full-field electroretinography showed nearly flattened cone and rod responses. Although targeted next-generation sequencing did not reveal any mutations in either case, whole-exome sequencing confirmed the existence of a single heterozygous TGFBI point mutation (c.371G>A(p.(Arg124His))) in both patients. Subsequent whole genome sequencing (WGS) confirmed novel RP2 exon1 deletion (c.-37_c.102+581del (720bp)).
Conclusions
In this case of familial hereditary granular corneal dystrophy, there were difficulties diagnosing and interpreting the genetic test results because of the very rare RP2 deletion. Prior to WGS, it was thought that retinal dystrophy could be attributed to an atypical clinical feature associated with the TGFBI mutation and high myopia. Retinal specialists who diagnose and manage these patients are advised to compile plans that consider appropriate genetic testing and interpretation of the outcomes.

Keyword

Cornea; Dystrophy; Retina; RP2; TGFBI