Extreme Myopia Caused by Alport Syndrome

Abstract

Importance: A novel mutation in the COL4A5 gene was found and the advantage of the aphakic formula for IOL calculations of patients with anterior lenticonus. Objective: To report the diagnosis and treatment of a special case of extreme myopia and a novel splicing mutation of Alport Syndrome. Methods: The proband underwent a complete ophthalmological examination, ultrasound biomicroscopy (UBM), Optical biometric measurement, fundus photography, optical coherence tomography (OCT), visual field testing, and hearing testing, and the patient underwent lens surgery. The expression of the alpha 5 chain of type IV collagen in the lens capsule was detected by immunofluorescence. Whole exome sequencing (WES) of the proband and Sanger validation of his parents were performed to screen for pathogenic mutations. Main outcome measures: Clinical characteristics of the proband, immunofluorescence, whole exome analysis, and Sanger validation. Results: The proband showed extreme binocular high myopia in both eyes, and the vision could not be improved. UBM showed that the central area of the lens of both eyes protruded forward. OCT showed retinal thinning in the temporal side of the macula in both eyes. The corresponding protein was not expressed in the lens capsule of the proband. WES revealed a novel mutation (c.4821+2T>C: p.?) in the COL4A5 gene. Sanger validation showed that the proband’s mother carried the mutation. There was no expression of the alpha 5 chain of type IV collagen in the lens capsule of the proband. In different formulas, the aphakic formula had the smallest error. Conclusion: This paper found a previously unreported mutation, and family analysis suggested that the mutation was inherited as an X-linked chromosome. During the diagnosis and treatment process, we found that the aphakic formula has a smaller predictive error.