Best vitelliform macular dystrophy caused by a BEST1 p.(Ser246Asn) variant coexisting with diabetic retinopathy

To report a 42 year-old male patient with Best vitelliform macular dystrophy (BVMD) complicated by diabetic retinopathy, who harbored a missense variant in the BEST1 gene.

Comprehensive ophthalmological examinations, including full-field electroretinography (ERG) and electrooculography (EOG), were performed. Whole exome sequencing (WES) was conducted to identify potential disease-causing variant(s), and Sanger sequencing was used for confirmation.

Fundus photography and fluorescein angiography revealed macular degeneration and non-proliferative diabetic retinopathy with macular leakage. Although the light peak/dark trough (Arden) ratio on EOG was relatively preserved, a reduced light rise and attenuated dark trough amplitudes were observed. ERG demonstrated normal rod and cone system function. Based on optical coherence tomography findings, the BVMD stage was classified as a stage between the Vitelliruptive and Atrophic stages in the right eye, and as the Pseudohypopyon stage in the left eye. WES identified a previously unreported BEST1 variant, c.737G > A: p.(Ser246Asn) heterozygously, confirmed by Sanger sequencing.

This case emphasizes the importance of EOG assessment and genetic analysis in establishing an accurate diagnosis of BVMD, particularly in patients with coexisting conditions such as diabetic retinopathy.