SLC52A3-Related Riboflavin Transporter Deficiency in Two Saudi Siblings: A Case Report.

Brown-Vialetto-Van Laere syndrome (BVVLS), or riboflavin transporter deficiency (RTD), is a rare but treatable neurodegenerative disorder caused by pathogenic variants in the riboflavin transporter genes. We report the cases of two siblings with genetically confirmed SLC52A3-related RTD. The index case presented with progressive bulbar dysfunction and respiratory failure and was diagnosed after an initially challenging clinical course. During a subsequent pregnancy, prenatal genetic testing identified the same familial SLC52A3 variant, allowing maternal riboflavin supplementation during pregnancy and treatment of the affected sibling from birth. Following riboflavin therapy, the index case showed partial clinical improvement, while the younger sibling remained asymptomatic at one year of age. This report highlights the importance of early diagnosis and treatment of RTD and the potential benefit of starting therapy before the onset of symptoms.