Child Neurology: Five-Year Update on Siblings With Riboflavin Transporter Deficiency

Riboflavin transporter deficiency (RTD), previously referred to as Brown-Vialetto-Van Laere syndrome, is caused by pathogenic variants in the <i>SLC52A1</i>, <i>SLC52A2</i>, or <i>SLC52A3</i> genes, resulting in RTD types 1, 2, and 3, respectively. Researchers estimate an occurrence of approximately 1 in 1,000,000. There is only one case of type 1 described in medical literature. Type 2 is characterized by muscle weakness in the arms and neck, vision loss, hearing impairment, and sensory ataxia. In type 3, vocal cord paralysis is more common and muscle weakness is more generalized. In 2018, we described a case of a 6-year-old girl with RTD type 2 who made remarkable visual recovery after initiation of treatment with oral riboflavin and coenzyme Q10 supplementation. The patient's younger brother began the same treatment regimen after genetic testing confirmed that he carried the same genetic variant. In this report, we update the visual and neurologic status in these siblings 5 years after our initial report and 7.5 years after initiation of riboflavin treatment.