Riboflavin 1 Transporter Deficiency: Novel SLC52A1 Variants and Expansion of the Phenotypic Spectrum

Riboflavin transporter 1 (RFVT1) deficiency is an ultrarare metabolic disorder due to autosomal dominant pathogenic variants in SLC52A1. The RFVT1 protein mainly expressed the placenta and intestine. To our knowledge, only five cases of from three families have been reported so far. While newborns infants with SLC52A1 showed a multiple acyl-CoA dehydrogenase deficiency-like presentation, individuals identified adulthood were usually clinically asymptomatic. We report two patients novel heterozygous variants. Patient presented at age 62 mild hyperammonemia following gastroenteritis. An acylcarnitine analysis dried blood spots was abnormal pattern, genetic confirmed variant, c.68C > A, p. Ser23Tyr. 2 recurrent seizures hypsarrhythmia 7 months. Metabolic investigations yielded unremarkable results. However, whole exome sequencing revealed start loss c.3G Met1Ile These expand clinical spectrum riboflavin demonstrate that symptomatic presentation possible.