Riboflavin, a vital water-soluble vitamin, serves as a cofactor for numerous enzymes involved in cellular energy metabolism. Riboflavin deficiency can lead to diverse clinical manifestations and metabolic changes that mimic multiple acyl-CoA dehydrogenase deficiency (MADD). We report a case of a preterm female infant dependent on total parenteral nutrition (TPN) with insufficient riboflavin intake. The infant exhibited clinical and biochemical features resembling MADD; however, molecular analysis revealed no pathogenic or likely pathogenic variants associated with MADD or riboflavin transporter defects. Treatment with riboflavin, L-carnitine and multivitamin supplementation resulted in the resolution of clinical and biochemical abnormalities within 1 week. This case highlights that the transient MADD-like features were attributable to riboflavin deficiency induced by TPN.

Vitamin B2, riboflavin is essential for cellular function, as it participates in a diversity of redox reactions central to human metabolism, through its role as precursor for the cofactors flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are electron carriers. The electron transfer flavoprotein (ETF) and its dehydrogenase (ETFDH), uses FAD as cofactor. The ETF and ETFDH are forming the electron transport pathway for many mitochondrial flavoprotein dehydrogenases involved in fatty acid, amino acid and choline metabolism. A variation in either ETF or ETFDH causes multiple acyl-CoA dehydrogenation deficiency (MADD), but genetic variations in the riboflavin metabolism or transportation of riboflavin can also cause MADD. The most common variations are located in the riboflavin transporter 2 (RFVT2) and 3 (RFVT3), that are highly expressed in brain and intestinal tissues, respectively. Deficiency of riboflavin transporter 1 (RFVT1), encoded by the SLC52A1 gene, highly expressed in the placenta, has only been reported once. We here report a case of transient MADD, caused by a heterozygous intronic variation, c.1134+11G>A, in the SLC52A1 gene encoding RFVT1. This variation creates a binding site for the splice inhibitory hnRNP A1 protein and causes exon 4 skipping. Riboflavin deficiency and maternal malnutrition during pregnancy might have been the determining factor in the outcome of this case.