Maternal vitamin deficiency mimicking multiple acyl-CoA dehydrogenase deficiency on newborn screening

BACKGROUND: In infancy multiple acyl-CoA dehydrogenase deficiency (MADD) is commonly a severe inherited metabolic disease caused by genetic defects in electron transfer flavoprotein (ETF) or ETF ubiquinone oxidoreductase. Both enzymes require flavin adenine dinucleotide (FAD) as a cofactor. Riboflavin (vitamin B(2)) is a precursor in the synthesis of FAD. MADD can be detected by newborn screening (NBS) based on elevation of multiple acylcarnitines. METHODS: We present the results of two children whose NBS results and subsequent confirmatory testing resulted in a suspected diagnosis of MADD. In parallel in both children vitamin B(12) deficiency was detected. RESULTS: Biochemical profiles normalized rapidly in both children under supplementation with riboflavin. After extensive work-up of both cases including molecular genetic studies there was no indication of MADD. Vitamin B(12) deficiency in both children was caused by maternal vitamin B(12) deficiency and was rapidly corrected by oral supplementation with vitamin B(12) or (partial) formula feeding. As both vitamin B(12) and riboflavin have similar food sources we postulate that in these cases positive NBS for MADD was caused by combined maternal vitamin B deficiencies. CONCLUSION: The differential diagnosis of maternally caused vitamin B deficiencies should be considered in children with abnormal NBS results for MADD, especially in the presence of normal molecular genetic analysis or in case of associated findings of other maternal vitamin B deficiencies like vitamin B(12) or folic acid deficiency.