A real benefit of an extended neonatal screening

Methylenetetrahydrofolate Reductase (MTHFR) deficiency, is avery rare congenital defect of folate metabolism, inherited in an autosomal recessive pattern included in newbornscreening (NBS) programs in Italy. It is caused by mutations in the MTHFRgene and is characterized by elevatedplasma homocysteine and borderline-low or normal methionine levels, causing severe neurological signs, recurrentapnoea, microcephaly and convulsions, generally during the neonatal period. An early treatment may prevent theclinical manifestations with a positive impact on patient’s health. We report a new case of MTHFRdeficiency, identified during NBS that showed hypomethioninemia 4.6 μmol/L (r.i.6-20). The second level-test revealed hyperhomocysteinemia (106.7 μM, r.i. 5-15). The whole sequencing of theMTHFRgene showed two missense mutation: c.176G>C (p.Trp59Ser), reported as disease causing and the novelc.1769T>G (p.Leu590Arg), classified as likely pathogenetic. The baby was immediately treated with vitamin B12,folate and betaine; after 12 months of follow-up he has no signs or symptoms of the disease. In conclusion, this case report highlights the importance of NBS for inborn errors of metabolism and genetic analysis,that can prevent the establishment of a serious disorder of folate metabolism.