Currently in Norway, we screen our newborn for two inherited metabolic disorders: Congenital hypothyroidism (CH) and Phenylketonuria (PKU).

There is now a proposal to expand the newborn screening program with an additional 19 inherited metabolic disorders:

• Maple syrup urine disease, MSUD
• Tyrosinemia type 1 and 2, TH1 and 2
• Homocystinuria, HCU
• Propionic acidaemia, PA
• Methylmalonyl- CoA mutase deficiency, MMA
• Multiple carboxylase deficiency, MCD/ BIOT
• Glutaryl-CoA dehydrogenase deficiency, GA1
• Hydroxymethylglutaryl-CoA lyase deficiency, HMG/ 3MGA
• 3-Methylcrotonyl-CoA carboxylase deficiency, 3-MCC
• 3-Ketothiolase deficiency, BKT
• Isovaleric acidaemia, IVA
• Medium-chain acyl-CoA dehydrogenase deficiency, MCAD
• Very long-chain acyl-CoA dehydrogenase deficiency, VLCAD
• Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency, LCHAD
• Multiple acyl-CoA dehydrogenase deficiency, GA2
• Carnitine transporter defect, CTD
• Carnitine palmitoyl transferase deficiency 1 and 2, CPT1 and 2
• Carnitine acylcarnitine translocase deficiency, CACT
• Congenial adrenal hyperplasia, CAH

These are rare diseases in Norway. The proposed disorders can cause serious morbidity including mortality if left untreated. The majority of these diseases can be treated by customized diets.

For 17 of the inherited metabolic disorders, we did not find summarized documentation describing the effect of newborn screening. We found systematic reviews regarding newborn screening for four of the inherited metabolic diseases; PKU, tyrosenemia, MCAD and CAH. Mortality was reported only for MCAD and CAH. The overall quality of the evidence is very low.

We do not know what effect to expect from newborn screening for inherited metabolic disorders.