Metabolic screening in children: newborn screening for metabolic diseases past, present and future

Newborn screening began with the diagnosis of phenylketonuria using a simple test applicable to all newborn babies. Treatment could be given before the onset of brain damage with near normal outcomes. Methods became available to screen for and treat a variety of inborn errors of metabolism, but their application was patchy. Screening for hypothyroidism is now universal in the UK, and screening for cystic fibrosis and, more recently, haemoglobinopathies is being implemented nationally. Tandem mass spectrometry allows detection of more than 30 metabolic disorders using the neonatal screening blood spot. Considerable worldwide experience is now available and limited studies have shown favourable outcomes. Following a pilot study, the UK is to adopt tandem mass spectrometry screening for medium-chain acyl-CoA dehydrogenase deficiency. There is the potential to develop expanded newborn screening for aminoacidopathies, urea cycle disorders, organic acidaemias and fatty acid oxidation defects.