[Neonatal screening for metabolic diseases: need for efficacy studies]

Neonatal screening in the Netherlands was extended in 2007. Twelve of the 17 diseases screened for are metabolic disorders. Only 2 of the metabolic diseases part of the neonatal screening programme in the Dutch population had been studied prior to the introduction of neonatal screening, namely galactosaemia and medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. Short-chain acyl-CoA dehydrogenase (SCAD) deficiency, a metabolic disease not added to the screening, was extensively studied recently. The authors concluded that SCAD deficiency did not meet screening criteria. The efficacy of screening should be investigated, as the screening test and genetic differences in populations make screening unique for each population. Clinical and biochemical phenotype do not always correlate with genotype. Differences in the disease population and the screening population can make decisions with respect to treatment difficult, especially when many more patients are found than expected. Some of these patients might never have become ill and should thus not be treated. Further studies are needed to differentiate between these patients.