Neonatal screening for inborn errors of metabolism in Switzerland

Abstract

Neonatal screening for inborn errors of metabolism in Switzerland began in 1965 at the Children’s Hospital in Zurich with screening for phenylketonuria (PKU) by assaying for phenylalanine on dried spots of blood. In 1967, this screening was also initiated at the Central Laboratory of the Swiss Red Cross in Berne. The program then rapidly expanded. Screening for maple syrup disease (MSUD) by the Guthrie leucine assay, for homocystinuria by the Guthrie methionine assay, and for galactosemia with first the galactose assay (modified Guthrie test according to Paigen) and then for galactose-l-phosphate uridyltransferase activity (Beutler and Baluda) were added. Over the years some modifications of the program occurred: in 1973, the enzyme fluorimetric test according to Wiedemann that measures galactose was introduced in Berne for galactosemia screening and in 1974 TSH screening by RIA for congenital hypothyroidism (CH) was begun. In 1986, the enzyme immunoassay (Delfia) became the method for CH screening. Histidinemia screening with the Guthrie histidine assay was conducted as a pilot study for one year but a low prevalence, inadequate treatment and the large number of untreated cases described with normal development prompted abandonment of this screening. In 198 1 methionine screening was also abandoned, since no case of homocystinuria was identified during the 16 year screening period. However, four cases of hypermethioninemia, among them patients with fructose intolerance, were discovered with this screening. Biotinidase screening was added 1986. In 1987 leucine screening was also stopped, due to the low prevalance of MSUD and the fact that screening specimens collected on day 4 might be too late for the very early newborn diagnosis required in this