[Mass screening for histidinaemia:rationalization by selective thin layer chromatography. First results].

Since 1974 histidine and urocanic acid was estimated by thin layer chromatography (TLC) in all newborn infants in whom histidine blood levels had to be controlled because of an abnormal Guthrie-test. This entailed using dried blood spotted on filter paper to rationalize newborn screening for histidinaemia thus reducing the work involved. Three cases of histidinaemia were found amongst 66.064 newborn infants. In order to find these, 830 initialy suspicious Guthrie tests had to be checked. This is a control frequency of 1:80. 384 controls were necessitated by inhibition-zones, 482 by initialy elevated blood levels. Histidine and urocanic acid concentrations generally correlated well in the TLC; only 9 newborn infants showed results suggesting histidinaemia (elevated histidine and absent urocanic acid). All three histidinaemias discovered by Guthrie-test aswell were among them, so that in the end, with only 9 controls combining Guthrie-test and TLC, the same effectiveness could have been reached, as compared to 830, when using the Guthrie-test alone.