Frequency of inborn errors of metabolism, especially PKU, in some representative newborn screening centers around the world

Conclusions

It becomes quite clear, by comparing reliable data about frequencies of some inborn errors of metabolism in newborn populations scattered around the world, that the frequency of PKU is significantly different in different nations and races. For several of these differences the relationships and dissimilarities in the origin of present-day nations can be presumed as explanations. The examples of intra-Irish differences and those between Ashkenazi Jews and other European nations, demonstrate the possible effect of religious and social barriers. In Galactosemia by transferase deficiency, comparable observations can be made, although technical problems produce artefacts. At present there is no indication that Histidinemia has a different frequency in different parts of the world, but more data are needed. This is true also for Arginino-succinic-aciduria and Hartnup's disease where interesting differences in frequency have been observed but in too few screening centers.

The observation of significant differences in frequency of PKU and Galactosemia within such small countries as Ireland and Austria seems to indicate that comparison of frequencies in total newborn populations may only mask interesting differences by intranational equilibration. A politically defined modern nation need not necessarilly represent a genetic entity.

The study shows that the comparison of frequencies of inborn errors of metabolism is a valuable and inexpensive means of elucidating genetic relationships and dissimilarities between modern populations and of recognizing influences which define genetic compartments. This side effect of newborn screening programs could become much more fruitful if screening centers were spread more evenly arround the globe; the reliability of certain test procedures could be ensured and the number of generally sought—for disorders could be increased.