Genetics of paraoxonase.

Danish family material comprising 1664 unrelated individuals (parents) and 3169 children, as well as 699 grandparents of the same families, were examined for paraoxonase activity. A micro-autoanalyser method, comprising a primary testing in tris buffer at pH 7.5 and, in the case of primarily intermediate individuals, a secondary testing at pH 10, was applied. This gave a better discrimination than testing only at pH 7.5, because individuals around the low mode of the primary activity distribution had their pH optimum at pH 10, while the optimum of individuals around the high was at pH 8.5. By this combined testing all individuals could be unequivocally classified as 'low' or 'high', and the family material was compatible with the low phenotype representing homozygosity for an autosomal recessive gene with a frequency plow = 0.726. Out of 5532 individuals, 5 showed an almost complete lack of paraoxonase activity.