ETHNIC-DIFFERENCES IN ENZYME AND DNA POLYMORPHISMS OF HUMAN TISSUE-SPECIFIC ALKALINE-PHOSPHATASES

Enzyme and DNA polymorphisms and haplotypes of tissue-specific alkalin e phosphatase genes were studied in Finns, Saamis and Swedes. In place ntal alkaline phosphatase (PLAP) restriction fragment length polymorph isms (RFLPs), found after digestion with RsaI and PstI, no significant population differences were observed. The PstI RFLP of the germ cell alkaline phosphatase (GCAF) locus showed significant allele frequency variations between Finns and Swedes (p = 0.014) and between Saamis and Swedes (p = 1 x 10(-4)). Electrophoretic enzyme variants of PLAP were studied in Finns and Swedes. The PLAP variant 18 (D in older nomencla ture) was found at a polymorphic frequency in the Finnish sample. In a ll populations, strong linkage disequilibria were found between the RF LPs and between RFLPs and electrophoretic FLAP types. There was, howev er, one notable exception: between the RsaI RFLP of PLAP and the PstI RFLP of GCAP no linkage disequilibrium was found. Two new RFLPs were o bserved in the Finnish population sample, a RsaI mutant site in PLAP w ith a frequency of 0.02 and a KpnI mutant site outside and upstream of the PLAP gene with a frequency of 0.036. In accordance with findings in previous studies at the enzyme level, PLAP also appeared to be more polymorphic than GCAP and intestinal alkaline phosphatase at the DNA level.