COL1A2 GENE (ALPHA-2 GENE OF TYPE-I COLLAGEN) AT THE HAPLOTYPE LEVEL AS A NEW VALUABLE ANTHROPOGENETIC MARKER - A STUDY ON SARDINIANS

Sardinians, a population with many distinct anthropogenetic features, has been studied for the COL1A1 and COL1A2 genes at the DNA level for two purposes: to look for new RFLPs (restriction fragment length polym orphisms) and to study the distribution of three known COL1A2 RFLPs (E coRI, RsaI, MspI) at both the allele and the haplotype levels. None of the eleven enzyme-probe systems examined led to the discovery of a ne w polymorphism. The following frequency q was found for the less commo n allele of the three RFLPs: EcoRI, q(+) = 0. 178 +/- 0.03 1; RsaI, q( -) = 0.316 +/-0.038; MspI, q(-) = 0.046 +/- 0.017. EcoRI turned out to be the most discriminant of the three polymorphisms because the frequ ency of the (+) allele in Sardinians was about half that estimated for a large homogeneous white sample (0.18 +/- 0.03 vs. 0.30 +/- 0.01). S o far as the haplotype level is concerned, the sample is made up of tr iplets (parents and child). Therefore all the haplotype frequencies an d delta values (degrees of disequilibrium, D) were obtained by direct counting of the unambiguously identified haplotypes rather than being based on their maximum-likelihood estimates. This together with their analytical and detailed presentation makes these data comparable with future findings, provided that the two data sets are presented in a co mparable way. At this level the three RFLPs are efficient in distingui shing Sardinians from Calabrians (southern Italy) but not from the cen tral Italian population. The present results, besides adding a further discriminative criterion between Sardinians and Italians (and whites on the whole), identify the complex COL1A2 locus as a valuable anthrop ogenetic marker.