ARE THE SSTR ALLELES STABLE ENOUGH TO BE CONSIDERED MONAPHYLETIC AND HENCE RELIABLE ANTHROPOGENETIC MARKERS - LINKAGE DISEQUILIBRIUM STUDY ON THE (ACT)(N) COL1A2 SSTR

An extremely low production rate of a polymorphic allele (formally cal led the mutation rate)-a prerequisite for using the allele as a marker (particularly for anthropogenetic purposes where the alleles must be assumed to be monophyletic)-cannot be taken for granted for alleles of highly polymorphic VNTRs, but a low production rate can be used to id entify alleles produced by a single nucleotide substitution, This prop erty was indirectly tested for the (ACT)(n) COL1A2 (of type I collagen ) microsatellite SSTR (degree of heterozygosity H = 0.72) by searching for linkage disequilibria between the SSTR's four common alleles (n = 6, 8, 9, or 10) and three RFLPs of the same gene. A strong linkage di sequilibrium between at least three of the four SSTR alleles and two o f the three closely linked RFLPs has been demonstrated in a Sardinian population (Italy), a finding that suggests a low production rate of t hese alleles. Thus it seems that this highly polymorphic system and, b y a reasonable extrapolation, other VNTRs with a comparable degree of heterozygosity may be valuable anthropogenetic markers, at least in di stinguishing subgroups of a major ethnic group.