CRYPTIC DINUCLEOTIDE POLYMORPHISM IN THE 3' REGION OF THE FACTOR-IX GENE SHOWS SUBSTANTIAL VARIATION AMONG DIFFERENT POPULATIONS

Long tandem dinucleotide repeats composed of alternating purines and p yrimidines [RY(i)] are abundant and highly polymorphic. ''Simple'' RY( i) are predominately composed of one tandem repeat of a dinucleotide s equence. In contrast, ''cryptic'' RY(i) [cRY(i)] are composed of multi ple short dinucleotide repeats. Herein, we describe the racial distrib ution of alleles for a polymorphic cRY(i) in the factor IX gene. Allel e I is absent in Asians, whereas allele III is rare or absent in Cauca sians or blacks. A polymorphic cRY(i) analyzed previously shows even m ore dramatic variation among racial groups, hinting that a battery of cRY(i) might have utility in assessing the racial origin of a DNA samp le.