POLYMORPHISM AND SEQUENCE VARIATIONS OF THE HUMCD4 PENTAMERIC MICROSATELLITE IN AN ITALIAN POPULATION-SAMPLE

A sample of 265 subjects from central Italy was analyzed at the HumCD4 locus by polymerase-chain-reaction (PCR). Phenotypes were identified by comparison with a sequenced ladder, after high-resolution horizonta l polyacrylamide gel electrophoresis (PAGE) followed by silver stainin g. A set of representative alleles was sequenced by Tag-cycle-sequenci ng with dye terminator labeling and capillary gel electrophoresis stra tegies. Eight common alleles-5,6,7,8,9,10,11,12-and a rare larger 14, never before described in Caucasians, were found. Allele and genotype frequencies were similar to those described in former studies on Cauca sians, with a prevalency of alleles number 5, 6, 10. Sequence analysis showed that the polymorphism is due to a pentameric TTTTC basic motif , tandemly repeated, and that from allele number 10 onwards the fourth repeat presents a T to C translation (CTTTC). Instead, allele number 9 may exist in two forms, because 75% of alleles examined in this stud y presented the CTTTC motif at the fourth position, while the remainin g 25% had the basic repeat structure.