DISPERSION AND INSERTION POLYMORPHISM IN 2 SMALL SUBFAMILIES OF RECENTLY AMPLIFIED HUMAN ALU REPEATS

Newly isolated members of two recently propagated (young) Alu subfamil ies were examined for sequence diversity and insertion polymorphism in primate genomes. The smaller subfamily (termed HS-2) is comprised of approximately 5 to 25 members, while the larger (termed Sb2) includes approximately 125 to 600 members. Individual members of these Alu subf amilies share distinguishing sets of diagnostic mutations, are well-co nserved relative to each other, and have expanded in the human lineage . At least one member from each subfamily is known to be polymorphic i n humans. Three newly characterized HS-2 Alu family members as well as three Sb2 Alu repeats are monomorphic (fixed) in humans. The existenc e of a number of Alu subfamilies that have amplified in parallel withi n the human genome provides compelling evidence for the simultaneous a ctivity of multiple dispersed Alu source genes.