GLOBAL PATTERNS OF LINKAGE DISEQUILIBRIUM AT THE CD4 LOCUS AND MODERNHUMAN ORIGINS

Haplotypes consisting of alleles at a short tandem repeat polymorphism (STRP) and an Alu deletion polymorphism at the CD4 locus on chromosom e 12 were analyzed in more than 1600 individuals sampled from 42 geogr aphically dispersed populations (13 African, 2 Middle Eastern, 7 Europ ean, 9 Asian, 3 Pacific, and 8 Amerindian). Sub-Saharan African popula tions had more haplotypes and exhibited more variability in frequencie s of haplotypes than the Northeast African or non-African populations. The Alu deletion was nearly always associated with a single STRP alle le in non-African and Northeast African populations but was associated with a wide range of STRP alleles in the sub-Saharan African populati ons. This global pattern of haplotype variation and linkage disequilib rium suggests a common and recent African origin for all non-African h uman populations.