Conserved worldwide linkage disequilibrium in the human factor XI gene

We have identified, in four diverse human populations, five common single-n ucleotide polymorphisms (SNPs) in the coding region of the gene for the blo od coagulation protease factor XI. Each SNP has an allele frequency >5% in at least one population. Three of the SNPs (C472T, A844G, and T1234C), spre ad out over approximately 10 kb of genomic DNA, are in marked linkage diseq uilibrium (LD) with one another (P < 10(-4)). Interestingly, haplotypes ass ociated with the linked SNPs are conserved across all populations studied, despite significantly different allele frequencies between populations. The presence of such common, widely dispersed haplotypes could complicate the interpretation of LD studies and emphasizes the need for a better understan ding of general patterns of LD to facilitate identification of genes for co mmon disorders. (C) 2000 Academic Press.