When we considered reconstructed haplotypes composed of 3 SNPs (rs737866-rs4680-rs174696), we found significant haplotypic association with CIP in EA families, and in EA and AA unrelated populations. Different haplotype frequencies in these two populations could explain the distinct association results. However, the A-A-T haplotype associated across EA families and the AA-case-control sample. Our EA family and EA and AA unrelated groups in this study contain variable proportions of affected individuals (53% and 52% in the EA and AA families, respectively, and 68% and 70% in the EA and AA unrelated populations, respectively). Occult population stratification is another possible concern in the unrelated samples. Nonetheless, the sample sizes are reasonably large, providing good statistical power, and the findings are generally consistent across samples and population groups. Additional replication is, however, desirable.
