Reduced-median haplotype network of ABCB1 haplotypes found with frequencies >5% in the set of 24 CEPH trios, as described in Table 2. Loci include IVS 6+139C>T, IVS 6+251A>G, 1236C>T, IVS 16+73G>A, 2677G>T,A, 3435C>T, IVS 26+1573T>C, and IVS 26+1684 of Table 1. Node size is proportional to haplotype frequency. Mutated positions are indicated by white dots. The ancestral haplotype was determined by resequencing of a chimpanzee sample (gray).