Two subtypes of BfF by isoelectrofocusing: differential linkage to other HLA markers.

By isoelectrofocusing in agarose, the properdin factor allotype BfF could be split into two subtypes: BfFa with one major cathodic band and BfFb with the same cathodic band but in addition a major anodic band. By scanning, BfFaFb heterozygotes were distinguished from BfFbFb homozygotes by the stronger intensity of the anodic band in the latter. The two subtypes were segregated perfectly with HLA in 40 families and showed different association patterns with HLA markers. BfFa seemed to be linked to B35 while BfFb showed a strong linkage with all the components of the following haplotype: HLA-A29, Cw-, B44, BfFb, C4A3B1, DR7. The frequency of BfFa among BfFS heterozygotes was 41% (46/113) and that of BfFb 59% (67/113).