The HLAB*18,BF*F1 in haplotype in type 1 diabetes.

We have investigated the properdin factor B (BF) locus as a possible marker for Type 1 diabetes. The frequencies of the four BF alleles were determined among 70 Type 1 diabetics with onset before age 18 years. The frequency of BF F1 among the diabetics was increased compared with 206 controls (15.7 vs 3.4%). The relative risk (RR) associated with BF F1 was 5.30. The suggestion that BF is most strongly associated with onset of diabetes under 10 years of age was not supported. HBLA 18 was increased (RR = 4.91) and B7 was decreased in frequency (RR = 0.41) among the 62 diabetics tested compared with 238 controls. An association was observed between HLAB 18 and BF F1 among the diabetics. A study of 12 families in which BF*F1 was segregating suggested that BF*F1 and HLAB*18 are components of a haplotype associated with Type 1 diabetes in this population and that both haplotypes of an affected parent may contribute to the development of Type 1 diabetes.