Genetic marker for insulin-dependent diabetes mellitus.

A rare genetic type (Bf F1) of properdin factor B is found in 22.6% of patients with insulin-dependent diabetes mellitus but in only 1.9% of the general population, yielding a relative risk of 15.0. This indicates that a genetic locus for insulin-dependent diabetes mellitus is very close on chromosome 6 to Bf, and that Bf F1 is a marker for nearly 1 out of 4 insulin-dependent diabetic patients.