Diabetes, Vol 40, Issue 6 709-714, Copyright © 1991 by American Diabetes Association
Specific association of HLA-DR4 with increased prevalence and level of insulin autoantibodies in first-degree relatives of patients with type I diabetes
R Ziegler, CA Alper, ZL Awdeh, L Castano, SJ Brink, JS Soeldner, RA Jackson and GS Eisenbarth
Joslin Diabetes Center, Boston, MA 02215.
First-degree relatives of patients with insulin-dependent (type I) diabetes
(n = 264 from 106 families) were evaluated with HLA typing and
determination of competitive insulin autoantibodies (CIAAs) and islet cell
autoantibodies (ICAs). The levels of CIAAs in 30 relatives exceeded our
upper limit of normal (greater than or equal to 39 nU/ml), and 30 had
high-titer ICAs (greater than or equal to 40 Juvenile Diabetes Foundation
units [JDF U]). Eleven of the HLA-typed relatives developed diabetes during
follow-up. Twenty-three percent (28 of 123) of the relatives with at least
one HLA-DR4 allele were CIAA+ (CIAA greater than or equal to 39 nU/ml)
versus 4% (6 of 141) among DR4- relatives (P less than 0.0001). Twenty-one
of 22 of the highest CIAA values were all in the DR4+ group (DR4+ vs. DR4-,
P = 0.003, Wilcoxon's rank-sum test). HLA-DR3 did not correlate with the
level of CIAAs, and neither DR3 nor DR4 correlated with titer of ICAs
measured in JDF U. We conclude that, in first-degree relatives of patients
with type I diabetes, there is a striking association with HLA-DR4 in both
the prevalence of relatives exceeding the normal CIAA range and in the
level of CIAAs. These data suggest that a gene on HLA-DR4 haplotypes
contributes to the level of anti-insulin autoimmunity, and we hypothesize
that DR4-associated diabetes susceptibility, distinct from DR3-associated
susceptibility, may be secondary to this influence.