Diabetes, Vol 43, Issue 1 87-94, Copyright © 1994 by American Diabetes Association
High genetic risk for IDDM in the Pacific Northwest. First report from the Washington State Diabetes Prediction Study
RE Rowe, NJ Leech, GT Nepom and DK McCulloch
Virginia Mason Research Center, Seattle, Washington 98111.
A combination of immune, genetic, and metabolic markers potentially
implicated in the development of insulin-dependent diabetes mellitus (IDDM)
was studied in the general population. We screened 3,992 healthy
schoolchildren, 12-18 years of age with no family history of IDDM, for
islet cell antibodies (ICAs). Of the children, 69 (1.7%) were found to be
ICA positive (ICA+), of whom 7 (0.17%) also were positive for insulin
autoantibodies (IAAs). ICA+ children (group 1) were human leukocyte antigen
(HLA) typed at the DQ locus along with 123 matched (group 2) and 235 random
(group 3) control subjects (from the original cohort of 3,992). Of the ICA+
children, 28 underwent beta-cell function (beta-CF) studies. High-risk DQ
types were surprisingly prevalent in all groups with 35.8% of random
control subjects carrying DQB1*0302 and 8.9% carrying the highest risk HLA
type for IDDM, DQB1*0302/*0201. Those individuals with higher ICA titer
(> 19 Juvenile Diabetes Foundation units [JDF U]) had a significantly
higher prevalence of DQB1*0302 than those with lower titer ICA or normal
control subjects. Six of 7 individual positive for both ICA and IAA and
typed at the DQ locus were DQB1*0302/*0201 heterozygotes or DQB1*0302 or
DQB1*0201 homozygotes, representing three of the highest risk genotypes for
IDDM. No correlation was observed between ICA titer or DQ type and beta-CF
except that all those with beta-CF below the 5th percentile carried either
DQB1*0302 or DQB1*0201. Prospective follow-up is underway to determine if
any combination of DQ type and immune markers predicts decline in beta-CF
and the development of IDDM.