Type 1 diabetes in offspring of parents with type 1 diabetes: the tip of an autoimmune iceberg?

The objective of the present study was to examine the prevalence of self-reported autoimmune diseases among offspring of type 1 fathers, type 1 diabetic mothers, and non-diabetic parents. Type 1 diabetic probands (n=265; mean age=42 yr), who were ascertained from the Children's Hospital of Pittsburgh Registry for 1950-1964, recently participated in the Familial Autoimmune and Diabetes Study. Non-diabetic probands (n=96), identified from voter registration lists and matched by age, race, median income, and duration of residence in the Pittsburgh area, were also enrolled. Offspring of type 1 diabetic probands were more likely to have a reported autoimmune disease (5.8% vs. 2.4%; p=0.067) than offspring of non-diabetic probands. Half the cases in the diabetic families were disorders other than type 1 diabetes, (e.g., rheumatoid arthritis, Crohn's disease, etc.). Stratification by parental gender revealed a marginally higher risk for type 1 diabetes among offspring of type 1 diabetic fathers compared to mothers (4.9% vs. 3.4%; p=0.38, respectively, through age 20 yr). However, the risk for other autoimmune disorders was statistically significantly increased among offspring of type 1 diabetic mothers (0% vs. 6.2%; p=0.02, respectively, through age 20 yr). These data suggest that offspring of type 1 diabetic parents may be at high risk of developing other autoimmune disorders during childhood, with pediatric diabetes representing the 'tip of an autoimmune iceberg'. The observed risk differences by parental gender, which have also been reported for other autoimmune disorders, warrant further investigation.