Islet cell and other organ-specific autoantibodies in healthy first-degree relatives to insulin-dependent

The presence of organ-specific autoantibodies including islet cell surface, cytoplasmic and cytotoxic as well as thyroid-gastric antibodies were determined in healthy, non-diabetic, first-degree relatives to 30 insulin-dependent diabetic (IDDM) children. Thirty healthy families without family-history of diabetes mellitus served as controls. The prevalence of organ-specific autoantibodies among the healthy members in the diabetic families was increased compared to the control families (p < 0.005). Islet cell cytoplasmic antibodies were only detected in diabetes families, since 23% (7/30) of the probands and 7% (2/31) of the siblings were positive and all others negative. Organ-specific autoantibodies were associated with HLA DR3 only in the diabetes families (p < 0.025) while autoantibody positive members in the control families were associated with HLA B7 (P < 0.01). This study suggests that childhood IDDM occurs in families with an increased prevalence of organ-specific autoantibodies.