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 less than 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 less than 0.025) while autoantibody positive members in the control families were associated with HLA B7 (p less than 0.01). This study suggests that childhood IDDM occurs in families with an increased prevalence of organ-specific autoantibodies.