Autoimmune thyroid diseases (AITD), such as Graves' disease (GD) and autoimmune thyroiditis (AT), cluster within families and within individuals and exhibit a strong female preponderance. The type 1 diabetes Warren Repository was established between 1989 and 1996 and contains 505 families of British white Caucasian origin. Each family consists of both parents and at least two siblings with type 1 diabetes. We have examined the clinical data collected to establish the frequency and gender distribution of other autoimmune diseases within the families and second-degree relatives. 71% of families within the repository had a positive family history of other autoimmune diseases besides type 1 diabetes, with 23% of these diseases being attributable to GD, AT or unspecified thyroid disease. In all cases of AITD within the repository females were affected more often than males regardless of diabetic status with several of these comparisons reaching statistical significance (GD p < 0.001;AT p <0.0001). This finding is in contrast to that seen with type 1 diabetes where siblings of both sexes are equally affected by disease (47.5% sisters, 52.5% brothers). It was noted, however, that the female preponderance to AITD was reduced in the Warren Repository when compared to that seen in an unselected population used in the Whickham study with the female: male ratio in the Whickham study being 28: 1 for AT and 13: 1 in GD compared with 6: 1 for AT and 3: 1 for GD in the Warren repository. In conclusion, in the presence of an equal gender distribution of type 1 diabetes within the siblings, the female preponderance to AITD, although preserved, is reduced. It is possible that type 1 diabetes susceptibility genes influence the development of the other autoimmune diseases, such as AITD, thus lowering the female preponderance. These findings indicate that the Warren Repository may have an important role in investigating why females are more frequently affected by autoimmune disease, particularly AITD.
08 - 11 Apr 2002
British Endocrine Societies