Autoimmune thyroid diseases (AITD), Graves disease (GD) and Hashimotos thyroiditis (HT) cluster in families. We investigated whether having a family history (FH) of AITD altered age of diagnosis. The cohort comprised 2296 GD (1920F,376M) and 361 HT (313F,48M) recruited according to standard diagnostic criteria. We compared age at diagnosis of GD or HT in those with or without a FH of overt hyper- or hypothyroidism (ascertained using a standardised questionnaire).
In males and females with GD, any FH of thyroid dysfunction reduced median age of diagnosis compared with no FH (females: 38.0 y [IQR 3048.25], n=900 vs 43 , n=1022, P<0.001; males: 41.0 [31.2553], n=148, vs 47.0 [34.2558], n=228, P=0.008). For HT, difference in age of diagnosis according to FH was females 39.0 [2950.8] vs 45.0  (P=0.002), males 40.0 [34.550] vs 54.0 [46.866], (P<0.001). For females with GD, a parental FH reduced age at diagnosis (parent with hyperthyroidism: 37.5 , parent with hypothyroidism: 35.0 , no FH 43.0 , P<0.001). For GD males and HT probands, only parental hypothyroidism (not hyperthyroidism) reduced age at diagnosis (male GD parent with hyperthyroidism: 44.0 [36.553.5], parent with hypothyroidism: 36.5 , no FH: 47.0 [34.558], P=0.002; female HT parent with hyperthyroidism: 42.0 [32.553.5], parent with hypothyroidism: 35.0 [2646.5], no FH: 45.0 , P<0.001; male HT parent with hyperthyroidism: 40.0 , parent with hypothyroidism: 42.0 [29.550], no FH: 54.0 [46.866]). For GD and HT probands, FH in mother or father exerted a similar influence. Diagnosis of thyroid dysfunction in siblings did not affect age at diagnosis of AITD in probands. The greater the number of relatives with thyroid dysfunction, the lower the age of diagnosis of AITD (GD females, 0 relatives: 43.0 , 1 relative: 39.0 , 2 relatives: 38.0 [30.549], 3 or more relatives: 35.0 [27.2645], P<0.001). FH of thyroid dysfunction (especially in parents) exerted a marked influence on age at diagnosis of both GD and HT, which could reflect ascertainment bias or genetic anticipation.
01 - 05 Apr 2006
European Society of Endocrinology