Screening of parents and siblings of patients with thyroid dysgenesis by thyroid function tests and ultrasound

To investigate the frequency of thyroid dysgenesis (TD) in first-degree relatives of TD cases.

244 first-degree relatives of 82 TD cases were screened by thyroid ultrasound (USG), T(4), fT(4) and TSH. USG was also performed in 220 unrelated, age- and sex-matched healthy controls to obtain normative data for thyroid volumes.

Specific diagnoses of indexes were 35 ectopia, 22 athyreosis, 14 severe hypoplasia, 8 hypoplasia, and 3 hemiagenesis/asymmetric hypoplasia. In 5 of 77 families (6.5%), there were 2 cases with known symptomatic TD. A total of 10 cases made familial symptomatic TD ratio 12% (10/82) in our cohort. Screening of 244 asymptomatic family members did not reveal new cases with overt hypothyroidism. However, low thyroid volume in 15 and slightly elevated TSH in 6 family members and both in 1 family member were detected (7.4% for low thyroid volume, 3.2% for high TSH). Thus, the ratio of affected (symptomatic and asymptomatic) family members among families of TD cases was found to be 8.7%.

12% of TD cases are familial in our cohort. Screening of asymptomatic family members of TD revealed an additional 7.4% mild hypoplasia and 3.2% hyperthyrotropinemia without overt hypothyroidism which points out the importance of genetic factors in pathogenesis.