Background: Familial clustering in patients with permanent congenital hypothyroidism (CH) caused by thyroid dysgenesis (TD) has been reported in developed countries. There is no information on familial TD from developing countries.
Methods: A total of 312 first degree relatives belonging to 80 families of children with TD (group 1) and 40 families of age-matched normal children (group 2) were screened by thyroid ultrasonography, serum total thyroxine (T4) and thyroid stimulating hormone (TSH).
Results: Thyroid scintigraphy revealed agenesis in 78.7% of the patients, ectopic gland in 15%, and hypoplasia in 6.2%. The mean thyroid volumes were similar in parents and siblings of both groups. Eight (10.6%) mothers in group 1 were identified to have thyroid hypoplasia as compared with none in group 2 (P=0.03). Serum TSH was significantly higher in group 1 than in group 2 (P=0.004). Sixteen (7.8%) subjects (6 mothers, 5 fathers, and 5 siblings) in group 1 were found to have subclinical hypothyroidism as compared to none in group 2 (P<0.05). Four families were identified to have thyroid developmental anomalies and abnormal thyroid functions accounting for 5% of cases of familial TD in our cohort.
Conclusion: Thyroid developmental anomalies and thyroid function abnormalities are more frequent in first degree relatives of children with TD as compared with a control population. These findings suggest that possibly there is a genetic component of TD in Indian patients.
Keywords: congenital hypothyroidism; familial occurrence; first degree relatives; thyroid developmental anomalies; thyroid dysgenesis.