The impact of familial predisposition on the development of Hashimoto's thyroiditis.

Objectives: Hashimoto's thyroiditis (HT) is a common autoimmune disease. Available data show that HT develops as a result of interaction between genetic susceptibility and environmental factors, but the exact pathogenesis of the disease is not yet fully understood. The aim of this investigation is to evaluate the potential relationship between family history of HT and the development of HT.Methods: Data regarding family history of all patients who were referred for a diagnostic evaluation of thyroid function for any reason between May 2014 and May 2018 was analyzed. Only first-degree relatives were considered significant, whereas the data of distant relatives was not collected.Results: A total of 39 patients with positive family history of HT were extracted (Hashimoto group). As a control group, 39 patients with negative family history of HT were randomly chosen from the same database for the final analysis. When analyzing cytological diagnoses, there were 17 patients with confirmed HT in the Hashimoto group, and 7 in the control group (p = 0.0262).Conclusion: To the best of our knowledge, this is the first study directly showing that there is genetic predisposition for the development of HT in patients with positive family history of the disease (43.59% of patients with positive family history developed HT themselves). Assessment of a patient's family history in detail should become a standard procedure when a patient with any thyroid disorder is referred for diagnostic evaluation.