Case of Resistance to Thyroid Hormones With a Relatively Rare Mutation in Thyroid Hormones Receptor

Abstract

Normal thyroid hormone level is essential to maintain the normal physiologic function of the human body. Disturbances of these hormone levels have variable clinical manifestations ranging from asymptomatic to severe illness. Resistance to thyroid hormone (RTH) is a syndrome characterized by reduced intracellular action of T3, the active thyroid hormone. It is a rare autosomal dominant condition and occurs mostly due to heterogeneous mutations in the thyroid hormone receptor. Other causes of RTH include thyroid hormone cell membrane transport defect and thyroid hormone metabolism defect. Affected individuals present with symptoms of both increased and decreased thyroid hormone action, depending on the tissue's predominant receptor isoform expression, the magnitude of hormonal resistance, and the effectiveness of compensatory mechanisms. Here, we share our experience in diagnosing a case of RTH confirmed with a genetic test and found to have sequence variant mutation that is not well described in the literature previously due to the absence of genetic conclusive evidence.

Keywords: hypothyroidism; thrb gene mutation; thyroid disorders; thyroid hormone receptor mutation; thyroid hormones resistance.