Although further studies are required to evaluate the clinical characteristics of hypothyroidism by measuring serum free thyroxine, T3, and TSH concentrations in the presence or the absence of TRH administration in patients with GATA2 mutations, it is significant to validate the possible association between GATA2 deficiency and the HPT axis using in vitro models. The gene discussed is GATA2; the disease is hyperinsulinemic hypoglycemia, familial, 4.