Thus, in these cases, both the lack of increased TSH secretion as in primary hypothyroidism and decreased TRH and TSH secretion, resulting in insufficient FT4 secretion (secondary hypothyroidism) due to the immaturity (a transient form) or disorders of the hypothalamus and pituitary gland (a permanent form), were observed (4–6). The gene discussed is TRH; the disease is hypothyroidism.