Brief report: resistance to thyrotropin caused by mutations in the thyrotropin-receptor gene

Article Abstract:

A mutation in the thyrotropin-receptor gene may be transmitted to children of parents with the mutation and cause high levels of the hormone thyrotropin. In one family case, both parents, unrelated and of different ethnic backgrounds, had a mutated thyrotropin-receptor gene. Both of these mutant genes were transmitted to each of the couple's three daughters, the probability of which was about 1.6%. The diagnosis was made at birth in two of the daughters. All three sisters had 20 times higher than normal thyrotropin levels in the blood to maintain normal thyroid hormone secretion, thus masking the underlying condition of hypothyroidism. Complete DNA sequencing of the thyrotropin-receptor gene in the daughters revealed that the mutation derived from the genes of both parents. The parents had slightly higher than normal blood thyrotropin levels, indicating that the mutant genes were recessive. The father's mutant thyrotropin receptor was almost completely inactive, and the mother's had one-tenth of the normal activity.

Thyroid diseases

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Brief report: congenital hyperthyroidism caused by a mutation in the thyrotropin-receptor gene

Article Abstract:

A mutation that activates the thyrotropin-receptor gene may be the cause of congenital nonautoimmune hyperthyroidism in a child. The diagnosis was made shortly after the child's premature birth, because of symptoms of a rapid heartbeat, rapid, shallow breathing, and an enlarged thyroid gland. The patient received drug therapy to control his hyperthyroidism, but the condition persisted even with drugs when he was eight years old. Part of the thyroid gland was removed at this time, but hyperthyroidism continued. Radioiodine therapy finally produced a normally functioning thyroid. The germ-line mutation, a type of mutation that is transmitted to offspring, caused an amino acid substitution that activated the thyrotropin-receptor gene. This receptor controls the function and growth of thyroid cells. The location of the mutation in this case may be a more readily mutated spot than are other receptor locations. Phenylalanine at position 631 may play an important role in maintaining the receptor in its inactive state.

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Familial gestational hyperthyroidism caused by a mutant thyrotropin receptor hypersensitive to human chorionic gonadotropin. (Brief Report)

Article Abstract:

A gene mutation in the receptor for thyrotropin can cause hyperthyroidism in some pregnant women. Thyrotropin is a hormone that stimulates the thyroid gland. During pregnancy, another hormone called human chorionic gonadotropin is produced. This hormone can also stimulate the thyroid gland especially if blood hormone levels are excessive. A woman with persistent hyperthyroidism during pregnancy was found to have a gene mutation in the thyrotropin receptor. The mutation made the receptor more sensitive to human chorionic gonadotropin but not to thyrotropin. Consequently, she developed hyperthyroidism even though her human chorionic gonadotropin level was normal.

Health aspects, Gene mutations, Gene mutation, Genetic aspects, Cell receptors, Chorionic gonadotropin, Chorionic gonadotropins

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