Medullary thyroid cancer in MEN2 pediatric/adolescent carriers of RET mutation: genotype/phenotype correlation and outcome in a retrospective series of 23 patients.

Background: Multiple endocrine neoplasia type 2 syndrome (MEN2) is a hereditary disease resulting from mutations of the rearranged during transfection (RET) protooncogene subclassified into MEN2A [medullary thyroid carcinoma (MTC), pheochromocytoma, and primary hyperparathyroidism] and MEN2B (MTC, pheochromocytoma, Marfanoid habitus, mucous neuromas, and intestinal ganglioneuromatosis). Prophylactic thyroidectomy is recommended in RET-mutated patients. The age at which it should be performed depends on the type and aggressiveness of the mutation.

A novel RET gene mutation in a patient with apparently sporadic pheochromocytoma.

Pheochromocytoma (Pheo) is a chromaffin tumor arising from the adrenal medulla. The recent discovery of new germline mutations in RET, SDHA, SDHB, SDHC, SDHD, VHL, NF1, TMEM127, MAX genes, increased the rate of genetic disease from 10% to 28% in patients with apparently sporadic tumor. RET germline mutations cause multiple endocrine neoplasia type 2 syndrome (MEN 2A) characterized by complete penetrance of medullary thyroid cancer (MTC), and lower prevalence of Pheo and hyperparathyroidism.

Lesch-Nyhan disease in a female with a clinically normal monozygotic twin.

Lesch-Nyhan disease (LND) is an inborn error of purine metabolism caused by defective activity of the enzyme hypoxanthine guanine phosphoribosyl transferase (HPRT, EC 2.4.2.