A Homozygous RET K666N Genotype With an MEN2A Phenotype.

Autor:	Jaber T; Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas, MD Anderson Cancer Center, Houston, Texas., Hyde SM; Department of Clinical Cancer Genetics, The University of Texas, MD Anderson Cancer Center, Houston, Texas., Cote GJ; Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas, MD Anderson Cancer Center, Houston, Texas., Grubbs EG; Department of Surgical Oncology, The University of Texas, MD Anderson Cancer Center, Houston, Texas., Giles WH; Department of Surgery, The University of Tennessee College of Medicine, Chattanooga, Tennessee., Stevens CA; Department of Pediatrics, Division of Medical Genetics, The University of Tennessee College of Medicine, Chattanooga, Tennessee., Dadu R; Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas, MD Anderson Cancer Center, Houston, Texas.
Jazyk:	angličtina
Zdroj:	The Journal of clinical endocrinology and metabolism [J Clin Endocrinol Metab] 2018 Apr 01; Vol. 103 (4), pp. 1269-1272.
DOI:	10.1210/jc.2017-02402
Abstrakt:	Context: Germline RET K666N mutation has been described as a pathogenic mutation with low disease penetrance for medullary thyroid cancer (MTC) without other features of multiple endocrine neoplasia type 2A. We describe a patient with homozygous RET K666N mutation with MTC and bilateral pheochromocytoma (PHEO). Case Description: A 59-year-old woman received a diagnosis of MTC after biopsy of two thyroid nodules. Coincident biochemical and radiologic testing was suspicious for bilateral PHEO, confirmed after bilateral adrenalectomy. There was no evidence of primary hyperparathyroidism (PHPT). She had a total thyroidectomy with neck dissection revealing bilateral MTC with lymph node metastases. Germline RET testing identified homozygous K666N mutations. Genetic testing of family members showed that both adult children harbor a heterozygous K666N mutation. Her 32-year-old son had an elevated calcitonin level and underwent thyroidectomy, which identified MTC. Her 30-year-old daughter had a normal calcitonin level. Prophylactic thyroidectomy showed C-cell hyperplasia only. Three of seven other family members were tested and found to carry the mutation. All had normal calcitonin levels, and none had biochemical evidence of PHEO or PHPT. Given the absence of PHEO in reported RET K666N families, our proband underwent genetic testing for causes of hereditary paragangliomas or PHEO. No additional mutations were identified. Conclusions: Here we report a case of a homozygous RET K666N mutation leading to coincident MTC and PHEO. Heterozygous presentations of RET K666N mutations have low penetrance for isolated MTC. We believe that the gene dosage associated with the homozygosity of this variant contributed to the occurrence of bilateral PHEO.
Databáze:	MEDLINE
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