Analysis of RET gene point mutation in a family with familial medullary thyroid cancer

Abstract

Objectives: Hereditary medullary thyroid cancer is presented as part of MEN 2A or MEN 2B, but can also be inherited alone, which is called familial medullary thyroid cancer(FMTC). Author sought to detect point mutation of RET proto-oncogene by using molecular genetic method on the family line of FMTC. Methods: DNA was extracted from the peripheral blood leukocyte of 6 medullary thyroid cancer patients (5 assumed sporadic and 1 assumed FMTC). After PCR amplification of exon 10, 11, 13, 14, 15, 16, point mutation of RET proto-oncogene was investigated using DNA sequence analyzer. When point mutation was identified in index patient of FMTC, same genetic study was conducted in their family Results: We identified point mutation of TGC(Cys)¡æCGC(Arg) at codon 618 of RET proto-oncogene exon 10 in 1 assumed FMTC patient. The same point mutation was detected in 4 of the 9 family members. Among them, index patient and her mother had biochemical and clinical symptoms and underwent total thyroidectomy and neck dissection. Operations are scheduled for remaining members with point mutation later on. Conclusion: Genetic analysis of RET proto-oncogene will overcome the limitations of classic calcitonin stimulation test and make the earlier diagnosis and treatment of FMTC be possible.