Abstract
Thyroid carcinoma is the most common malignancy of the endocrine system and its incidence is still growing. The majority of thyroid tumors occur in sporadic form, however, some are inherited in families.
The carcinomas can be divided into two groups according to the types of thyroid cells. Medullary thyroid carcinoma is derived from parafollicular C-cells. 20 - 25% of medullary thyroid carcinomas are inherited in multiple endocrine neoplasia type 2 syndromes.
Genetic causes are activated by germ-line mutations in the RET proto-oncogene, which are transmitted autosomal, dominantly. At present the routine genetic screening and presymptomatic treatment (i.e. prophylactic total thyreoidectomy) on the basis of genotype-phenotype correlation has already been developed.
The second group consists of carcinomas derived from follicular cells of thyroid that can be divided into differentiated (papillary and follicular) and nondifferentiated (anaplastic and poorly differentiated) ones. Also in this group 5-15% of carcinomas are cases of different familial syndromes (Gardner, Cowden, Werner syndromes and Carney complex) or only simple familial papillary thyroid carcinoma.
Although the genetic basis of inherited cancer syndromes are mostly known (APC, PTEN, PRKAR1α and WRN genes), the cause of nonsyndromic familial papillary thyroid carcinoma is still under investigation, several predisposition genetic loci are recognized.