MTHFR C677T polymorphism and thyroid cancer risk in Duhok, Kurdistan Region –Iraq
AbstractThyroid malignant tumors are common endocrine cancers that increased in incidence worldwide during the last decade. The disease recurrence is high, despite the death rate due to thyroid cancer is low. The etiology of thyroid cancer is still controversial, however, numerous genetic alterations in various thyroid tumors have been identified. Mutations in a gene encoding folic acid metabolizing enzyme, (Methyl Tetra Hydro Folate Reductase), named as (MTHFR), particularly the single nucleotide polymorphism MTHFR C677T has attracted our concern as a potential cause implicated in thyroid cancer. Formalin-fixed paraffin-embedded (FFPE) thyroid specimens with papillary carcinoma of 52 patients (18 male and 34 female) were donated kindly by Duhok histopathologic laboratories (Health Central laboratory). A group of 55 apparently healthy subjects were recruited (30 male and 25 female), after getting their formal consent. The DNA was isolated from both of the FFPE thyroid specimens of the patients and the venous blood samples of the healthy controls. The MTHFR polymorphism C677T was examined using the PCR-RFLP method using HinfI restriction enzyme. The thyroid cancer group consisted of 18 (34.6%) males and 34 (65.4 %) females, their age mean was 42.41 years. The cases were 3 (5.8%) anaplastic carcinoma, 43 (82.7%) papillary carcinoma, 4 (7.7%) follicular carcinoma and 2 (3.8%) medullary carcinoma. The control group consisted of 30 (54.5%) males and 25 (45.5%) females, their age mean was 43.6 years. The frequency of MTHFR C677T (CC, CT) heterozygous and TT homozygous variants among 52 thyroid cancer patients were 59.6%, 15.4% and 25% respectively, and the CT +TT combined variants were 40.4%. There was statistical significant difference between the MTHFR CC wild genotype and MTHFRC677T (CT,TT) variants. Among the 55 healthy controls, the MTHFR C677T genotype variants frequency of CC, CT heterozygous and TT homozygous were 85.%, 3.6% and 10.9% respectively, and the frequency of combined CT heterozygous +TT homozygous variants among the healthy controls was 14.5%. In conclusion, our results did not support a statistical association of the MTHFR C677T gene polymorphism variants with the risk of developing thyroid cancer neither with gender nor age adjustment.
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