RÉSUMÉ
Aim Breast cancer was one of the most cancer occurred in women worldwide. Taq 1 polymorphism, a silent SNP,was thought to be genetic risk factor for breast cancer. This study was aimed to understand the relationshipbetween vitamin D receptor gene–Taq 1 (RS 731236) polymorphism and plasma vitamin D level among breastcancer patients in RSU H. Adam Malik Medan. Material and Methods Blood sample was collected from 53 newbreast cancer cases that had not received any chemotherapy. DNA isolation and gene amplification was doneusing PCR then followed with RFLP using Taq 1 restriction enzyme. The level of 25(OH)D was measured usingELISA. Result and Discussion Study results showed TT genotype was 92.5%, TC genotype was 7.5%, CC genotypewas 0 % using Hardy-Winberg Equilibrium (HWE) p=0.77, mean value of vitamin D level in study subject was28.16 ng/ml (CI 95%: 25.71-30.60). Fisher exact test analysis concluded that polymorphism of vitamin D receptorgene-Taq1 associated with plasma vitamin D group levels among breast cancer patients in H. Adam MalikHospital, Medan (p= 0.033) but there was no difference in mean plasma vitamin D levels between genotypegroups of Taq1 (p=0.141). Conclusion Vitamin D receptor gene-Taq1 polymorphism was associated with plasmavitamin D group level and but no significant differences in mean plasma vitamin D levels between genotypegroups of Taq1.