Endocrine Abstracts (2017) 49 EP1348 | DOI: 10.1530/endoabs.49.EP1348

The role of vitamin D receptor gene FokI (rs2228570) polymorphism in the pathogenesis of thyroid associated orbitopathy

Adam Maciejewski1, Michal Kowalczyk2, Adam Czyzyk3, Teresa Gasinska4 & Katarzyna Lacka1

1Department of Endocrinology, Metabolism and Internal Medicine, Poznan University of Medical Sciences, Poznan, Poland; 2Department of Dermatology and Venereology, Poznan University of Medical Sciences, Poznan, Poland; 3Department of Gynecological Endocrinology, Poznan University of Medical Sciences, Poznan, Poland; 4Department of Internal Diseases and Oncologic Chemotherapy, Silesian Medical University, Katowice, Poland.

Introduction: Vitamin D, known mainly as a calcium-phosphorus homeostasis regulator, turned out to play also a significant role in the immune system modulation. Vitamin D deficiency has been reported in some autoimmune disorders. It is also suspected that polymorphisms of vitamin D-related genes comprise a risk factor for different autoimmune diseases. Therefore the aim of our study was to assess vitamin D receptor (VDR) gene FokI polymorphism in thyroid associated orbitopathy (TAO) in comparison to the controls among the Caucasian-Polish population.

Patients: The group studied consisted of 100 subjects diagnosed with TAO (mean age 53.8) and 142 healthy age and sex matched controls. TAO was diagnosed by clinical examination, TRAb assessment and orbit MRI or CT. TAO group was further divided into: A- orbitopathy from the onset of Grave’s disease, B- later development of TAO. In the control group both TAO and autoimmune thyroid diseases were excluded by clinical examination and thyroid ultrasound.

Methods: FokI polymorphism of the VDR was studied by PCR-RFLP analysis, randomly selected patients were additionally analyzed by direct sequencing. The statistical significance of differences between the allele and genotype frequencies in TAO vs controls, as well as in subgroups of TAO were evaluated by χ2 or Fisher’s exact test. A P-value of <0.05 was considered significant.

Results: Observed allele frequencies were in Hardy-Weinberg equilibrium. C allele and CC genotype were more frequent in TAO compared to the controls (59.50 vs 55.28% and 34.00 vs 31.69%, respectively), although differences were not statistically significant (P=0.36 and P=0.50). CC+CT genotypes (dominant inheritance model) were more frequent in the subgroup A compared to B (89.70% vs 75.00%), P=0.07.

Conclusions: There is no statistically significant difference in allele or genotypes distribution of VDR FokI polymorphisms between TAO and the control group among the Caucasian-Polish population.

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