The rs7041 and rs4588 polymorphisms found in the GC gene, encoding vitamin D-binding protein (DBP), have distinct biochemical phenotypes. The aim of this study was to investigate vitamin D parameters with these polymorphisms, in individuals with possible vitamin D deficiency. The most common (49% of the cohort) genotype in rs7041 was GT, especially among individuals with high levels of free 25(OH)D calculated but with low levels of bioavailable 25(OH)D, and in rs4588 it was AC in particular among the individuals with low levels of bioavailable 25(OH)D. The most common phenotypes were Gc1s/2 (35.3%) and Gc1s/1s (31.4%), and Gc1f/1f was rare (5.9%). The variations in free and bioavailable 25(OH)D levels among healthy Turkish individuals may be attributed to the variations in total 25(OH)D as well as GC gene polymorphisms. The Turkish population shares a similarity for allele frequencies of rs7041 with the European population and similarity for allele frequencies of rs4588 with Gujarati Indians, and this may also be important in relation to certain ethnic populations showing associations between vitamin D and COVID-19.

Objective: Vitamin D is known to have important effects on human health. The existence of a relationship between obesity and vitamin D levels, which have been shown to cause a number of health problems with various studies, is certain. In this study, the relationship between vitamin D levels and body mass indexes(BMI) of individuals was evaluated. The study is unique for being the only research on literature that carried out with university employees. Materials and methods: Blood samples, anthropometric measurement (BMI) was obtained from 87 volunteer working at Haliç University. The questionnaire form covering the basic questions applied by means of face-to-face method. Quantification of the analytes for 25-hydroxyvitamin-D was carried out using LC-MS/MS. The relationship between 25-hydroxyvitamin-D values and BMI was evaluated with Tukey HSD multiple comparison test. 95% confidence and 80% power sampling were applied to the predictions of a minimum0.50 connection coefficient between 2 quantitative variables.The necessity of 30 cases was determined by using the N = [(Zα+Zβ)/C]2 + 3formula.Considering the losses, the work will be carried out over 80 people. Results and Discussion: There’s significant difference between 25-hydroxyvitamin-D2 and 25-hydroxyvitamin-D3 and the BMI levels of the subjects(p:0.028<0.05-p:0.000<0.05). The average 25-hydroxyvitamin-D3 and 25-hydroxyvitamin-D2 levels of overweight participants were significantly higher than the mean levels of underweight participants’. No significant relationship was found between 25-hydroxyvitamin-D3 and 25-hydroxyvitamin-D2 levels and the time spent outdoors during summer and winter. Conclusion: To prevent vitamin D deficiency and insufficiency is to obtain some sensible sun exposure, ingest foods that contain vitamin D, and take supplement. Bangladesh Journal of Medical Science Vol.19(2) 2020 p.229-236