Association of rs1544410 and rs7975232 Polymorphisms and Serum Vitamin D Levels with Psoriasis Susceptibility and Severity: A Case-Control Study in Egyptian Patients.

Background: Vitamin D is a regulatory factor for skin immune functions through vitamin D receptor, which is expressed on many immune cells. Vitamin D receptor is located on chromosome 12q 13.11 and has many single nucleotide polymorphisms. Some of them were hypothesized to be associated with psoriasis. Psoriasis is a genetic disease that is greatly affected by environmental factors. Methods: A total of 135 psoriasis patients and 114 healthy controls were recruited. Both had a measurement of serum vitamin D and two vitamin D receptor variants:, rs1544410: G > A (HGVS:NC_000012.12:g.47846052) and rs7975232: C > A (HGVS: NC_000012.12:g.47845054). We assessed the relationship between vitamin deficiency as well as the two gene polymorphisms with psoriasis susceptibility and severity. Results: Serum vitamin D levels were not significantly different between cases and controls. However, a significant association between vitamin D levels and severity was observed. We attributed this to our finding that rs7975232 was more significantly polymorphic among cases than controls, while rs1544410 polymorphism did not show a significant difference among the 2 groups. Conclusion: We did not find a significant difference in serum vitamin D levels between cases and controls. Yet, psoriasis severity was significantly associated with serum vitamin D levels. We attributed this to other findings that the vitamin D receptor rs7975232 gene is polymorphic in psoriasis patients. At the same time, rs1544410 was not significantly more polymorphic in psoriasis patients. Both genes' polymorphisms were associated with severe psoriasis.