A study of ApaI and TaqI genotypes of the vitamin D receptor in Egyptian patients with psoriasis.

BACKGROUND: Vitamin D analogues have been found to be effective in treating the skin lesions of psoriasis. The therapy is thought to work through the vitamin D receptors, resulting in alteration of the proliferation/differentiation balance of the cells. Vitamin D also has an effect on T helper cells, which have a major role in the pathogenesis of psoriasis. There is controversy about the association of vitamin D receptor gene polymorphisms with psoriasis in different populations, and it is a factor that might influence the treatment of these patients. AIM: To study vitamin D receptor gene polymorphisms using two restriction enzymes in a group of Egyptian patients with psoriasis. METHODS: In total, 50 patients with psoriasis were examined using restriction fragment length polymorphism analysis to study ApaI and TaqI genotypes of the vitamin D receptor in a sample of Egyptian patients, and compared with 50 healthy control subjects. RESULTS: We did not find any significant difference in ApaI and TaqI vitamin D receptor gene polymorphisms between patients and controls. CONCLUSIONS: There is ethnic variability in vitamin D receptor gene polymorphisms. The lack of significant prevalence of the studied gene polymorphisms in our population suggests that their association with other functionally known gene polymorphism might have a role in the pathogenesis of psoriasis.

Use of the polymerase chain reaction mismatch technique to identify the HLA-DQw8 allele in patients with insulin-dependent diabetes mellitus.

The allelic forms of the HLA-DQB gene have been recognized as susceptibility markers of type 1 diabetes mellitus. One of these alleles, the DQw3.2 (DQw8), accounts for the well-documented association of the DQw3 locus with the disease. This report describes a method using the polymerase chain reaction mismatch technique to amplify the three different DQw3 allele sequences in 26 insulin-dependent diabetic patients. Primers were designed that differed only at one base at the growing end of their sequences. Using a common oligonucleotide primer located downstream in the first domain of the DQB gene and three other primers located at the other end of the sequence being amplified, it was possible to identify and distinguish the DQw8 allele from the other two closely related alleles (DQw7, DQw9). This method, which could be useful in excluding HLA-related susceptibility to diabetes mellitus, is rapid and nonisotopic, and indeed could be adapted to investigate any DNA sequence polymorphism.