Associations of Specific HLA-C Loci and Sociodemographic Factors with the Prevalence of Type I Psoriasis in Iraqi Patients

Psoriasis is an autoimmune inflammatory disease of human skin with the etiology being unknown and for which there is no cure. It is believed to be genetically and immunologically conditioned and has major negative impact on quality of life. This study aimed to determine the impact of inheritance of specific human leukocyte antigen-C loci and some sociodemographic factors on the susceptibility to early onset psoriasis (type I). The current study included psoriatic group involving 76 patients (type I) and a match of apparently healthy group comprising 87 persons as a control. A polymerase chain reaction based method (low resolution sequence specific primer) was used to detect C*06, C*07 and C*17 allele after informed consent. The study showed that the C*06 and C*07 allele were significantly associated with early onset psoriasis (p-value < 0.05), while C*17 showed no significant association. There was also a higher percentage of patients in urban districts (84.2%) than rural residents (15.8%). There was no significant association between smoking and type I psoriasis (p-value > 0.05). Both of C*06 and C*07 genotypes increased the risk of early onset psoriasis, while rural residency decreased the chance of getting type I psoriasis. Furthermore, the lack of association with smoking could not mitigate the effect of passive smoking.