HLA-DRB1*04, -DRB1*1401, -DRB4, -DQA1*0104, -DQA1*03011, -DQB1*0302, and -DQB1*0502 alleles have been significantly increased in our patients group. Moreover, the haplotypes HLA-DRB1*04/-DQA1*03011/-DQB1*0302 and HLA-DRB1*1401/-DQA1*0104/-DQB1*0502 increased significantly in our patients. In contrast, the following alleles decreased significantly in our patients: HLA-DRB1*15, -DRB1*0301, -DRB1*07, -DRB1*11, -DRB5, -DQA1*0101, -DQA1*0103, -DQA1*201, -DQA1*05, -DQB1*0201, -DQB1*0301, -DQB1*06011, and -DQB1*0602. In addition, HLA-DRB1*15/-DQA1*0103/-DQB1*06011, HLA-DRB1*0301/-DQA1*05011/-DQB1*0201, HLA-DRB1*07/-DQA1*0201/-DQB1*0201, and HLA-DRB1*11/-DQA1*05/-DQB1*03011 decreased significantly in our patients. Genetic factors are involved in the occurrence of PV; HLA-DRB1*04 and -DRB1*1401 alleles and the related haplotypes are suggestive to be two major PV susceptibility factors in our population study.

IL-6 and TNF-alpha proinflammatory cytokine gene polymorphisms could change individual susceptibility to IBS and might have a role in pathophysiology of disease.

Chronic myelogenous leukaemia (CML) is a disorder of the haematopoietic stem cell that results in malignant expansion of myeloid cells with a cytogenetic abnormality, and translocation between chromosomes 9 and 22, known as the Philadelphia chromosome. It has been hypothesized that genetic factors other than histocompatibility disparity may play a role in predisposition to developing CML. In this regard, T helper types 1 and 2 (Th1 and Th2) cytokines and their gene polymorphism seem to be important. Overall expression and secretion of cytokines are dependent, at least in part, on genetic polymorphism (nucleotide variations) within the promoter region or other regulatory sequences of cytokine genes. The majority of polymorphisms described are single nucleotide polymorphism (SNPs). The objective of this study was to analyse the genetic profile of Th1 and Th2 cytokines in 30 Iranian patients with CML and 40 healthy subjects. In the patients and control subjects, the allelic and genotype frequencies were determined for the cytokine genes. All typing were performed with a polymerase chain reaction-sequence-specific primers (PCR-SSP) assay. Allele and genotype frequencies were calculated and compared with those of normal controls. The results showed that the most frequent genotypes in our patients were transforming growth factor (TGF)-beta TG/TG, interferon (IFN)-gamma AT, interleukin (IL)-4 CC at position -590, TT at position -33, and IL-10 ACC/ACC and ATA/ATA. In contrast, the genotypes TGF-beta CG/CG, IL-2 TT at position -330, IL-4 CT at position -590, CT at position -33, and IL-10 GCC/ACC were seen at much lower frequencies. The results suggest that production of TGF-beta in CML patients is higher and production of IL-4 and IL-10 is lower than in normal subjects.

Inflammation and mucosal immune system activation have an important role in irritable bowel syndrome (IBS), whereas genetic factors can control some immunological mediators. In this study, a number of polymorphic genes coding for T-helper 1, T-helper 2, and T-regulatory cytokines were genotyped in 71 patients with IBS, and the results were compared with controls. IL-4 CC genotype at position -590, IL-4 TT genotype at position -33, and IL-10 GA genotype at position -1082 were significantly overrepresented in the patients with IBS in comparison with controls (P < 0.001). The frequencies of the following haplotypes in the patient group were significantly higher than in the control group: IL-2 (-330, +160) GT haplotype (P = 0.002), IL-4 (-1098, -590, -33) TCC haplotype (P < 0.001), and TCT haplotype (P < 0.001). While production of cytokines could be affected by genetic polymorphisms within coding and promoter regions of cytokine genes, IL-4 and IL-10 gene polymorphisms could affect individual susceptibility to IBS.