Settin et al. (2007) studied 50 children with chronic RHD (29 males and 21 females) from the Nile Delta region with rheumatic heart disease (RHD); in addition to 98 healthy unrelated controls. For all cases and controls, single nucleotide polymorphisms (SNPs) in the promoter regions of cytokine genes tumor necrosis factor (TNF)-alpha (-308) G/A, interleukin (IL)-10 (-1082) G/A, and IL-6 (-174) G/C as well as a variable number of tandem repeats (VNTRs) in intron 2 of the IL-1Ra gene were analyzed. All cases showed a significantly higher frequency of homozygous genotypes of IL-1Ra A1/A1. Cases with mitral valve disease showed a significantly higher frequency of homozygous IL-1Ra(VNTR) A1/A1. The same was observed for cases with severe valve lesions. On the other hand, all studied groups showed significantly lower frequency of heterozygous genotypes of IL-1Ra (VNTR) A1/A2.

Al-Moundhri et al. (2006) were the first to study the association of IL-1B and IL-1RN gene polymorphism with gastric cancer risk in an Omani population of 118 patients (mean age of 56.5 years, males 55.1%) diagnosed with gastric cancer in the period of 2002 to 2005. A group of 245 healthy individuals (mean age of 29.3 years, 56.9% males) from the same ethnic group and geographical region as the patients, were chosen as control. In the controls, the distribution of IL-B1 and IL-1RN alleles did not deviate much from that expected in the Hardy-Weinberg equilibrium. The frequencies of IL-1RN*2 allele were 15% in the Omani population in comparison to 26% in the Caucasian and 6% in the Asian populations. This study showed linkage disequilibrium between IL-1RN -2018 T-to-C at exon 2 and allele 2 of the VNTR polymorphism in the Omani patients and the controls. Increased risk of gastric cancer was associated with the carriage of IL-1RN*2 allele (OR of 2.2), and the heterozygous genotype of IL-1RN*2/L (OR of 2.6) and not the homozygous genotype of IL-1RN*2/*2 or any other studied polymorphism. On the other hand, increased gastric risk was associated with combined genotype of the IL-1RN *2/L with the homozygous wild IL-1B -31 TT, the combined genotype of IL-1RN *2 with IL-1B -31 *C allele carrier (twofold increase), and IL-1RN *2 in combination with homozygous wild IL-1B +3954 CC, or with IL-1B +3954 *T allele carrier (three fold increase). Almost 57% of the patients and 60% of the controls were positive for H. pylori, and the risk of gastric cancer was increased by 3.5 in those with IL-1RN*2, and by 5.4 times in those with IL-1RN 2/L if they acquired H. pylori infection. Upon classification of the gastric cancer according to histology as intestinal or non-intestinal, no effect on the gastric cancer risk for any of the genotypes was evident. Al-Moundhri et al. (2006) proved the ethnic differences in the effect of IL-1B polymorphism on gastric cancer carcinogenesis due to the absence of association between the IL-1B alleles (-31 and -511) and gastric cancer, but their results on the association between gastric cancer and IL-1RN polymorphism were consistent with previous reports. Later, Al-Moundhri et al. (2009) carried out a molecular study on the combined analysis of polymorphisms IL-1B/IL-1RN and GSTM1/G1 genes in gastric adenocarcinoma. A total of 107 control subjects and 107 gastric cancer patients were included in this study. Al-Moundhri et al. (2009) did not find any statistically significant associations between the GSTM1/G1 or IL-1B-31 genes and gastric cancer risk. However, they found a statistical association between the presence of the IL-1RN*2 allele and gastric cancer (odds ratio 2.2, 95% confidence interval=1.2-3.7, P=0.01). Combined analysis showed that a combination of carriers of IL-1RN*2 and the null GSTM1 genotype was associated with a statistically significant correlation with gastric cancer (odds ratio=3.6, 95% confidence interval=1.4-9.4, P=0.008). Al-Moundhri et al. (2009) suggested that the individual variation in both the cellular inflammatory modulator IL-1RN and the antioxidative property of GSTM1 may predispose individuals to an increased risk of gastric cancer.