Interleukin 1 Receptor Antagonist

Alternative Names

  • IL1RN
  • IL1RA
  • IL1 Inhibitor
  • Intracellular IL-1 Receptor Antagonist Type II

Associated Diseases

Type 2 Diabetes Mellitus
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OMIM Number

147679

NCBI Gene ID

3557

Uniprot ID

P18510

Length

34,655 bases

No. of Exons

13

No. of isoforms

4

Protein Name

Interleukin-1 receptor antagonist protein

Molecular Mass

20055 Da

Amino Acid Count

177

Genomic Location

chr2:113,099,359-113,134,013

Gene Map Locus
2q14.1

Description

The protein encoded by this gene is a member of the interleukin 1 cytokine family. This protein inhibits the activities of interleukin 1, alpha (IL1A) and interleukin 1, beta (IL1B), and modulates a variety of interleukin 1 related immune and inflammatory responses, particularly in the acute phase of infection and inflammation. This gene and five other closely related cytokine genes form a gene cluster spanning approximately 400 kb on chromosome 2. A polymorphism of this gene is reported to be associated with increased risk of osteoporotic fractures and gastric cancer. Several alternatively spliced transcript variants encoding distinct isoforms have been reported. [From RefSeq]

Molecular Genetics

The IL1RN gene spans a length of 16 Kb on the long arm of chromosome 2, within the same cluster that houses the other genes of the IL1 family. The IL1RN protein is made up of 177 amino acids, and has at least four isoforms. Three of these isoforms remain in the cytoplasm, whereas one is secreted outside the cell. A penta-allelic 86-bp variable tandem repeat, present in the gene's second intron has been specifically linked to certain disease states. Interestingly, a variation, T-2018C, in the promoter region of the gene, has been found to be in tight linkage equilibrium with allele 2 of the above mentioned VNTR (which has two repeats).

Epidemiology in the Arab World

View Map
Variant NameCountryGenomic LocationClinvar Clinical SignificanceCTGA Clinical Significance Condition(s)HGVS ExpressionsdbSNPClinvar
86 bp VNTR NM_173842.3:c.206-516ATCCTGGGGAAAGTGAGGGAAATATGGACATCACATGGAACAACATCCAGGAGACTCAGGCCTCTAGGAGTAACTGGGTAGTGTGC[2]LebanonNC_000002.12:g.113130529_113130614ATCCTGGGGAAAGTGAGGGAAATATGGACATCACATGGAACAACATCCAGGAGACTCAGGCCTCTAGGAGTAACTGGGTAGTGTGC[2]Likely PathogenicBenignFamilial Mediterranean FeverNG_021240.1:g.17637_17722ATCCTGGGGAAAGTGAGGGAAATATGGACATCACATGGAACAACATCCAGGAGACTCAGGCCTCTAGGAGTAACTGGGTAGTGTGC[2]; NM_173842.3:c.206-516ATCCTGGGGAAAGTGAGGGAAATATGGACATCACATGGAACAACATCCAGGAGACTCAGGCCTCTAGGAGTAACTGGGTAGTGTGC[2]223466314674
NM_000577.4:c.336T>CLebanonNC_000002.12:g.113132727T>CBenignBenignNG_021240.1:g.19835T>C; NM_000577.4:c.336T>C; NP_000568.1:p.Ser112=315952330827
NM_173841.3:c.215-516ATCCTGGGGAAAGTGAGGGAAATATGGACATCACATGGAACAACATCCAGGAGACTCAGGCCTCTAGGAGTAACTGGGTAGTGTGC[4]United Arab EmiratesNC_000002.12:g.113130529ATCCTGGGGAAAGTGAGGGAAATATGGACATCACATGGAACAACATCCAGGAGACTCAGGCCTCTAGGAGTAACTGGGTAGTGTGC[4]AssociationType 2 Diabetes MellitusNG_021240.1:g.17637ATCCTGGGGAAAGTGAGGGAAATATGGACATCACATGGAACAACATCCAGGAGACTCAGGCCTCTAGGAGTAACTGGGTAGTGTGC[4]; NM_173841.3:c.215-516ATCCTGGGGAAAGTGAGGGAAATATGGACATCACATGGAACAACATCCAGGAGACTCAGGCCTCTAGGAGTAACTGGGTAGTGTGC[4]2234663

Other Reports

Egypt

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.

Oman

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.

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