Gene-expression profiles in human nasal polyp tissues and identification of genetic susceptibility in aspirin-intolerant asthma

Background Aspirin‐intolerant asthma (AIA) is a subtype of asthma induced by non‐steroidal anti‐inflammatory drugs and characterized by an aggressive mucosal inflammation of the lower airway (asthma) and the upper airways (rhinitis and nasal polyp). The lower airway lesion and the nasal polyp in AIA are postulated to have common pathogenic features involving aspirin sensitivity that would be reflected in the gene expression profile of AIA polyps. Objective This study was conducted to clarify the pathogenesis of AIA using gene expression analysis in nasal polyps, and identify genetic susceptibilities underlying AIA in a case–control association study. Methods Global gene expression of nasal polyps from nine AIA patients was examined using microarray technology in comparison with nasal polyps from five eosinophilic sinusitis (ES) patients, a related disease lacking aspirin sensitivity. Based on the AIA‐specific gene expression profile of nasal polyp, candidate genes for AIA susceptibility were selected and screened by a case–control design of 219 AIA patients, 374 non‐asthmatic control (CTR), and 282 aspirin‐tolerant asthmatic (ATA) subjects. Results One hundred and forty‐three elevated and three decreased genes were identified as AIA‐specific genes that were enriched in immune response according to Gene Ontology analysis. In addition, a k‐means‐based algorithm was applied to cluster the genes, and a subclass characteristic of AIA comprising 18 genes that were also enriched in immune response was identified. By examining the allelic associations of single nucleotide polymorphisms (SNPs) of AIA candidate genes relevant to an immune response with AIA, two SNPs, one each of INDO and IL1R2, showed significant associations with AIA (P=0.011 and 0.026 after Bonferroni's correction, respectively, in AIA vs. CTR). In AIA–ATA association analysis, modest associations of the two SNPs with AIA were observed. Conclusion These results indicate that INDO and IL1R2, which were identified from gene expression analyses of nasal polyps in AIA, represent susceptibility genes for AIA.     

Association of Single Nucleotide Polymorphisms in the IL27 Gene with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is one of the autoimmune diseases, where different polymorphisms in cytokine genes play a pathogenic role. Interleukin 27 (IL‐27) is a novel pro‐/anti‐inflammatory cytokine, an excellent candidate for chronic inflammatory disease studies. The aim of the study was to identify polymorphisms in the IL‐27 gene and their possible association with susceptibility to and severity of RA. Two hundred and seventy‐four patients with RA and of 295 healthy individuals were examined for ?924A/G and 4730T/C IL27 gene polymorphisms using PCR‐RFLP method and TaqMan SNP genotyping assay, respectively. Haplotype frequencies of IL‐27 polymorphisms were estimated using SHEsis platform. Frequencies of the ?924GG genotype and the ?924G allele were statistically higher in RA patients comparing with the healthy control group (P = 0.008 and P = 0.004, respectively). Overall, strong LD was observed between the IL27 gene ?924A/G and 4730 T/C polymorphisms (D′ = 0.613, r2 = 0.199). From four possible haplotypes, frequencies of two (CA and CG) showed significant differences between both examined groups (respectively: P < 0.001 and P = 0.001062). The genotype–phenotype analysis showed significant association between the IL‐27 4730 T/C polymorphism and HAQ score and means value of the ESR, additionally they revealed that individuals with the polymorphic allele ?924G had more advanced disease than wild‐type allele carriers. Present findings indicated that IL27 ?924A/G polymorphism may be involved in susceptibility to RA in the Polish population.     

Evaluating association and transmission of eight inflammatory genes with Viliuisk encephalomyelitis susceptibility

Since the discovery of Viliuisk encephalomyelitis (VE) in 1887, scientists have tried to understand the natural history and aetiology of this endemic neurological disorder among the native Sakha population of Central Siberia. Familial aggregation and segregation analysis suggested a genetic influence on VE incidence. However, recent studies have implicated an unknown virus, possibly from the alpha herpesvirus family, as a possible cause for this disease. As VE is a neurological disease characterized by the inflammatory reactions systematically observed in the spinocerebellar fluid and in the brain tissue of deceased patients, we examined 17 single nucleotide polymorphisms (SNPs) across seven inflammation‐related candidate gene regions, including chemokine receptors type 2 and 5 (CCR2/CCR5), interferon‐γ (IFN‐γ), interleukin‐4 (IL‐4), IL‐6, IL‐10, stromal cell‐derived factor (SDF) and chemokine regulated upon activation, normal T‐cell expressed and presumably secreted (RANTES). Our main objective was to analyse the degree of genetic association between VE and candidate genes that have been previously implicated in other inflammatory diseases. Samples were collected from 83 affected families comprising 88 verified VE cases, 156 family members, and an additional 69 unrelated, unaffected inhabitants of the same geographical area. This collection included substantially all of the cases that are currently on the VE Registry. The experimental design included both case–control and transmission/disequilibrium test (TDT)‐based familial association analyses. None of 17 SNPs analysed was significantly associated with VE occurrence. Exclusion of these eight genes based on the lack of association has important implications for identifying the disease agent, as well as prescribing therapy and understanding Viliuisk encephalomyelitis.     

Polymorphisms in TDG and MGMT Genes – Epidemiological and Functional Study in Lung Cancer Patients from Poland

Functional genetic polymorphisms of DNA repair genes are good candidates for cancer susceptibility markers. We studied two genes coding for proteins removing small DNA adducts by direct repair (MGMT), or mispaired DNA bases by base excision repair (TDG). The non‐silent polymorphisms of MGMT (84:Phe, 143:Val, 178:Arg) and TDG (199:Ser, 367:Met), and the functional MGMT enhancer polymorphism, did not show any statistically significant association with lung cancer risk in our case‐control analysis, but due to the relatively small number of individuals, strong conclusions on cancer risk association or lack thereof cannot be made. Sequencing of the TDG cDNA has not revealed any novel polymorphism, but did find an alternatively spliced mRNA missing exon 2. Our search for polymorphisms within the promoter‐enhancer region of MGMT revealed three novel sequence variants. The functional significance of the previously published MGMT enhancer polymorphism (1099C‐>T) was assessed. The less frequent sequence variant of the enhancer was associated with a modest (16–64%), but statistically significant, increase of MGMT promoter‐enhancer activity in the studied cell lines. This work points to the importance of studying the expression‐regulating elements of genes, as they may contain functional polymorphisms with the potential for modulating risk of various diseases, including cancer.     

Linkage Disequilibrium Pattern in Asthma Candidate Genes from 5q31‐q33 in the Singapore Chinese Population

Studies have shown linkage between microsatellite markers from the chromosome 5q31‐q33 region with asthma, atopy and total IgE levels in the Singapore Chinese population. However, subsequent case‐control studies failed to show association between the polymorphisms in the candidate genes from this region and asthma or related phenotypes. In this study, we investigated 20 asthma candidate genes from this region for all possible informative polymorphisms within our population, linkage disequilibrium (LD) structure and tagging SNP transferability from HapMap populations. We re‐sequenced these genes and identified 267 polymorphisms including 26 insertion‐deletions, four microsatellite markers and 237 single nucleotide polymorphisms. The region contained 17 distinct LD blocks with the largest within the serine peptidase inhibitor kazal type 5 (SPINK5) gene spanning 23 kb. Of the 267 polymorphisms identified, 40% are represented in HapMap Han Chinese from Beijing and 29% in Han Chinese from Denver. 72% of the polymorphisms can be represented by tagged SNPs from the HapMap Beijing Han Chinese population and are highly correlated in terms of minor allele frequencies and LD structure. Our data suggest that although the HapMap Han Chinese population from Beijing is very similar to the Singapore Chinese population, this similarity is insufficient to account for up to 28% of the polymorphisms in the local population.     

Region 1p13.2 including the RSBN1, PTPN22, AP4B1 and long non‐coding RNA genes does not bear risk factors for endemic pemphigus foliaceus (fogo selvagem)

Pemphigus foliaceus (PF) is an autoimmune skin disease characterized by autoantibodies directed mainly against desmoglein‐1. The purpose of this study was to determine whether differential susceptibility to endemic PF in Brazil (fogo selvagem) is associated with polymorphisms at the cytogenetic location 1p13.2. Four single nucleotide polymorphisms that together tag 28 SNPs on a segment of approximately 312,000 bp encompassing the protein‐coding genes MAGI3, PHTF1, RSBN1, PTPN22, BCL2L15, AP4B1, DCLRE1B, the pseudogenes MTND5P20, RPS2P14 (AL133517.1) and the long non‐coding RNA genes AL137856.1, and AP4B1‐AS1 were used as markers for association analysis in a case–control study. Allele, genotype and haplotype frequencies of rs33996649, rs2476601, rs3789604 and rs3195954 were compared between patient and control samples. No significant association was found. Lack of association with rs2476601 of the PTPN22 gene agrees with previous results for pemphigus vulgaris and the Tunisian form of endemic pemphigus foliaceus. The other three SNPs had never been analysed before in any form of pemphigus. We conclude that variants in structural and regulatory sites of region 1p13.2 are not susceptibility factors for fogo selvagem. We suggest careful investigation of this genomic region in diseases that had been previously associated with PTPN22, since there are several other genes relevant for immune‐mediated diseases located in 1p13.2.     

Genetic variants in rheumatic fever and rheumatic heart disease

Genetic association studies in rheumatic heart disease (RHD) have the potential to contribute toward our understanding of the pathogenetic mechanism, and may shed light on controversies about RHD etiology. Furthermore, genetic association studies may uncover biomarkers that can be used to identify susceptible individuals, and contribute toward developing vaccine and novel therapeutic targets. Genetic predisposition to rheumatic fever and RHD has been hypothesized by findings from familial studies and observed associations between genes located in the human leukocyte antigens on chromosome 6p21.3 and elsewhere in the genome. We sought to summarize, from published Genetic association studies in RHD, evidence on genetic variants implicated in RHD susceptibility. Using HuGENet? systematic review methods, we evaluated 66 studies reporting on 42 genes. Existing meta‐analyses of candidate gene studies suggest that TGF‐β1 [rs1800469], and IL‐1β [rs2853550] single nucleotide polymorphisms (SNPs) contribute to susceptibility to RHD, whereas the TNF‐α [rs1800629 and rs361525], TGF‐β1 [rs1800470 and rs4803457], IL‐6 [rs1800795], IL‐10 [rs1800896] were not associated with RHD. However, candidate gene studies in RF/RHD are relatively small, thus lacking statistical power to identify reliable and reproducible findings, emphasizing the need for large‐scale multicenter studies with different populations.     

Association between GOLGB1 tag‐polymorphisms and nonsyndromic cleft palate only in the Brazilian population

Nonsyndromic oral clefts are common congenital birth defects that exhibit variable prevalence around the world, often influenced by population‐dependent genetic predisposition. Few studies have been performed with nonsyndromic cleft palate only (NSCPO), limiting the knowledge of the genetic risk factors related to this type of oral cleft. Genetic variants in golgin subfamily B member 1 (GOLGB1), a gene that is essential for normal murine palatogenesis, were analyzed in this study to establish its potential association with NSCPO risk in the Brazilian population. Five tag‐single nucleotide polymorphisms (SNPs) of GOLGB1 (rs1169, rs7153, rs9968051, rs9819530, and rs6794341), which capture the majority of alleles spanning within gene, were genotyped in a case–control study with 270 patients with NSCPO and 284 unrelated healthy controls. The samples were also genotyped for 40 biallelic polymorphic markers to characterize the genetic ancestry. After adjustment for co‐variants, the GOLGB1 tag‐SNPs and the haplotypes formed by those SNPs were not significantly associated with NSCPO in this Brazilian case–control cohort. Our results suggest that common polymorphisms of GOLGB1 are not associated NSCPO susceptibility in the Brazilian population.     

Multilocus analysis reveals three candidate genes for Chinese migraine susceptibility

Several genome‐wide association studies (GWASs) in Caucasian populations have identified 12 loci that are significantly associated with migraine. More evidence suggests that serotonin receptors are also involved in migraine pathophysiology. In the present study, a case–control study was conducted in a cohort of 581 migraine cases and 533 ethnically matched controls among a Chinese population. Eighteen polymorphisms from serotonin receptors and GWASs were selected, and genotyping was performed using a Sequenom MALDI‐TOF mass spectrometry iPLEX platform. The genotypic and allelic distributions of MEF2D rs2274316 and ASTN2 rs6478241 were significantly different between migraine patients and controls. Univariate and multivariate analysis revealed significant associations of polymorphisms in the MEF2D and ASTN2 genes with migraine susceptibility. MEF2D, PRDM16 and ASTN2 were also found to be associated with migraine without aura (MO) and migraine with family history. And, MEF2D and ASTN2 also served as genetic risk factors for the migraine without family history. The generalized multifactor dimensionality reduction analysis identified that MEF2D and HTR2E constituted the two‐factor interaction model. Our study suggests that the MEF2D, PRDM16 and ASTN2 genes from GWAS are associated with migraine susceptibility, especially MO, among Chinese patients. It appears that there is no association with serotonin receptor related genes.     

Identification of sequence polymorphisms of the COMP (cartilage oligomeric matrix protein) gene and association study in osteoarthrosis of the knee and hip joints

Osteoarthrosis (OA) is a common cause of musculoskeletal disability characterized by late-onset degeneration of articular cartilage. Although several candidate genes have been reported, susceptibility genes for OA remain to be determined. Hereditary osteochondral dysplasias produce severe, early-onset OA and hence are models for common idiopathic OA. Among them are pseudoachondroplasia and multiple epiphyseal dysplasia, both of which are caused by mutations in the cartilage oligomeric matrix protein (COMP) gene. Therefore, COMP may be a susceptibility gene for OA. We screened for polymorphisms by direct sequencing of all exons of the COMP gene with their flanking intron sequences and the promoter region. We identified 16 polymorphisms, of which 12 were novel. Using six polymorphisms spanning the entire COMP gene, we examined the association of COMP in Japanese patients with OA of the knee and hip joints. Genotype and allele frequencies of the polymorphisms were not significantly different between OA and control groups, and there was no significant difference in haplotypes. These results do not support an association between COMP and OA in the Japanese population. Received: March 30, 2001 / Accepted: May 7, 2001     

Ficolin Gene Polymorphisms in Systemic Lupus Erythematosus and Rheumatoid Arthritis

Systemic lupus erythemathosus (SLE) and rheumatoid arthritis (RA) are complex autoimmune diseases characterized by an immune balance breakdown and by chronic inflammation. Several findings link SLE and RA development with the complement system and ficolin components have emerged as candidates for disease development. Since genetic association studies with ficolin genes in SLE and RA have not yet been conducted in a Brazilian population, the aim of this study was to determine whether polymorphisms of ficolin‐1(FCN1) and ficolin‐2 (FCN2) genes are associated with SLE and RA susceptibility as well as disease manifestation. Two SNPs within FCN1 (rs2989727 and 1071583) and three in FCN2 (rs17514136, rs3124954, and rs7851696) were studied in 208 SLE and184 RA patients as well as 264 healthy individuals in a Southeast Brazilian population. For SLE patients, the FCN2 rs17514136 SNP was associated with a more severe disease (SLICC) (p = 0.0067). Furthermore, an association between the occurrence of nephritis and the T/T genotype for FCN2 rs3124954 SNP (p = 0.047, OR = 3.17, 95%CI = 1.34–7.5) was observed. No association was observed between the studied polymorphisms and RA development. Thus, our data support involvement of the FCN2 gene in the SLE phenotype.     

Identification of single-nucleotide and repeat polymorphisms in two candidate genes, interleukin 4 receptor (IL4RA) and signal transducer and activator of transcription protein 6 (STAT6), for Th2-mediated diseases

 We report here the identification of 26 single-nucleotide polymorphisms (SNPs) spanning a total of 147 kb in two candidate genes, IL4RA and STAT6, for atopic disorders. Fourteen novel SNPs were found in our population. We also report the identification of three novel polymorphic (CA) repeat regions in these genes. No insertion/deletion polymorphisms in AluY elements were detected. The encoded proteins of these two genes are part of a single signaling pathway, and therefore, functional polymorphisms in these genes could potentially lead to higher risk and susceptibility to atopic disorders. We also examined the allelic frequency and haplotypes of these polymorphisms in a control population. These data will be potentially useful for association studies designed to investigate the role of these genes in atopic disorders such as asthma, eczema, and allergic rhinitis. This is the first report on the polymorphic content of these two genes in the Indian population. Received: August 5, 2002 / Accepted: September 30, 2002     

Association of 12 polymorphic variants conferring genetic risk to lung cancer in Indian population: An extensive meta‐analysis

Candidate gene as well as genome‐wide association studies identified several polymorphic variants to be associated with lung cancer worldwide including in India. However, contradictory results have failed to estimate the overall effect of the polymorphic variants on the disease. Textmining was conducted on PubMed following specific search strings to gather all the publications related to genetic association with lung cancer in India. Out of 211 PubMed hits only 30 studies were selected for meta‐analysis following specific inclusion criteria. Heterogeneity between studies was calculated by Cochran's Q‐test (P < 0.05) and heterogeneity index (I²). Publication bias was visualized by funnel plots and Egger's regression test. For each variant, following a fixed‐effect model, summary odds ratio (OR) along with 95% confidence interval (CI) was estimated. The meta‐analysis revealed three polymorphic variants viz. ‘deletion polymorphism (del1) (OR = 1.39, 95% CI = 1.03–1.87, P = 0.027) in GSTT1’, ‘deletion polymorphism (del2) (OR = 1.30, 95% CI = 1.01–1.67, P = 0.038) in GSTM1’ and ‘rs1048943 (OR = 1.98, 95% CI = 1.27–3.10, P = 0.002) in CYP1A1’ to be associated with lung cancer. However, after multiple testing correction, only rs1048943 was found to be significantly associated (P value = 0.0321) with lung cancer. None of the polymorphic variants showed any evidence of heterogeneity between studies or of publication bias. Our meta‐analysis revealed strong association of rs1048943 in CYP1A1, but a suggestive association of deletion polymorphisms in GSTT1 and GSTM1 with lung cancer, which provides a comprehensive insight on the overall effect of the polymorphic variants, reported in various case–control studies on Indian population, on the risk of lung cancer development. Environ. Mol. Mutagen. 58:688–700, 2017. © 2017 Wiley Periodicals, Inc.     

Further Investigation of Linkage Disequilibrium SNPs and their Ability to Identify Associated Susceptibility Loci

There is currently considerable interest in the use of single‐nucleotide polymorphisms (SNPs) to map disease susceptibility genes. The success of this method will depend on a number of factors including the strength of linkage disequilibrium (LD) between marker and disease loci. We used a data set of SNP genotypings in the region of the APOE disease susceptibility locus to investigate the likely usefulness of SNPs in case‐control studies. Using the estimated haplotype structure surrounding and including the APOE locus, and assuming a codominant disease model, we treated each SNP in turn as if it were a disease susceptibility locus and obtained, for each disease locus and markers, the expected likelihood ratio test (LRT) to assess disease association.We were particularly interested in the power to detect association with the susceptibility polymorphism itself, the power of nearby markers to detect association, and the ability to distinguish between the susceptibility polymorphism and marker loci also showing association. We found that the expected LRT depended critically on disease allele frequencies. For disease loci with a reasonably common allele we were usually able to detect association. However, for only a subset of markers in the close neighbourhood of the disease locus was association detectable. In these cases we were usually, but not always, able to distinguish the disease locus from nearby associated marker loci. For some disease loci, no other loci demonstrated detectable association with the disease phenotype. We conclude that one may need to use very dense SNP maps in order to avoid overlooking polymorphisms affecting susceptibility to a common phenotype.     

Identification of sequence polymorphisms in two sulfation-related genes, PAPSS2 and SLC26A2, and an association analysis with knee osteoarthritis

Osteoarthritis (OA) is one of the most common musculoskeletal disorders and is characterized by degeneration of articular cartilage. Sulfation of extracellular ma-trix proteins in articular cartilage is an important step in maintaining normal cartilage metabolism. Two sulfation-related genes have been reported as the causal genes of severe chondrodysplasias: mutations in PAPSS2 (3′-phosphoadenosine 5′-phosphosulfate synthase 2) cause spondylo-epimetaphyseal dysplasia (SEMD), and mutations in SLC26A2 (solute carrier family 26, member 2) cause diastrophic dysplasia. Given their critical roles in cartilage metabolism and the severe phenotypes that result from mutations in these genes, we examined PAPSS2 and SLC26A2 as candidate susceptibility loci for OA. We identified sequence polymorphisms in the coding and core promoter regions of these genes and analyzed their potential association with knee OA within the Japanese population. Ten sequence polymorphisms were detected in PAPSS2 and five in SLC26A2. An association analysis showed suggestive association of one minor polymorphism in the promoter region of SLC26A2. This 4-bp adenine deletion allele, del4A, was over-represented in knee OA (P = 0.043, odds ratio = 3.43) and is thought to confer a minor susceptibility to knee OA within the Japanese population. Haplotype analysis showed no evidence of association with the two genes, however, excluding them as major susceptibility loci for knee OA. Received: May 7, 2001 / Accepted: June 21, 2001     

Intercellular adhesion molecule‐1 gene polymorphisms in Behçet’s disease

Intercellular adhesion molecule‐1 (ICAM‐1) gene polymorphisms have been implicated in the susceptibility to inflammatory diseases, including multiple sclerosis and inflammatory bowel disease. The expression of both soluble and tissue ICAM‐1 is increased in Behçet’s disease (BD) but the contribution of ICAM‐1 gene polymorphisms to this disease remains unknown. Associations with BD have been reported for genes within the MHC, including HLA‐B51, TNF and MICA, but the role of non‐MHC genes in BD remains largely unexplored. We have investigated the frequency of the R/G 241 and K/E 469 ICAM‐1 gene polymorphisms in 83 patients with BD disease and 103 healthy controls, all of Palestinian and Jordanian descent, and demonstrated an association between BD and the ICAM‐1 E469 allele (P_c = 0.046, OR = 2.1). Among patients, no association was found between the presence of ocular disease and ICAM‐1 polymorphisms. While the functional correlate of this polymorphism remains unclear, this finding indicates that a genetic polymorphism in the ICAM‐1 gene domain, which is independent of the MHC, may contribute to disease.     

The Impact of FOXP3 Polymorphism on the Risk of Allergic Rhinitis: A Meta‐Analysis

Polymorphisms of several genes were reported to be associated with the risk of allergic rhinitis. Here, we first conducted a meta‐analysis to evaluate the potential genetic association between the polymorphisms of the FOXP3 (Forkhead Box P3) gene and the susceptibility to allergic rhinitis. A total of 2671 relevant articles were initially retrieved from the databases of PubMed, Web of Science, Embase, WANFANG/CNKI and Scopus, and six eligible case‐control studies were finally enrolled in our meta‐analysis, according to our strict inclusion/exclusion criteria. Based on the extracted data, Mantel–Haenszel statistic, Cochrane's Q statistic, I² test, subgroup meta‐analysis, Begg's test, Egger's test and sensitivity analysis were performed via Stata/SE 12.0 software. The results of the Mantel–Haenszel statistic regarding rs3761548 showed that no significant difference was observed in the allergic rhinitis case and population‐based control group under the genetic models of A versus C, AA versus CC, CA+AA versus CC, AA versus CC+CA and carrier A versus C (all P‐value of Association Test, P_A > 0.05), apart from CA versus CC (P_A = 0.020). The similar results were obtained in the subgroup analysis of Asian. In addition, we did not obtain the positive result in the meta‐analysis of rs2232365 (all P_A > 0.05). We also excluded the presence of large publication bias through Begg's test and Egger's test, and we confirmed the stability of data by sensitivity analysis. In summary, no significant association between rs3761548, rs2232365 polymorphisms of the FOXP3 gene, and an increased susceptibility to allergic rhinitis was identified based on the published data; however, this conclusion should be confirmed by more studies with increased sample sizes.     

Association of interleukin‐16 polymorphisms with disease progression and susceptibility in endometriosis

Interleukin‐16 (IL‐16) is a multifunctional pro‐inflammatory cytokine that was previously found in association with complex disorders, and it is now cleared that this cytokine plays a critical role in regulation of cellular functions such as homoeostasis. Due to the complexity of endometriosis and its resemblance to cancer, we designed present case–control study to determine the effects of genetic polymorphisms of the human IL‐16 gene on Iranian women's susceptibility to endometriosis. A total of 126 patients with endometriosis (stages I–IV) and 144 healthy women as control group were recruited to the study. We genotyped four single nucleotide polymorphisms of IL‐16 gene (rs11556218 T>G, rs4778889 T>C, rs4072111 C>T and rs1131445 C>T). Genotyping was performed using PCR and restriction fragment length polymorphism. Our results showed that genotype distribution in two exonic polymorphisms including rs11556218 and rs4072111 was significantly different between Endometriosis patients and healthy individuals (P < 0.05). We have also found an association between rs4072111 and rs1131445 with progression to the severe stages (III–IV) of endometriosis (P < 0.05). Finally, we may conclude that IL‐16 gene polymorphisms are highly associated with increased risk of endometriosis and could be considered as a susceptibility factor for endometriosis.