Effects of the programmed cell death 1 (PDCD1) polymorphisms in susceptibility to systemic lupus erythematosus

The failure of immunological tolerance to self‐antigens plays a fundamental role in the pathogenesis of systemic lupus erythematosus (SLE). PD‐1 is an inhibitory receptor for regulating the immune system and preventing development of autoimmune disorders. This study aimed to determine the role of four single‐nucleotide polymorphisms (SNPs) within programmed cell death 1 (PDCD1 or PD‐1) gene and haplotypes defined by these SNPs in susceptibility to SLE in the Iranian population. Blood samples were obtained from 253 SLE and 564 healthy subjects. Red blood cells were lysed and genomic DNAs were extracted using salting‐out method. Genotype determinations of PD1.1, PD1.3, PD1.5 and PD1.9 SNPs were performed by polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP), and 12 haplotypes were constructed by PDCD1 SNPs. Our results showed significant differences in PD1.5 genotype frequencies between patient and control groups (p < .001). The frequencies of PD1.5 C/C, C/T and T/T genotypes versus other genotypes in SLE patients significantly differed from healthy subjects (p < .001, p = .001 and p = .002, respectively). Allelic analysis indicated a significant association between the frequency of PD1.5C allele and development of SLE in our population (odds ratio [OR] = 1.91, 95% confidence interval [CI] = 1.51–2.42, p < .001). At the haplotype level, GGCC, GACT and GGCT haplotypes were significantly different between SLE and control groups (OR = 2.14, 95% CI = 1.73–2.66, p < .001; OR = 9.76, 95% CI = 4.47–21.3, p < .001; and OR = 0.32, 95% CI = 0.24–0.42, p < .001, respectively). Based on these findings, PD1.5 SNP and some haplotypes of PDCD1 contribute to SLE risk in the Iranian population.     

Association of PDCD1 polymorphisms with childhood-onset systemic lupus erythematosus

A regulatory single nucleotide polymorphism (SNP) PD1.3G/A located on programmed cell death 1 (PDCD1) gene, was shown to be involved in susceptibility to systemic lupus erythematosus (SLE) in Swedish, European American, and Mexican cases. However, association to childhood-onset SLE has not been analyzed. The aim of this study was to investigate the association of PDCD1 polymorphisms and haplotypes with susceptibility to childhood-onset SLE in Mexican population. Three PDCD1 SNPs, PD1.3G/A, PD1.5C/T, PD1.6G/A, were analyzed in 250 childhood-onset SLE Mexican patients and 355 healthy controls in a case-control association study. Polymorphisms were genotyped by TaqMan technology. Stratification analysis was performed on the SLE cohort to investigate the SNP association with renal disorder. In addition, haplotypes were constructed with these three SNPs. The PD1.3A allele was significantly associated to childhood-onset SLE (P=0.0019, odds ratio (OR) 2.73, 95% confidence interval (95% CI) 1.35-5.56). The other PDCD1 SNPs did not show association. A total of 155 patients (62%) had nephritis, and no association was observed with PDCD1 SNPs. The ACG haplotype (PD1.3A, PD1.5C, PD1.6G) included almost all PD1.3A alleles, and it was more frequent in SLE patients (5.5%) than in controls (2.1%) (P=0.003; OR 2.73, 95% CI 1.37-5.46). The haplotype structure in Mexican controls was significantly different from those reported in Spanish and Swedish. Our results support association of the PD1.3A SNP to susceptibility of childhood-onset SLE in Mexican population and does not show association to lupus nephritis in this age group.     

PDCD1 single nucleotide genes polymorphisms confer susceptibility to juvenile-onset systemic lupus erythematosus

Abstract

Juvenile-onset systemic lupus erythematosus (JSLE) is a multisystem autoimmune disease in which both the genetic and environmental factors seem to be involved in the etiopathogenesis of the disease. The aim of this study was to evaluate the association of programmed cell death 1 (PDCD1, also called PD-1) gene polymorphisms with JSLE susceptibility in Iranian population. In this case-control association study, three PDCD1 SNPs, including PD-1.1 G/A, PD-1.3 G/A and PD-1.9 C/T were genotyped in 50 Iranian patients with JSLE and 202 healthy unrelated controls, using PCR-RFLP method. The PD-1.1 A allele was found to be more frequent in the case group compared with controls (6% vs. 1.5%, p?=?0.024). Moreover, the GG genotype was less frequent in cases than in controls (88% vs. 97%, p?=?0.021). The other PDCD1 SNPs did not show association. At the haplotypic level, no significant differences was recognized between the two groups of case and control neither for the GAC (PD-1.1 G, PD-1.3 A, PD-1.9 C) nor for the GGC haplotype (PD-1.1 G, PD-1.3 G, PD-1.9 C). Our findings support the influence of the PD1.1 A SNP on the development of JSLE in Iranian population.     

Polymorphisms of <Emphasis Type="Italic">PTPN11</Emphasis> Coding SHP-2 as Biomarkers for Ulcerative Colitis Susceptibility in the Japanese Population

Objective  To identify genetic determinants of inflammatory bowel disease (IBD), we examined an association between polymorphisms of both the programmed cell death 1 gene (PDCD1) and the src homology 2 domain-containing tyrosine phosphatase 2 gene (PTPN11) and susceptibility to IBD. Methods  Study subjects comprised 114 patients with ulcerative colitis (UC), 83 patients with Crohn’s disease, and 200 healthy control subjects. Five single nucleotide polymorphisms (SNPs) in PDCD1 and PTPN11 were detected by polymerase chain reaction restriction fragment length polymorphism. Subsequently, haplotypes composed of the two SNPs in PTPN11 were constructed. Results  The frequencies of the Hap 1 haplotype and its homozygous Hap 1/Hap 1 diplotype of PTPN11 were significantly increased in UC patients compared to control subjects (P = 0.011 and P = 0.030, respectively). While no association was found for PDCD1 for UC or CD and none for PTPN11 for CD. Conclusion   PTPN11 is a genetic determinant for the pathogenesis of UC, and haplotyping of PTPN11 may be useful as a genetic biomarker to identify high-risk individuals susceptible to UC.     

Failure to confirm association between PDCD1 polymorphisms and rheumatoid arthritis in a Japanese population

Programmed cell death 1 (PDCD1) is a necessary negative regulator to maintain peripheral tolerance and is a key molecule in the development of autoimmune diseases. Although PDCD1 gene polymorphisms and haplotypes were reported to be associated with rheumatoid arthritis (RA), replication studies later on showed conflicting results. Here, we analyzed the association of PDCD1 with RA using a large series of Japanese RA patients and population-based controls. DNA samples were obtained from 1,504 RA patients and 449 sex-matched controls. All samples were genotyped for three SNPs on PDCD1 (PD-1.1, PD-1.3 and PD-1.5) using the TaqMan fluorogenic 5′ nuclease assay. Chi-square testing was performed for a case-control study, and the PENHAPLO program was used for haplotype estimation. We could not observe any significant association of PD-1.1 or PD-1.5 polymorphisms between RA. PD-1.3, which was reported to be involved in susceptibility to RA in patients of European descent, was non-polymorphic in the Japanese population. We conclude that polymorphisms in the PDCD1 gene analyzed here are not associated with RA in a Japanese population.     

IL‐1A rs1800587, IL‐1B rs1143634 and IL‐1R1 rs2234650 polymorphisms in Iranian patients with systemic sclerosis

Systemic Sclerosis (SSc) is a systemic autoimmune disorder, with ambiguous pathogenesis. Genetic and environmental factors were proved to be correlated with SSc aetiology. Single nucleotide polymorphisms (SNPs) in cytokine genes can alter the structure and function of the cytokines and consequently may increase the susceptibility to a specific disease. In this study, we investigated SNPs of the IL‐1 gene cluster in Iranian SSc patients. We obtained blood samples from 170 SSc patients and 213 healthy individuals. Cytokine genotyping results were obtained by polymerase chain reaction with sequence‐specific primers (PCR‐SSP). IL‐1A rs1800587, IL‐1B rs1143634 and IL‐1R1 rs2234650 were evaluated for SNP study. The frequency of the IL‐1B rs1143634 CT genotype was significantly lower in SSc patients compared to the controls (OR = 0.584; 95% CI = 0.385–0.886; P‐value = 0.023), so we propose that CT genotype of this allele might be protective. According to our haplotype analysis, CCC haplotype frequency is higher in the control group compared to SSc patients (OR = 1.575; 95% CI = 1.176–2.111; P‐value = 0.008) and in contrast, CTC haplotype frequency is lower in the control group compared to SSc patients (OR = 0.152; 95% CI = 0.047–0.484; P‐value = 0.002), so they might decrease and increase the susceptibility of having SSc, respectively. In addition, we reported two significant diplotypes frequency differences among SSc patients and healthy individuals. It is highly important that there is not much resemblance between the IL‐1 gene cluster polymorphism in different populations, so we can indicate that SNPs may play critical roles when they are combined with other genetic and environmental factors.     

Genetic variation in arsenic (+3 oxidation state) methyltransferase (AS3MT), arsenic metabolism and risk of basal cell carcinoma in a European population

Exposure to inorganic arsenic increases the risk of basal cell carcinoma (BCC). Arsenic metabolism is a susceptibility factor for arsenic toxicity, and specific haplotypes in arsenic (+3 oxidation state) methyltransferase (AS3MT) have been associated with increased urinary fractions of the most toxic arsenic metabolite, methylarsonic acid (MMA). The aim of this study is to elucidate the association of AS3MT haplotypes with arsenic metabolism and the risk of BCC. Four AS3MT polymorphisms were genotyped in BCC cases (N = 529) and controls (N = 533) from Eastern Europe with low to moderate arsenic exposure (lifetime average drinking water concentration: 1.3 µg/L, range 0.01–167 µg/L). Urinary metabolites [inorganic arsenic (iAs), MMA, dimethylarsinic acid (DMA)] were analyzed by HPLC‐ICPMS. Five AS3MT haplotypes (based on rs3740400 A/C, rs3740393 G/C, rs11191439 T/C and rs1046778 T/C) had frequencies >5%. Individuals with the CCTC haplotype had lower %iAs (P = 0.032) and %MMA (P = 0.020) in urine, and higher %DMA (P = 0.033); individuals with the CGCT haplotype had higher %MMA (P < 0.001) and lower %DMA (P < 0.001). All haplotypes showed increased risk of BCC with increasing arsenic exposure through drinking water (ORs 1.1–1.4, P values from <0.001 to 0.082), except for the CCTC haplotype (OR 1.0, CI 0.9–1.2, P value 0.85). The results suggest that carriage of AS3MT haplotypes associated with less‐efficient arsenic methylation, or lack of AS3MT haplotypes associated with a more‐efficient arsenic methylation, results in higher risk of arsenic‐related BCC. The fact that AS3MT haplotype status modified arsenic metabolism, and in turn the arsenic‐related BCC risk, supports a causal relationship between low‐level arsenic exposure and BCC. Environ. Mol. Mutagen. 56:60–69, 2015. © 2014 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society     

Decreased risk for myocardial infarction and lower tumor necrosis factor-alpha levels in carriers of variants of the PDCD1 gene

Increasing interest has been directed toward the inflammatory mechanisms involved in the pathogenesis of myocardial infarction (MI). In the search for genetic mechanisms underlying these inflammatory components, we studied variants of programmed cell death-1 (PDCD1), an immunoinhibitory receptor that inhibits lymphocyte activation and cytokine production, previously shown to be associated with several autoimmune disorders. The PD1.1, PD1.3, and PD1.6 polymorphisms of the PDCD1 gene were typed in the Stockholm Heart Epidemiology Program, a population-based clinical material consisting of 1179 first-time MI case patients and 1528 unaffected control subjects. Individual alleles and haplotypes were studied for association with levels of the inflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin-6, and C-reactive protein and risk for MI. We observed a weak protective effect of PD1.3A allele for MI (odds ratio: 0.78, 95% confidence interval: 0.61-0.98). We also observed decreased levels of TNF-alpha in carriers of the PD1.1A/PD1.3G/PD1.6A haplotype, which is consistent with our previous observation that this haplotype may be protective from autoimmune conditions. Carriers of variants of the PDCD1 gene exhibit a decreased risk for nonfatal myocardial infarction, and PDCD1 mediates variation in TNF-alpha levels.     

Association between human leucocyte antigen alleles and risk of stroke in Iranian population

Previous studies have demonstrated associations between human leucocyte antigen (HLA) and some types of ischaemic stroke. In the present study, we genotyped HLA‐A,‐B and ‐DRB1 alleles in 140 Iranian patients with history of ischaemic stroke and 140 age‐/sex‐matched healthy subjects. No significant difference has been found in the distribution of HLA‐A and B alleles between cases and controls. The DRB1*16 allele was significantly over‐represented in patient group compared with control group (Adjusted p value = 0.048). Other HLA‐DRB1 alleles were not associated with stroke risk. The HLA‐B*35,B*52 genotype was significantly more prevalent among patients compared with controls (Adjusted p value = 0.03, OR [95% CI] = 9.3 [1.3, 407.2]). Several HLA haplotypes were associated with risk of stroke in the assessed population. The current study provides further evidences for participation of HLA in conferring risk of ischaemic stroke.     

Association of PDCD1 genetic variation with risk and clinical manifestations of systemic lupus erythematosus in a multiethnic cohort

We evaluated the roles of five single-nucleotide polymorphisms (SNPs) within PDCD1, and haplotypes defined by these SNPs, for the development of systemic lupus erythematosus (SLE) and specific sub-phenotypes (nephritis, antiphospholipid antibody positive, arthritis and double-stranded DNA positive) within a multiethnic US cohort of 1036 patients. Family based analyses were performed using 844 simplex families from four ethnic groups (Caucasian, Asian, Hispanic and African American). Subjects were genotyped for five 'tag' SNPs (selected from 15) to provide complete genetic information in all main ethnic groups. We employed transmission disequilibrium testing to assess risk for SLE by allele or haplotype, and multiple logistic regression analysis of SLE cases to examine associations with specific sub-phenotypes. In family based analyses, a haplotype containing the PD1.3A allele was significantly associated with SLE susceptibility among Caucasian families (P=0.01). Among Hispanic families, two novel SNPs were associated with SLE risk (P=0.005 and 0.01). In multivariate logistic regression analyses, five haplotypes were associated with specific sub-phenotypes among the different ethnic groups. These results suggest that PDCD1 genetic variation influences the risk and expression of SLE and that these associations vary according to ethnic background.     

Association of MAPT haplotype-tagging SNPs with sporadic Parkinson's disease

Mutations in the tau gene (MAPT) have been found in families with frontotemporal dementia with parkinsonism linked to chromosome 17. In addition, the MAPT H1-clade specific sub-haplotype, H1c, has been strongly associated with the tauopathies, progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) and, to a lesser extent, with Alzheimer's disease (AD). In Parkinson's disease (PD), there have been several reports of association with the MAPT H1-clade. Although weak to inconclusive, this association is supported by meta-analyses of the various studies. To further investigate this baffling role of MAPT in PD, six haplotype-tagging SNPs were genotyped in a large cohort of sporadic PD cases; 324 pathologically confirmed and 248 clinically diagnosed, and 660 controls. In the single-locus association analysis, the H1-clade was associated with an increased risk of PD (p = 0.032). In the haplotype-analysis, the sole H2-derived haplotype was under-represented in all of the PD cases compared to controls (p = 0.03). There was no significant difference in the distribution of any of the common haplotypes derived from the H1-clade background. Our study supports the hypothesis that genetic variability in the MAPT gene confers susceptibility to PD. However, the effect is not strong, and the H1c haplotype is not involved, suggesting a mechanism that is distinct to that involved in the associated tauopathies and may be explained by the H1/H2 inversion.     

Interleukin 10 gene promoter polymorphisms (rs1800896, rs1800871 and rs1800872) and haplotypes are associated with the activity of systemic lupus erythematosus and IL10 levels in an Iranian population

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with unknown aetiology. According to the role of interleukin 10 (IL10) in SLE pathogenesis, the genetic alterations in its promoter region could be associated with elevated IL10 levels and exacerbated disease. Here, we investigated the association of genotype and haplotype frequencies of three IL10 gene promoter polymorphisms with susceptibility to SLE, IL10 plasma levels and disease activity of patients in an Iranian population. A total of 116 SLE patients and 131 healthy subjects were enrolled. The PCR‐RFLP technique was used to detect IL10 promoter genotypes at the positions of ?1082 (G/A), ?819 (C/T) and ?592 (C/A) in association with IL10 plasma levels and SLEDAI scores. The GG genotype of ?1082 polymorphism was associated with the increased risk of SLE [OR = 2.65, 95% CI (1.21–5.82), p‐value = 0.046]. The CC genotype in ?819 region was associated with SLE susceptibility [OR = 3.38, 95% CI (1.26–9.07), p‐value = 0.034] and C allele was introduced as risk allele [OR = 1.86, 95% CI (1.15–3.01), p‐value = 0.009] in this region. IL10 plasma levels were overexpressed in CC genotype carriers of ?592 SNP and decreased in AA genotype carriers of ?1082. IL10 was also increased in SLE patients with CGT (?592/?1082/?819) haplotype. The SLEDAI score was higher among CC genotype carriers at the position of ?592 and TT genotype carriers at the region of ?819. SLEDAI was also elevated among patients with CGC (?592/?1082/?819) and CAC (p = 0.011) haplotypes. The present study suggests that the IL10 –819(C/T), ?1082(G/A) and ?592(C/A) polymorphisms and the haplotypes are associated with SLE susceptibility, increased disease activity and elevated IL10 levels. While this is the first time to report such an association in an Iranian population, further studies are needed to confirm these findings.     

Haplotype analysis of HLA‐A, ‐B antigens and ‐DRB1 alleles in south Indian HIV‐1‐infected patients with and without pulmonary tuberculosis

We have shown earlier the association of human leucocyte antigen (HLA)‐A11 with resistance and HLA‐B40 and ‐DR2 with susceptibility to HIV and HIV‐TB. In the present study, we have attempted to find out the HLA‐DR2 subtypes and the possible HLA‐A/‐B/‐DRB1 haplotype combinations that are associated with susceptibility or resistance to HIV and HIV with pulmonary tuberculosis (HIV+PTB+). HLA‐DR2 subtyping was carried out by polymerase chain reaction‐based sequence‐specific oligonucleotide probe method. Overrepresentation of HLA‐DRB1*1501 in HIV‐positive PTB‐negative (HIV+PTB–) patients (P = 0.004, P_c = 0.06) and ‐DRB1*1502 in HIV‐positive PTB‐positive (HIV+PTB+) patients (P = 0.019) was observed as compared to healthy controls. Haplotype analysis revealed an increased frequency of HLA‐A2‐DRB1*1501 haplotype in HIV+PTB– patients (P = 0.008) and HLA‐A2‐DRB1*1502 among HIV+PTB+ patients (P = 0.01) compared to healthy controls. The haplotypes B40‐DRB1*1501 and B40‐DRB1*04 were found to be moderately increased in HIV+PTB– and HIV+PTB+ patients (P < 0.05). The study suggests that HLA‐A2‐DRB1*1501 haplotype may be associated with HIV infection while HLA‐A2‐DRB1*1502 haplotype might be associated with susceptibility to PTB in HIV patients. Moreover, HLA‐B40‐DRB1*1501 and HLA‐B40‐DRB1*04 haplotypes may be associated with susceptibility to HIV infection and to PTB in HIV patients.     

HLA‐DRA is associated with Parkinson's disease in Iranian population

The rs3129882, a noncoding variant in HLA‐DR, was found to be associated with Parkinson's disease (PD) using several genome‐wide association studies. The aim of this replication study was to explore the relationship between this variant and PD in Iranian population. Genomic DNA was extracted from peripheral blood samples, and the rs3129882 SNP was genotyped using a PCR‐RFLP method in 520 PD patients and 520 healthy Iranian controls. Significant differences were found in allele frequencies between patients and controls (χ² = 4.64, P = 0.031). Under additive and dominant models, the association of the SNP with PD risk is significant, where the A allele was observed to be protective. The results suggest that rs3129882 polymorphism may be a risk factor for PD in Iranian. This is the first study reporting such an association in this population. More replication studies are needed to confirm this data.     

Association of the HLA‐G 3′UTR polymorphisms with colorectal cancer in Italy: a first insight

This study aimed to explore functional and regulatory polymorphisms and haplotypes at the HLA‐G 3′UTR region in colorectal cancer development. The presence of nonpolymorphic variants was also evaluated. Three‐hundred and eight patients with colorectal cancer and 294 healthy controls were analysed at the germinal level. We found an association with increased risk of colorectal cancer for +2960 14‐bp INDEL, +3196 C>G SNPs and UTR‐2 haplotype, and a ‘protective’ role for +3003 T>C, +3010 C>G polymorphisms and UTR‐4 haplotype. We detected in 3 distinct patients, a novel nucleotide change (+3037 C>A) and 2 already described rare variants, +3032 G/C (EUR MAF = 0.1%) and +3092 G/T (EUR MAF = 0%). This is the first study showing associations between different polymorphisms in the HLA‐G 3′UTR and colorectal cancer susceptibility.     

Relationship between programmed cell death‐1 polymorphisms and clearance of hepatitis B virus

Programmed cell death‐1 (PD‐1) plays a critical role in regulating T‐cell function during hepatitis B virus (HBV) infection. This study investigated the relationship between the polymorphisms of PD‐1 gene and the susceptibility to HBV infection. Single nucleotide polymorphisms (SNPs) in PD‐1 gene at positions +7146 G>A (guanine to adenine substitution) and +7209 C>T (cytosine to thymine substitution) were analysed using a polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) method in 220 subjects with chronic hepatitis B infection and 165 spontaneous clearance of HBV subjects. However, no statistically significant differences were found in the genotype distributions of the PD‐1 +7146 G>A and PD‐1 +7209 C>T polymorphisms among chronic hepatitis B and spontaneous clearance subjects. According to stratified analyses, borderline significance was observed between PD‐1 +7146 GA genotype and risk of HBV chronicity in the subgroup of male gender (OR = 1.88, 95% 0.95–3.71; P = 0.07). Our findings demonstrate for the first time that the PD‐1 +7146 G>A and PD‐1 +7209 C>T polymorphisms have not been any major role in genetic susceptibility to chronicity of HBV infection, at least in the population studied here. Independent studies are needed to validate our findings in a larger series, as well as in patients of different ethnic origins.     

Association of hepatocellular carcinoma risk with polymorphisms in tumour necrosis factor alpha gene in a Chinese Han population

Hepatocellular carcinoma (HCC) is the third leading cause of cancer‐related death worldwide. Studies have shown that the tumour necrosis factor alpha (TNF‐α) plays an important role in the development of HCC; however, the association between genetic variations of TNF‐α and HCC is not yet fully understood. To evaluate the correlation of TNF‐α polymorphisms with HCC, we randomly selected 327 HCC patients and 432 healthy controls, all these subjects reported Han nationality. Genotyping of four TNF‐α SNPs (rs1799724, rs1800629, rs1799964 and rs1800610) was performed using the matrix‐assisted laser desorption ionization‐time of flight mass spectrometry (MALDI‐TOF‐MS) method. Distributions of rs1799964 genotypes and rs1800610 alleles were found to be significantly different between cases and controls (p = .011, p = .001). The recessive model of rs1799964 significantly increased HCC risk (p = .0015), while the dominant and over‐dominant models of rs1800610 significantly reduced HCC risk (p = .0096, p = .014). Haplotype analysis of the four TNF‐α SNPs revealed that the TGTA haplotype was associated with a reduced HCC risk (p = .0033, OR = 0.53), while the TGTG haplotype was associated with an increased HCC risk (p = .0032, OR = 9.69). These findings indicated that specific TNF‐α polymorphisms may be associated with the susceptibility to HCC.     

Genetic susceptibility to severe asthma with fungal sensitization

Severe asthma is problematic and its pathogenesis poorly understood. Fungal sensitization is common, and many patients with severe asthma with fungal sensitization (SAFS), used to denote this subgroup of asthma, respond to antifungal therapy. We have investigated 325 haplotype‐tagging SNPs in 22 candidate genes previously associated with aspergillosis in patients with SAFS, with comparisons in atopic asthmatics and healthy control patients, of whom 47 SAFS, 279 healthy and 152 atopic asthmatic subjects were genotyped successfully. Significant associations with SAFS compared with atopic asthma included Toll‐like receptor 3 (TLR3) (p = .009), TLR9 (p = .025), C‐type lectin domain family seven member A (dectin‐1) (p = .043), interleukin‐10 (IL‐10) (p = .0010), mannose‐binding lectin (MBL2) (p = .007), CC‐chemokine ligand 2 (CCL2) (2 SNPs, p = .025 and .041), CCL17 (p = .002), plasminogen (p = .049) and adenosine A2a receptor (p = .024). These associations differ from those found in ABPA in asthma, indicative of contrasting disease processes. Additional and broader genetic association studies in SAFS, combined with experimental work, are likely to contribute to our understanding of different phenotypes of problematic asthma.