Anna L. Peljto

Genome-wide association study identifies multiple susceptibility loci for pulmonary fibrosis

We performed a genome-wide association study of non-Hispanic, white individuals with fibrotic idiopathic interstitial pneumonias (IIPs; n = 1,616) and controls (n = 4,683), with follow-up replication analyses in 876 cases and 1,890 controls. We confirmed association with TERT at 5p15, MUC5B at 11p15 and the 3q26 region near TERC, and we identified seven newly associated loci (Pmeta = 2.4 × 10−8 to 1.1 × 10−19), including FAM13A (4q22), DSP (6p24), OBFC1 (10q24), ATP11A (13q34), DPP9 (19p13) and chromosomal regions 7q22 and 15q14-15. Our results suggest that genes involved in host defense, cell-cell adhesion and DNA repair contribute to risk of fibrotic IIPs.

Association Between the MUC5B Promoter Polymorphism and Survival in Patients With Idiopathic Pulmonary Fibrosis

IMPORTANCE Current prediction models of mortality in idiopathic pulmonary fibrosis (IPF), which are based on clinical and physiological parameters, have modest value in predicting which patients will progress. In addition to the potential for improving prognostic models, identifying genetic and molecular features that are associated with IPF mortality may provide insight into the underlying mechanisms of disease and inform clinical trials. OBJECTIVE To determine whether the MUC5B promoter polymorphism (rs35705950), previously reported to be associated with the development of pulmonary fibrosis, is associated with survival in IPF. DESIGN, SETTING, AND PARTICIPANTS Retrospective study of survival in 2 independent cohorts of patients with IPF: the INSPIRE cohort, consisting of patients enrolled in the interferon-γ1b trial (n = 438; December 15, 2003-May 2, 2009; 81 centers in 7 European countries, the United States, and Canada), and the Chicago cohort, consisting of IPF participants recruited from the Interstitial Lung Disease Clinic at the University of Chicago (n = 148; 2007-2010). The INSPIRE cohort was used to model the association of the MUC5B genotype with survival, accounting for the effect of matrix metalloproteinase 7 (MMP-7) blood concentration and other demographic and clinical covariates. The Chicago cohort was used for replication of findings. MAIN OUTCOMES AND MEASURES The primary end point was all-cause mortality. RESULTS The numbers of patients in the GG, GT, and TT genotype groups were 148 (34%), 259 (59%), and 31 (7%), respectively, in the INSPIRE cohort and 41 (28%), 98 (66%), and 9 (6%), respectively, in the Chicago cohort. The median follow-up period was 1.6 years for INSPIRE and 2.1 years for Chicago. During follow-up, there were 73 deaths (36 GG, 35 GT, and 2 TT) among INSPIRE patients and 64 deaths (26 GG, 36 GT, and 2 TT) among Chicago patients. The unadjusted 2-year cumulative incidence of death was lower among patients carrying 1 or more copies of the IPF risk allele (T) in both the INSPIRE cohort (0.25 [95% CI, 0.17-0.32] for GG, 0.17 [95% CI, 0.11-0.23] for GT, and 0.03 [95% CI, 0.00-0.09] for TT) and the Chicago cohort (0.50 [95% CI, 0.31-0.63] for GG, 0.22 [95% CI, 0.13-0.31] for GT, and 0.11 [95% CI, 0.00-0.28] for TT). In the INSPIRE cohort, the TT and GT genotypes (risk for IPF) were associated with improved survival compared with GG (hazard ratios, 0.23 [95% CI, 0.10-0.52] and 0.48 [95% CI, 0.31-0.72], respectively; P < .001). This finding was replicated in the Chicago cohort (hazard ratios, 0.15 [95% CI, 0.05-0.49] and 0.39 [95% CI, 0.21-0.70], respectively; P < .002). The observed association of MUC5B with survival was independent of age, sex, forced vital capacity, diffusing capacity of carbon monoxide, MMP-7, and treatment status. The addition of the MUC5B genotype to the survival models significantly improved the predictive accuracy of the model in both the INSPIRE cohort (C = 0.71 [95% CI, 0.64-0.75] vs C = 0.68 [95% CI, 0.61-0.73]; P < .001) and the Chicago cohort (C = 0.73 [95% CI, 0.62-0.78] vs C = 0.69 [95% CI, 0.59-0.75]; P = .01). CONCLUSIONS AND RELEVANCE Among patients with IPF, a common risk polymorphism in MUC5B was significantly associated with improved survival. Further research is necessary to refine the risk estimates and to determine the clinical implications of these findings.

The MUC5B variant is associated with idiopathic pulmonary fibrosis but not with systemic sclerosis interstitial lung disease in the European Caucasian population.

A polymorphism on the MUC5B promoter (rs35705950) has been associated with idiopathic pulmonary fibrosis (IPF) but not with systemic sclerosis (SSc) with interstitial lung disease (ILD). We genotyped the MUC5B promoter in the first 142 patients of the French national prospective cohort of IPF, in 981 French patients with SSc (346 ILD), 598 Italian patients with SSc (207 ILD), 1383 French controls and 494 Italian controls. A meta-analysis was performed including all American data available. The T risk allele was present in 41.9% of the IPF patients, 10.8% of the controls (P = 2×10–44), OR 6.3 [4.6–8.7] for heterozygous patients and OR 21.7 [10.4–45.3] for homozygous patients. Prevalence of the T allele was not modified according to age, gender, smoking in IPF patients. However, none of the black patients with IPF presented the T allele. The prevalence of the T risk allele was similar between French (10%) and Italian (12%) cohorts of SSc whatever the presence of an ILD (11.1% and 13.5%, respectively). Meta-analysis confirmed the similarity between French, Italian and American cohorts of IPF or SSc-ILD. This study confirms 1) an association between the T allele risk and IPF, 2) an absence of association with SSc-ILD, suggesting different pathophysiology.

CT Scan Findings of Probable Usual Interstitial Pneumonitis Have a High Predictive Value for Histologic Usual Interstitial Pneumonitis

BACKGROUND The current usual interstitial pneumonitis (UIP)/idiopathic pulmonary fibrosis CT scan classification system excludes probable UIP as a diagnostic category. We sought to determine the predictive effect of probable UIP on CT scan on histology and the effect of the promoter polymorphism in MUC5B (rs35705950) on histologic and CT scan UIP diagnosis. METHODS The cohort included 201 subjects with pulmonary fibrosis who had lung tissue samples obtained within 1 year of chest CT scan. UIP diagnosis on CT scan was categorized as inconsistent with, indeterminate, probable, or definite UIP by two to three pulmonary radiologists. Tissue slides were scored by two expert pulmonary pathologists. All subjects with available DNA (N = 200) were genotyped for rs35705950. RESULTS The proportion of CT scan diagnoses were as follows: inconsistent with (69 of 201, 34.3%), indeterminate (72 of 201, 35.8%), probable (34 of 201, 16.9%), and definite (26 of 201, 12.9%) UIP. Subjects with probable UIP on CT scan were more likely to have histologic probable/definite UIP than subjects with indeterminate UIP on CT scan (82.4% [28 of 34] vs 54.2% [39 of 72]; P = .01). CT scan and microscopic honeycombing were not associated with each other (P = .76). The minor (T) allele of the MUC5B polymorphism was associated with concordant CT scan and histologic UIP diagnosis (P = .03). CONCLUSIONS Probable UIP on CT scan is associated with a higher rate of histologic UIP than indeterminate UIP on CT scan suggesting that they are distinct groups and should not be combined into a single CT scan category as currently recommended by guidelines. CT scan and microscopic honeycombing may be dissimilar entities. The T allele at rs35705950 predicts a UIP diagnosis by both chest CT scan and histology.

The Pulmonary Fibrosis-Associated MUC5B Promoter Polymorphism Does Not Influence the Development of Interstitial Pneumonia in Systemic Sclerosis

BACKGROUND More than 80% of patients with systemic sclerosis (SSc) develop lung involvement, most commonly interstitial pneumonia (IP). We recently identified a common variant in the promoter region of MUC5B (rs35705950) that has a significant effect on the risk of developing both familial and sporadic forms of IP. We hypothesized that this MUC5B promoter polymorphism is also associated with IP in subjects with SSc. METHODS We examined the minor allele frequency of the MUC5B polymorphism among 231 subjects with SSc, 109 with IP, and 122 without IP. IP diagnosis was confirmed by HRCT imaging and defined as the presence of reticular infiltrates and/or honeycomb cysts. FVC and diffusing capacity of the lung for carbon monoxide (Dlco) were also assessed. RESULTS We found no association between IP and the MUC5B polymorphism among subjects with SSc (OR = 1.1, P = .80). The frequencies of the MUC5B polymorphism among subjects with SSc with IP (10.6%) and without IP (9.4%) were similar to the frequency observed in a population of unaffected control subjects (9.0%). In secondary analyses, we found the MUC5B polymorphism was not significantly associated with either FVC (P = .42) or Dlco (P = .06). No association with SSc-associated IP was found even when we used a more conservative definition of IP (FVC ≤ 70% and evidence of reticulations or honeycombing vs SSc FVC > 70% and no evidence of reticulation or honeycombing). CONCLUSIONS Although SSc-associated IP is clinically, radiologically, and histologically similar to other forms of IP, it appears to have distinct genetic risk factors. This study highlights the genetic and phenotypic heterogeneity of IP in general.

The MUC5B Promoter Polymorphism Is Associated With Idiopathic Pulmonary Fibrosis in a Mexican Cohort but Is Rare Among Asian Ancestries

BACKGROUND Polymorphisms in the MUC5B promoter, TOLLIP, and nine additional genetic loci have been associated with idiopathic pulmonary fibrosis (IPF) within non-Hispanic white populations. It is unknown whether these variants account for risk of IPF in other racial/ethnic populations. We conducted a candidate single nucleotide polymorphism (SNP) association study in cohorts of Mexican and Korean patients with IPF. METHODS We chose 12 SNPs from 11 loci that are associated with IPF among non-Hispanic whites and genotyped these SNPs in cohorts of Mexican (83 patients, 111 control subjects) and Korean (239 patients, 87 control subjects) people. Each SNP was tested for association with IPF, after adjusting for age and sex. RESULTS The MUC5B promoter SNP rs35705950 was associated with IPF in the Mexican (OR = 7.36, P = .0001), but not the Korean (P = .99) cohort. The SNP in IVD (chromosome15, rs2034650) was significantly associated with pulmonary fibrosis in both the Mexican (OR = 0.40, P = .01) and Korean (OR = 0.13, P = .0008) cohorts. In the Korean cohort, there were no other variants associated with disease. In the Mexican cohort, SNPs on chromosomes 3, 4, and 11 were also associated with disease. CONCLUSIONS The strongest identified genetic risk factor for IPF among the non-Hispanic white population, the MUC5B promoter polymorphism, is also a strong risk factor in a Mexican population, but is very rare in a Korean population. The majority of genetic variants that account for risk of IPF in groups other than non-Hispanic whites are unknown. Hispanic and Asian populations should be studied separately to identify genetic risk loci for IPF.

Erratum: Genome-wide association study identifies multiple susceptibility loci for pulmonary fibrosis (Nature Genetics (2013) 45 (613-620))

Tasha E Fingerlin, Elissa Murphy, Weiming Zhang, Anna L Peljto, Kevin K Brown, Mark P Steele, James E Loyd, Gregory P Cosgrove, David Lynch, Steve Groshong, Harold R Collard, Paul J Wolters, Williamson Z Bradford, Karl Kossen, Scott D Seiwert, Roland M du Bois, Christine Kim Garcia, Megan S Devine, Gunnar Gudmundsson, Helgi J Isaksson, Naftali Kaminski, Yingze Zhang, Kevin F Gibson, Lisa H Lancaster, Joy D Cogan, Wendi R Mason, Toby M Maher, Philip L Molyneaux, Athol U Wells, Miriam F Moffatt, Moises Selman, Annie Pardo, Dong Soon Kim, James D Crapo, Barry J Make, Elizabeth A Regan, Dinesha S Walek, Jerry J Daniel, Yoichiro Kamatani, Diana Zelenika, Keith Smith, David McKean, Brent S Pedersen, Janet Talbert, Raven N Kidd, Cheryl R Markin, Kenneth B Beckman, Mark Lathrop, Marvin I Schwarz & David A Schwartz Nat. Genet. 45, 613–620 (2013); published online 14 April 2013; corrected after print 1 October 2013