MUC5B promoter polymorphism and interstitial lung abnormalities

Abstract

Background: A common promoter polymorphism (rs35705950) in MUC5B, the gene encoding mucin 5B, is associated with idiopathic pulmonary fibrosis. It is not known whether this polymorphism is associated with interstitial lung disease in the general population.

Methods: We performed a blinded assessment of interstitial lung abnormalities detected in 2633 participants in the Framingham Heart Study by means of volumetric chest computed tomography (CT). We evaluated the relationship between the abnormalities and the genotype at the rs35705950 locus.

Results: Of the 2633 chest CT scans that were evaluated, interstitial lung abnormalities were present in 177 (7%). Participants with such abnormalities were more likely to have shortness of breath and chronic cough and reduced measures of total lung and diffusion capacity, as compared with participants without such abnormalities. After adjustment for covariates, for each copy of the minor rs35705950 allele, the odds of interstitial lung abnormalities were 2.8 times greater (95% confidence interval [CI], 2.0 to 3.9; P<0.001), and the odds of definite CT evidence of pulmonary fibrosis were 6.3 times greater (95% CI, 3.1 to 12.7; P<0.001). Although the evidence of an association between the MUC5B genotype and interstitial lung abnormalities was greater among participants who were older than 50 years of age, a history of cigarette smoking did not appear to influence the association.

Conclusions: The MUC5B promoter polymorphism was found to be associated with interstitial lung disease in the general population. Although this association was more apparent in older persons, it did not appear to be influenced by cigarette smoking. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT00005121.).

Figure 1. Computed Tomographic Images of Two Participants with Lung Abnormalities

Shown are axial images (Panels A and B) and coronal images (Panels C and D) obtained from two participants in the Framingham Heart Study. Panels A and C (Participant 1) show representative features of interstitial lung abnormalities, and Panels B and D (Participant 2) show pulmonary parenchymal architectural distortion highly suggestive of a fibrotic lung disease (definite fibrosis).

Figure 2. MUC5B Genotype According to Lung Abnormality Status and Age Group

Data from 2633 participants from the Framingham Heart Study are shown according to the MUC5B promoter genotype (35705950 G/G, G/T, or T/T), stratified by lung abnormality status and age (≤50 years vs. >50 years). CT denotes computed tomography, FHS-MDCT2 Framingham Heart Study Multidetector Computed Tomography 2, and ILA interstitial lung abnormalities.