Dataset Information

Heritability of chronic obstructive pulmonary disease and related phenotypes in smokers.

ABSTRACT:

Rationale

Previous studies of chronic obstructive pulmonary disease (COPD) have suggested that genetic factors play an important role in the development of disease. However, single-nucleotide polymorphisms that are associated with COPD in genome-wide association studies have been shown to account for only a small percentage of the genetic variance in phenotypes of COPD, such as spirometry and imaging variables. These phenotypes are highly predictive of disease, and family studies have shown that spirometric phenotypes are heritable.

Objectives

To assess the heritability and coheritability of four major COPD-related phenotypes (measurements of FEV1, FEV1/FVC, percent emphysema, and percent gas trapping), and COPD affection status in smokers of non-Hispanic white and African American descent using a population design.

Methods

Single-nucleotide polymorphisms from genome-wide association studies chips were used to calculate the relatedness of pairs of individuals and a mixed model was adopted to estimate genetic variance and covariance.

Measurements and main results

In the non-Hispanic whites, estimated heritabilities of FEV1 and FEV1/FVC were both about 37%, consistent with estimates in the literature from family-based studies. For chest computed tomography scan phenotypes, estimated heritabilities were both close to 25%. Heritability of COPD affection status was estimated as 37.7% in both populations.

Conclusions

This study suggests that a large portion of the genetic risk of COPD is yet to be discovered and gives rationale for additional genetic studies of COPD. The estimates of coheritability (genetic covariance) for pairs of the phenotypes suggest considerable overlap of causal genetic loci.

SUBMITTER: Zhou JJ

PROVIDER: S-EPMC3826281 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:RationaleSleep disturbance frequently affects patients with chronic obstructive pulmonary disease (COPD), and is associated with reduced quality of life and poorer outcomes. Data indicate that smokers with preserved pulmonary function have clinical symptoms similar to those meeting spirometric criteria for COPD, but little is known about the driving factors for sleep disturbance in this population of emerging interest.ObjectivesTo compare the magnitude and correlates of sleep disturbance between smokers with preserved pulmonary function and those with airflow obstruction.MethodsUsing cross-sectional data from the COPD Outcomes-Based Network for Clinical Effectiveness and Research Translation multicenter registry, we identified participants clinically identified as having COPD with a smoking history of at least 20 pack-years and either preserved pulmonary function or airflow obstruction. We quantified sleep disturbance by T-score measured in the sleep disturbance domain of the Patient-Reported Outcomes Information System questionnaire, and defined a minimum important difference as a T-score difference of two points. We performed univariate and multivariable linear regression to evaluate correlates within each group.ResultsWe identified 100 smokers with preserved pulmonary function and 476 with airflow obstruction. The sleep disturbance T-score was 4.1 points greater among individuals with preserved pulmonary function (95% confidence interval [CI], 2.0-6.3). In adjusted analyses, depression symptom T-score was associated with sleep disturbance in both groups (airflow obstruction: β, 0.61 points; 95% CI, 0.27-0.94; preserved pulmonary function: β, 0.25 points; 95% CI, 0.12-0.38). Of note, lower percent predicted FEV1 was associated with greater sleep disturbance among those with preserved pulmonary function (β, -0.19 points; 95% CI, -0.31 to -0.07), whereas higher FEV1 was associated with greater sleep disturbance among individuals with airflow obstruction (β, 0.06 points; 95% CI, 0.01-0.10).ConclusionsAmong smokers with clinically identified COPD, the severity of sleep disturbance is greater among those with preserved pulmonary function compared with those with airflow obstruction. Nonrespiratory symptoms, such as depression, were associated with sleep disturbance in both groups, whereas the relationship of sleep disturbance with FEV1 differed.