title: Genetic ancestry and the relationship of cigarette smoking to lung function and per cent emphysema in four race/ethnic groups: a cross-sectional study.
abstract: BACKGROUND
  Cigarette smoking is the major cause of chronic obstructive pulmonary disease and emphysema. Recent studies suggest that susceptibility to cigarette smoke may vary by race/ethnicity; however, they were generally small and relied on self-reported race/ethnicity.
  
  
  OBJECTIVE
  To test the hypothesis that relationships of smoking to lung function and per cent emphysema differ by genetic ancestry and self-reported race/ethnicity among Caucasians, African-Americans, Hispanics and Chinese-Americans.
  
  
  METHODS
  Cross-sectional population-based study of adults age 45-84 years in the USA.
  
  
  METHODS
  Principal components of genetic ancestry and continental ancestry estimated from one million genome-wide single nucleotide polymorphisms; pack-years of smoking; spirometry measured for 3344 participants; and per cent emphysema on computed tomography for 8224 participants.
  
  
  RESULTS
  The prevalence of ever-smoking was: Caucasians, 57.6%; African-Americans, 56.4%; Hispanics, 46.7%; and Chinese-Americans, 26.8%. Every 10 pack-years was associated with -0.73% (95% CI -0.90% to -0.56%) decrement in the forced expiratory volume in 1 s to forced vital capacity (FEV1 to FVC) and a 0.23% (95% CI 0.08% to 0.38%) increase in per cent emphysema. There was no evidence that relationships of pack-years to the FEV1 to FVC, airflow obstruction and per cent emphysema varied by genetic ancestry (all p>0.10), self-reported race/ethnicity (all p>0.10) or, among African-Americans, African ancestry. There were small differences in relationships of pack-years to the FEV1 among male Chinese-Americans and to the FEV1 to FVC ratio with African and Native American ancestry among male Hispanics only.
  
  
  CONCLUSIONS
  In this large cohort, there was little to no evidence that the associations of smoking to lung function and per cent emphysema differed by genetic ancestry or self-reported race/ethnicity.
authors.affiliation: Department of Medicine, Columbia University Medical Center, New York, NY.
authors.forename: Rhea
authors.initials: R
authors.lastname: Powell
authors.affiliation: Department of Medicine, Columbia University Medical Center, New York, NY.
authors.forename: Duncan
authors.initials: D
authors.lastname: Davidson
authors.affiliation: Department of Biostatistical Sciences, Division of Public Health Sciences, Wake Forest University Health Sciences, Winston-Salem, NC.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Divers
authors.affiliation: Center for Public Health Genomics, University of Virginia, Charlottesville, VA.
authors.forename: Ani
authors.initials: A
authors.lastname: Manichaikul
authors.affiliation: Department of Radiology, Division of Radiological Sciences, Wake-Forest University, Winston-Salem, NC.
authors.forename: J Jeffrey
authors.initials: JJ
authors.lastname: Carr
authors.affiliation: Department of Radiology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA.
authors.forename: Robert
authors.initials: R
authors.lastname: Detrano
authors.affiliation: Department of Radiology, University of Iowa, Iowa City, IA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Hoffman
authors.affiliation: Department of Medicine, Columbia University Medical Center, New York, NY.
authors.forename: Rui
authors.initials: R
authors.lastname: Jiang
authors.affiliation: Department of Biostatistics, University of Washington, Seattle, WA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Kronmal
authors.affiliation: Department of Preventative Medicine, Northwestern University Medical School, Chicago, IL.
authors.forename: Kiang
authors.initials: K
authors.lastname: Liu
authors.affiliation: Department of Medicine, Johns Hopkins University, Baltimore, MD.
authors.forename: Naresh M
authors.initials: NM
authors.lastname: Punjabi
authors.affiliation: Division of Epidemiology and Biostatistics, University of Arizona, Tucson, AZ.
authors.forename: Eyal
authors.initials: E
authors.lastname: Shahar
authors.affiliation: Department of Medicine, University of California at Los Angeles, Los Angeles, CA.
authors.forename: Karol E
authors.initials: KE
authors.lastname: Watson
authors.affiliation: Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA.
authors.forename: Jerome I
authors.initials: JI
authors.lastname: Rotter
authors.affiliation: Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA.
authors.forename: Kent D
authors.initials: KD
authors.lastname: Taylor
authors.affiliation: Center for Public Health Genomics, University of Virginia, Charlottesville, VA.
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Rich
authors.affiliation: Department of Medicine, Columbia University Medical Center, New York, NY.|Department of Epidemiology, Columbia University Medical Center, New York, NY.
authors.forename: R Graham
authors.initials: RG
authors.lastname: Barr
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005006:Ethnicity / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D011656:Pulmonary Emphysema / Q000208:ethnology / Q000235:genetics* / Q000503:physiopathology; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects / Q000208:ethnology* / Q000235:genetics; D013147:Spirometry; D014481:United States / Q000453:epidemiology; D014797:Vital Capacity / Q000502:physiology*
keywords: COPD epidemiology; Emphysema; Tobacco and the lung