Genetic ancestry-smoking interactions and lung function in African Americans: a cohort study.
BACKGROUND
Smoking tobacco reduces lung function. African Americans have both lower lung function and decreased metabolism of tobacco smoke compared to European Americans. African ancestry is also associated with lower pulmonary function in African Americans. We aimed to determine whether African ancestry modifies the association between smoking and lung function and its rate of decline in African Americans.


RESULTS
We evaluated a prospective ongoing cohort of 1,281 African Americans participating in the Health, Aging, and Body Composition (Health ABC) Study initiated in 1997. We also examined an ongoing prospective cohort initiated in 1985 of 1,223 African Americans in the Coronary Artery Disease in Young Adults (CARDIA) Study. Pulmonary function and tobacco smoking exposure were measured at baseline and repeatedly over the follow-up period. Individual genetic ancestry proportions were estimated using ancestry informative markers selected to distinguish European and West African ancestry. African Americans with a high proportion of African ancestry had lower baseline forced expiratory volume in one second (FEV₁) per pack-year of smoking (-5.7 ml FEV₁/ smoking pack-year) compared with smokers with lower African ancestry (-4.6 ml in FEV₁/ smoking pack-year) (interaction P value  = 0.17). Longitudinal analyses revealed a suggestive interaction between smoking, and African ancestry on the rate of FEV(1) decline in Health ABC and independently replicated in CARDIA.


CONCLUSIONS
African American individuals with a high proportion of African ancestry are at greater risk for losing lung function while smoking.
Division of Epidemiology, Department of Thoracic Surgery, Vanderbilt University, Nashville, Tennessee, United States of America. melinda.aldrich@vanderbilt.edu
Melinda C
MC
Aldrich
Rajesh
R
Kumar
Laura A
LA
Colangelo
L Keoki
LK
Williams
Saunak
S
Sen
Stephen B
SB
Kritchevsky
Bernd
B
Meibohm
Joshua
J
Galanter
Donglei
D
Hu
Christopher R
CR
Gignoux
Yongmei
Y
Liu
Tamara B
TB
Harris
Elad
E
Ziv
Joseph
J
Zmuda
Melissa
M
Garcia
Tennille S
TS
Leak
Marilyn G
MG
Foreman
Lewis J
LJ
Smith
Myriam
M
Fornage
Kiang
K
Liu
Esteban G
EG
Burchard
D000293:Adolescent; D000328:Adult; D001741:Black or African American; D000368:Aged; D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000235:genetics / Q000503:physiopathology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008168:Lung / Q000473:pathology*; D008171:Lung Diseases / Q000208:ethnology / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D008957:Models, Genetic; D011446:Prospective Studies; D012129:Respiratory Function Tests; D012306:Risk; D012907:Smoking / Q000503:physiopathology