title: Genetic and environmental influences on forced expiratory volume in African Americans: the Carolina African-American Twin Study of Aging.
abstract: OBJECTIVE
  Previous research found measures of pulmonary functioning to be strong predictors of cognitive functioning and mortality; however, there is considerable individual variability in performance on these measures. In the present analyses, the relative contribution of genetic and environmental influences to variability in average peak expiratory flow rate (APEFR) are examined in a sample of adult African-American twins.
  
  
  METHODS
  Birth records from North Carolina Register of Deeds offices were used to identify participants for the Carolina African-American Twin Study of Aging (CAATSA). Participants completed an in-person interview, which included measures of health status, cognition, and psychosocial measures.
  
  
  METHODS
  Data for the analysis come from 200 pairs of same sex twins (97 identical pairs, and 113 fraternal), with a mean age = 46.9 years (SD = 13.9), and with 39% of the sample being men.
  
  
  RESULTS
  Phenotypic correlations between APEFR, age, gender, height, and cigarette consumption (measured in pack years), were all significant, ranging from -.63 to .43. After the affects of age, gender, height, and pack years were partialled out of APEFR, quantitative genetic analyses were conducted on the residuals. Model fitting demonstrated that variance in APEFR was accounted for by shared environmental effects (30%), genetic effects (14%), and non-shared environmental effects (56%).
  
  
  CONCLUSIONS
  These results are discussed in relation to previous research conducted in other countries, and the importance of a complex systems approach to explanations of the impact of genes on central indices of health, such as APEFR.
authors.affiliation: Department of Biobehavioral Health, The Pennsylvania State University, 315 E Henderson, University Park, PA 16802, USA. kew5@psu.edu
authors.forename: Keith E
authors.initials: KE
authors.lastname: Whitfield
authors.forename: Sebrina A
authors.initials: SA
authors.lastname: Wiggins
authors.forename: Rhonda
authors.initials: R
authors.lastname: Belue
authors.forename: Dwayne T
authors.initials: DT
authors.lastname: Brandon
mesh_terms: D000328:Adult; D001741:Black or African American / Q000235:genetics*; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000235:genetics* / Q000502:physiology; D004777:Environment; D005260:Female; D005541:Forced Expiratory Volume / Q000235:genetics* / Q000502:physiology; D006304:Health Status; D006801:Humans; D007407:Interviews as Topic; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D010366:Peak Expiratory Flow Rate / Q000235:genetics* / Q000502:physiology; D012042:Registries; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects / Q000208:ethnology