Data from the Framingham Heart Study along with clinical exam information from 1948 through 1988 for the original cohort and from 1971 through 1991 for the offspring cohort were provided through Genetics Analysis Workshop 13 (GAW13). On the basis of number of smokers present at each exam, the consistency of the clinical data and interviewing time between the two cohorts, and the potential environmental effect on smoking phenotype included in the Framingham Heart Study data, Exam 12 from 1970 for the original cohort and Exam 1 from 1971 for the offspring cohort were selected and used in this study.
