Over this 30 month time period, DNA and clinical information were collected from 2/3 of the members of the average pedigree from which any member came for an appointment. More complete sampling was obtained from smaller than from larger pedigrees. Of the 79 pedigrees for which DNA and clinical information were obtained, fifty-four had 2 members, 15 had 3 members, 7 had 4 members and 3 had 5 members. By the end of this period, DNA and clinical information was successfully collected from 2.5 members of the average pedigree. 14 of these pedigrees contained same-gender and 15 opposite-gender sibs within 5 years of the age of the proband who were discordant for drug abuse phenotype. 18 sibs were within 5 years of age of the proband and concordant for substance abuse phenotype. Thirteen sibs were more than 5 years different in age from the probands and discordant for phenotype, while 4 were concordant.
