Initial ascertainment of alcohol-dependent probands (designated Stage I) was performed by screening consecutive admissions at treatment facilities. Probands were assessed with the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA), a comprehensive diagnostic instrument developed for this study and now widely used [18 (
link),19 (
link)]. Extensive histories of substance use and abuse were gathered along with diagnostic information for multiple Axis I disorders and antisocial personality disorder. To be recruited into the COGA study, probands had to meet both the diagnostic criteria for alcohol dependence (by DSM-III-R criteria [20 ] and the criteria for definite alcoholism specified by Feighner et al. [21 (
link)]); thus, the COGA sample is representative of a severely alcohol-dependent population. All first degree relatives of the probands were invited to participate. Children and adolescents in the families were assessed with complementary age-appropriate instruments (C-SSAGA, child and adolescent versions). A set of control families was ascertained to provide normative measures; they were not screened to eliminate those with psychiatric disorders, and are similar to a general population sample. Written informed consent was obtained from all subjects, and the Institutional Review Boards (IRB) of each collaborative site approved all procedures. A more complete description of the recruitment procedures can be found in Begleiter et al. [1 (
link),22 ]. Over 13,000 individuals have been interviewed to date.
A subset of COGA families with at least three alcohol-dependent first degree relatives (designated Stage II) was identified as suitable for a genetic linkage study [1 (
link)]. These families were extended by diagnostic assessment of more distant relatives in branches reached through an affected member. The Stage II families participated in a more comprehensive multi-domain assessment with an electrophysiologic evaluation of event-related potentials (ERP), event-related oscillations (EROs) and resting electroencephalogram (EEG), endophenotypes associated with alcohol dependence [23 (
link),24 ] that are more proximal to genes and may provide measures of the liability underlying a predisposition to alcohol dependence and related disorders.
Edenberg H.J., Bierut L.J., Boyce P., Cao M., Cawley S., Chiles R., Doheny K.F., Hansen M., Hinrichs T., Jones K., Kelleher M., Kennedy G.C., Liu G., Marcus G., McBride C., Murray S.S., Oliphant A., Pettengill J., Porjesz B., Pugh E.W., Rice J.P., Rubano T., Shannon S., Steeke R., Tischfield J.A., Tsai Y.Y., Zhang C, & Begleiter H. (2005). Description of the data from the Collaborative Study on the Genetics of Alcoholism (COGA) and single-nucleotide polymorphism genotyping for Genetic Analysis Workshop 14. BMC Genetics, 6(Suppl 1), S2.