Questionnaires are sent to next of kin that include a combination of Audit-C screening questions and DSM-IV diagnostic criteria to determine classification of either substance abuse and/or dependence. Seven or more criteria over a 12-month period were required for a ‘dependence’ diagnosis, whereas those that met four or more diagnostic criteria within a 12-month period would receive the ‘abuse’ diagnosis. The alcohol-use phenotype data available are outlined in Table 2.
