For lifetime CD symptoms, data were drawn from wave 1. All of the subjects were assessed using DSM IV criteria. The GADD sample includes only clinical subjects, so the coefficients from the standardization of the DSM IV CD symptoms from the CADD community sample were applied to the GADD sample (i.e. Z scores of GADD subjects were expressed as deviations from the means of the CADD community samples). After standardization, only phenotypic data from subjects between the ages of 10 and 25 were analyzed. The analysis was performed on 1,540 subjects.
