Consistent with our prior results (Gelernter et al., 2006; Chan et al., 2011), we identified five distinct subtypes in this sample of subjects participating in genetic studies of CD and OD. When we compared our results with those obtained in a previous analysis of a subset of these data (Chan et al., 2011), we found two groups that were larger and had higher heritability estimates than were obtained previously. Specifically, Groups 4 and 5 consisted of a total 2,115 subjects, or 39% of the total sample, compared to only 984 subjects in two clusters with a high heritability estimate (24% of the total sample) in our previous study (Chan et al., 2011). This improves the potential utility of our approach for gene finding, by increasing the statistical power of studies that employ these subtypes. The groups in our solution were also phenotypically more distinct. For instance, our non-opioid-user group (Group 1) contained no subjects with a lifetime diagnosis of OD, compared with 20% of the lowest opioid-use group in our prior study (Chan et al., 2011). The late-onset group in
