Figure 1. Description of the stratification protocol used in this study.

The 4 original sub-phenotypes (denoted by four different colors) were further stratified by removal of families containing affected siblings of another sub-phenotype to yield the Gs level subgroups. These subgroups were further divided according to male only or female-containing pedigrees. Due to intra-family heterogeneity in multiplex cases, some families were included in more than one stratified group. Therefore, the sum of individual and family numbers in subgroups exceeds the numbers listed for the original combined cohort (ALL).