The demographic features of the proband and affected sibling samples are shown in Table 1. The average age of probands was 38.6 years (SD=7.4) and 51% were women. The average age of siblings was 38.9 years (SD=7.5), and 48% were women. The majority of subjects (~85%) were not married (i.e., divorced, separated, or widowed). The self-reported ethnic/racial distribution of the proband sample was 45.9% African-American (AA), 34.7% European-American (EA), 13.8% Hispanic, and 5.6% Native American, Pacific Islander or other minority groups. The sibling sample’s self-reported ethnic/racial distribution was comparable but not identical to that of probands (Table 1). Most participants had either entered or attended but not completed high school, and most (63%) were unemployed, disabled, retired, or a student.
