[1] Univ N Carolina, Dept Hlth Behav, Chapel Hill, NC 27599 USA
[2] Univ N Carolina, Cecil G Sheps Ctr Hlth Serv Res, Chapel Hill, NC 27599 USA
[3] Univ N Carolina, Dept Epidemiol, Chapel Hill, NC USA
[4] Univ N Carolina, Ctr Hlth Promot & Dis Prevent, Chapel Hill, NC USA
[5] Family Resource Ctr South Atlantic, Raleigh, NC USA
[6] Parent Advocates Adult Children Intellectual & De, Chapel Hill, NC USA
[7] Univ N Carolina, Dept Genet, Chapel Hill, NC USA
[8] Univ N Carolina, Sch Social Work, Family Support Program, Chapel Hill, NC USA
[9] Wake Cty Sickle Cell Support Grp, Raleigh, NC USA
[10] Univ N Carolina, Dept Social Med, Chapel Hill, NC USA
[11] Northwestern Univ, Dept Med Social Sci, Feinberg Sch Med, Chicago, IL 60611 USA
[12] Northwestern Univ, Robert H Lurie Comprehens Canc Ctr, Chicago, IL 60611 USA