[1] Univ Cape Town, IIDMM, ZA-7925 Cape Town, South Africa
[2] Univ Cape Town, Dept Clin Lab Sci, Div Med Virol, ZA-7925 Cape Town, South Africa
[3] Univ Cape Town, Div Human Genet, Fac Hlth Sci, ZA-7925 Cape Town, South Africa
[4] Uppsala Univ, Dept Genet, Uppsala, Sweden
[5] Uppsala Univ, Dept Pathol, Uppsala, Sweden
[6] MRC, Biostat Unit, Cape Town, South Africa
[7] Univ Western Cape, Dept Stat, Fac Nat Sci, ZA-7535 Bellville, South Africa
[8] Univ Cape Town, Sch Publ Hlth & Family Med, ZA-7925 Cape Town, South Africa
[9] Groote Schuur Hosp, Natl Hlth Lab Serv, ZA-7925 Cape Town, South Africa