[1] Univ Oxford, Div Med Sci, Dept Physiol Anat & Genet, Oxford OX1 2JD, England
[2] Univ Cape Town, Fac Hlth Sci, Dept Pathol, Div Human Genet, ZA-7700 Rondebosch, South Africa
[3] Univ Cape Town, Fac Hlth Sci, Dept Med, Div Neurol, ZA-7700 Rondebosch, South Africa
[4] Council Sci & Ind Res CSIR Biosci, Synthet Biol ERA, Gene Express & Biophys Grp, Pretoria, South Africa
[5] Univ Cape Town, Fac Hlth Sci, Dept Human Biol, Div Cell Biol, ZA-7700 Rondebosch, South Africa
[6] Univ Cape Town, Fac Hlth Sci, Inst Infect Dis & Mol Med, ZA-7700 Rondebosch, South Africa