[1] Univ Manchester, Acad Unit Clin Genet, Manchester M13 9PL, Lancs, England
[2] Cent Manchestr & Manchester Childrens Univ Hosp, Dept Med Genet, Manchester, Lancs, England
[3] Univ Manchester, ARC Epidemiol Unit, Manchester M13 9PL, Lancs, England
[4] Cent Manchester & Manchester Childrens Univ Hosp, NHS Trust, Rheumat Res Ctr, Manchester, Lancs, England