[1] Univ Antwerp, Dept Med Genet, B-2610 Antwerp, Belgium
[2] Univ Antwerp Hosp, Dept Med Genet, Antwerp, Belgium
[3] Univ Hosp Brussels, Dept Med Genet, Brussels, Belgium
[4] Univ Hosp Brussels, Dept Rheumatol, Brussels, Belgium
[5] Inst Pathol & Genet, Ctr Human Genet, Loverval, Belgium
[6] Univ Edinburgh, Rheumat Dis Unit, Edinburgh, Midlothian, Scotland
[7] Hosp Clin Barcelona, Dept Rheumatol, E-08036 Barcelona, Spain
[8] Univ Turin, Dept Genet Biol & Biochem, Turin, Italy