[1] UNIV HELSINKI, DEPT MED GENET, SF-00100 HELSINKI 10, FINLAND
[2] NIMH, CTR CLIN, BETHESDA, MD 20205 USA
[3] MASSACHUSETTS GEN HOSP, NEUROGENET LAB NEUROL, BOSTON, MA 02114 USA
[4] HARVARD UNIV, SCH MED, DEPT EPIDEMIOL & PUBL HLTH, BOSTON, MA 02115 USA
[5] HARVARD UNIV, SCH MED, NEUROSCI PROGRAM, BOSTON, MA 02115 USA
[6] HARVARD UNIV, SCH MED, DEPT NEUROL, BOSTON, MA 02115 USA
[7] MASSACHUSETTS EYE & EAR HOSP, RETINA ASSOCIATES & EYE RES INST, BOSTON, MA 02114 USA