[1] ST BARTHOLOMEWS MED COLL,DEPT BIOCHEM,LONDON EC1,ENGLAND
[2] UNIV LONDON,DEPT NEUROL,INST PSYCHIAT,PARKINSONS DIS RES CTR,LONDON SE5 8AF,ENGLAND
[3] UNIV LONDON KINGS COLL HOSP,SCH MED,LONDON SE5 8RX,ENGLAND
[4] UNIV LONDON,DEPT CLIN NEUROL,INST NEUROL,LONDON WC1,ENGLAND