[1] UNIV LONDON UNIV COLL, DEPT GENET, LONDON NW1 2HE, ENGLAND
[2] UNIV LONDON UNIV COLL, DEPT BIOMETRY, LONDON NW1 2HE, ENGLAND
[3] WESTERN GEN HOSP, MRC, HUMAN GENET UNIT, EDINBURGH EH4 2XU, MIDLOTHIAN, SCOTLAND
[4] MED FAK WIEN, INST BIOCHEM, VIENNA, AUSTRIA