[1] MRC, CLIN RES CTR, HARROW HA1 3UJ, MIDDX, ENGLAND
[2] INST CHILD HLTH, LONDON WC1N 1EH, ENGLAND
[3] UNIV CONNECTICUT, CTR HLTH, SCH MED, DEPT PEDIAT, FARMINGTON, CT 06032 USA
[4] UNIV ZURICH, INST MED GENET, CH-8006 ZURICH, SWITZERLAND
[5] UNIV ZURICH, DEPT PAEDIAT, CH-8006 ZURICH, SWITZERLAND
[6] UNIV STELLENBOSCH, SCH MED, MRC, CTR MOLEC & CELLULAR BIOL, TYGERBERG 7505, SOUTH AFRICA
[7] NATL HOSP, BLOOD BANK, DIV GENET, REYKJAVIK, ICELAND
[8] NORWEGIAN RADIUM HOSP, INST CANC RES, DEPT GENET, OSLO, NORWAY
[9] FRAMBU HLTH CTR, SIGGERUD, NORWAY