[1] FREE UNIV AMSTERDAM,INST HUMAN GENET,DEPT GASTROENTEROL,1007 MC AMSTERDAM,NETHERLANDS
[2] FREE UNIV AMSTERDAM,DEPT MED STAT,1007 MC AMSTERDAM,NETHERLANDS
[3] UNIV LEIDEN,MED CTR,DEPT GASTROENTEROL,LEIDEN,NETHERLANDS
[4] SOPHIA HOSP,DEPT INTERNAL MED,ZWOLLE,NETHERLANDS