[1] UNIV MICHIGAN, DEPT HUMAN GENET, ANN ARBOR, MI 48109 USA
[2] UNIV MICHIGAN, HOWARD HUGHES MED INST, ANN ARBOR, MI 48109 USA
[3] WASHINGTON UNIV, SCH MED, CTR GENET MED, ST LOUIS, MO 63110 USA
[4] UNIV ROCHESTER, MED CTR, DEPT PEDIAT GENET, ROCHESTER, NY 14642 USA