[1] Baylor Coll Med, Dept Mol & Human Genet, Houston, TX 77030 USA
[2] Baylor Coll Med, Dept Pediat, Houston, TX 77030 USA
[3] Texas Childrens Hosp, Houston, TX 77030 USA
[4] McMaster Univ, Dept Pathol & Mol Med, Hamilton, ON, Canada
[5] McMaster Univ, Dept Med, Hamilton, ON, Canada
[6] McMaster Univ, Dept Pediat, Hamilton, ON, Canada
[7] Johns Hopkins Univ, Baltimore, MD USA
[8] Kennedy Krieger Inst, Baltimore, MD USA
[9] State Univ Ghent Hosp, Dept Med Genet, B-9000 Ghent, Belgium