[1] Wayne State Univ, Detroit, MI USA
[2] C Besta Neurol Inst, Milan, Italy
[3] Childrens Hosp Philadelphia, Philadelphia, PA 19104 USA
[4] Childrens Hosp Westmead, Sydney, NSW, Australia
[5] Univ Penn, Philadelphia, PA 19104 USA
[6] Univ Rochester, Rochester, NY USA
[7] Natl Hosp Neurol & Neurosurg, London WC1N 3BG, England