1. Department of Biochemical Genetics, Cyprus Institute of Neurology and Genetics, 1683 Nicosia, Cyprus.
2. Department of Pediatrics, Arch Makarios III Hospital, 1474 Nicosia, Cyprus.
3. Department of Pediatrics, University of Florence, Meyer Children's Hospital, 50132 Florence, Italy.
4. Department of Genetics, St. Jude Children's Research Hospital, Memphis, TN 38105.