title: T-cell acute lymphoblastic leukaemia with late developing Philadelphia chromosome.
abstract: A case of childhood T-cell acute lymphoblastic leukaemia (ALL) is presented in which the only chromosome abnormality at diagnosis was a deletion of part of the short arm of one chromosome 9 (9p-). Cytogenetic studies at relapse showed, in addition to 9p-, a partial deletion of the long arm of one chromosome 6 (6q-) and the Philadelphia chromosome (Ph1) produced as a result of the classical translocation t(9q+;22q-). All metaphases from haemopoietic colonies grown from a cryopreserved specimen of this patient's marrow at relapse were normal, in contrast to haemopoietic colonies cultured from patients with chronic myelogenous leukaemia (CML) which contained the Ph1. A hypothesis which incorporates T-cell ALL with late development of the Ph1 into the overall family of Ph1 positive diseases is suggested.
mesh_terms: D001853:Bone Marrow / Q000648:ultrastructure; D002675:Child, Preschool; D002869:Chromosome Aberrations / Q000235:genetics*; D002872:Chromosome Deletion; D025063:Chromosome Disorders; D002904:Chromosomes, Human, 21-22 and Y / Q000648:ultrastructure*; D002906:Chromosomes, Human, 6-12 and X / Q000648:ultrastructure; D006801:Humans; D007621:Karyotyping; D007945:Leukemia, Lymphoid / Q000235:genetics*; D008297:Male; D013601:T-Lymphocytes; D013997:Time Factors; D014178:Translocation, Genetic