title: Transient myeloproliferative disorder in a Down's neonate with rearranged T-cell receptor beta gene and evidence of in vivo maturation demonstrated by dual-colour flow cytometric DNA ploidy analysis.
abstract: Neonates with Down's syndrome may develop a transient myeloproliferative disorder (TMPD) which on presentation is indistinguishable from acute leukemia, with the difference manifest only on follow-up. The clinical course is one of spontaneous remission in TMPD and relentless progression in leukemia. We describe a Down's neonate presenting with hyperleucocytosis and circulating blasts which were positive for CD34, myeloid (CD33), megakaryocytic (CD41, CD42b, CD61), and T-lineage (CD3, CD7), but not B-lineage, associated antigens. Clonal rearrangement of the T-cell receptor beta (TCR beta) gene was found, with the immunoglobulin heavy chain gene in germline configuration, showing the disease to be a clonal proliferation of a multipotential stem cell involving the myeloid and T lineages. Dual-colour flow cytometric DNA ploidy analysis of CD41 positive blasts showed initially a predominant 2N population, but polyploidization to 6N and 8N cells was found on follow-up, concomitant with a progressive decrease in circulating blasts, suggesting maturation of the abnormal clone and a provisional diagnosis of TMPD. This was shown by the eventual resumption of normal haemopoiesis with the disappearance of blasts and the clonally rearranged TCR beta gene.
authors.affiliation: Haematology Section, University Department of Pathology, Queen Mary Hospital, Hong Kong.
authors.forename: Y L
authors.initials: YL
authors.lastname: Kwong
authors.forename: G
authors.initials: G
authors.lastname: Cheng
authors.forename: T S
authors.initials: TS
authors.lastname: Tang
authors.forename: E P
authors.initials: EP
authors.lastname: Robertson
authors.forename: C P
authors.initials: CP
authors.lastname: Lee
authors.forename: L C
authors.initials: LC
authors.lastname: Chan
mesh_terms: D001853:Bone Marrow / Q000737:chemistry / Q000502:physiology; D004247:DNA / Q000235:genetics*; D004314:Down Syndrome / Q000097:blood / Q000150:complications* / Q000235:genetics*; D005434:Flow Cytometry / Q000379:methods; D015321:Gene Rearrangement / Q000235:genetics; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor / Q000235:genetics*; D005803:Genes, Immunoglobulin / Q000235:genetics; D006801:Humans; D016130:Immunophenotyping; D007231:Infant, Newborn; D007621:Karyotyping; D007964:Leukocytosis / Q000097:blood; D008297:Male; D009196:Myeloproliferative Disorders / Q000150:complications* / Q000175:diagnosis / Q000235:genetics*; D011003:Ploidies
chemical_list: D004247:DNA