RESUMO
Twenty new cases of acute lymphoblastic leukemia (ALL) with the dicentric chromosome dic(9;20)(p1113;q11) are presented. This chromosomal abnormality is difficult to identify from G-banding alone. It masquerades as monosomy 20 and is only accurately identified by fluorescence in situ hybridization (FISH). Monosomy 20 was found in 59/2790 patients with successful karyotypes entered to the Leukaemia Research Fund/UK Cancer Cytogenetics Group Karyotype Database in ALL (LRF/UKCCG Karyotype Database). FISH revealed dic(9;20) in 20/25 cases with available material. Extra copies of chromosome 21 were found in 8 of the 20 cases. Patients were 14 females and six males, aged 1-32 years (median 4 years), with leukocyte counts of 2-536 (median 23) x 109/l and immunophenotypes of common or pre-B ALL (17 cases), T-ALL (one case) or unknown (two cases). Four patients relapsed at 2, 22, 28 and 47 months and two died at 49 and 63 months (median follow-up 37 months). FISH studies on the remaining five patients showed one with monosomy 20 and four with other rearrangements of the chromosome. This study has increased the number of reported cases of dic(9;20) from 17 to 37. It has identified dic(9;20) in one case of T-ALL and shows an association of this translocation with trisomy 21.
Assuntos
Cromossomos Humanos Par 20/genética , Cromossomos Humanos Par 9/genética , Monossomia , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Translocação Genética , Adolescente , Adulto , Criança , Pré-Escolar , Intervalo Livre de Doença , Feminino , Humanos , Imunofenotipagem , Hibridização in Situ Fluorescente , Lactente , Cariotipagem , Masculino , Pessoa de Meia-Idade , Leucemia-Linfoma Linfoblástico de Células Precursoras/mortalidade , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Análise de SobrevidaRESUMO
We present a 34-year-old man with an unbalanced translocation between the long arms of chromosome 4 and chromosome 11. He had manifestations of monosomy 11(q23)--minor facial anomalies, abnormal head shape, cryptorchidism; trisomy 4(q32)--hirsutism, renal disease; and manifestations attributable to both imbalances--heart disease, musculoskeletal anomalies, and mental retardation. FISH studies showed that the chromosome 11q23.3 translocation breakpoint was distal to the rare folate sensitive fragile site (FRA11B). The patient is the oldest reported with both imbalance of 4q+ and 11q-.