engleski

Cytomorphologic, immunologic and cytogenetic analysis in two children with Down's syndrome and ALL

Trisomy 21 is the most common autosomal anomaly with an incidence of 1 in 700 births. Down's syndrome (DS) patients present a wide spectrum of developmental abnormalities and have an incresed risk of acute leukemia. Acute leukemias are 20 time more frequent in children with trisomy 21 than in children with normal constitutional karyotype. Biological significance of this association is unclear. Cytogenetic analysis of acquired chromosome aberrations in children with DS and acute leukemia are limited. In this report we describe two patients with DS and acute lymphoblatic leukemia. The analysis of acquired chromosomal abnormalities was performed at diagnosis on slides obtained by 24-hour peripheral blood culture without mitogenic stimlation. Chromosome identification was carried out using the G- and C-banding method. Hyperdiploid modal karyotype with gain of chromosome 14 and 21, and deletion of the long arm of chromosome 6 were observed in child with T-cell ALL-L1. Interstitial deletion of chromosome 13, del(13)(q12q14) and deletion of the long arm chromosome 9 were identified in a girl with B-cell ALL-L2. Del(13) is interesting finding since is rare in hematologic malignancies and involves the locus of retinoblastoma gene and locus of DBM tumor supressor gene. Hansen et al. (1990) and Lui et al. (1994) suggested that inactivation of Rb gene represents an important event in leukemogenesis, while Brown et al. (1993) supose that inactivation of DBM is important in the evolution of B-cell malignancies. Further cytogenetic and molecular studies are necessary to clarify the role of the del(13), Rb and DBM genes in the etiology and clinical course of the disease.

cytology; immunology; cytogenetics; Down syndrome; ALL

DOI: 10.1002/pbc.20588