title: Pattern of chromosome involvement in childhood hyperdiploid pre-B-cell acute lymhoblastic leukemia cases from India.
abstract: BACKGROUND
  Hyperdiploid pre-B-cell acute lymhoblastic leukemia (pre-B-ALL) is a common form of childhood leukemia with very good prognosis with present day chemotherapy. However, the chromosomal composition of the hyperdiploidy has not been extensively studied and possible mechanism for this pathology remains so far conjectural.
  
  
  OBJECTIVE
  To analyze the pattern of chromosome involvement in a cohort of childhood hyperdiploid pre-B-ALL from India and from this pattern to develop an understanding on the causation of such pathology. Whether such patients also carry translocations and FLT3 mutations in addition to their hyperdiploid karyotype.
  
  
  METHODS
  One hundred and twenty-six childhood pre-B-ALL patients were studied. Bone marrow aspirate of these patients were evacuated for morphology, FAB classification, immunophenotyping and both conventional and molecular cytogenetics.
  
  
  RESULTS
  Of 126 patients with pre-B-ALL (age 2-15 years), 90 patients with abnormal karyotype showed 50 with hyperdiploid karyotype (50/90 i.e. 55.5%). Chromosomes 9, 10, 14, 17, 18, 20 and 21 were more often involved in hyperdiploidy. Chromosome 21 duplication was present in 92% of the cases. Chromosomes 5, 15, 16, 17 and Y were less often involved (18-20%) in hyperdiploidy. About 44% of patients with hyperdiploidy had additional karyotypic abnormality of which TEL-AML1 was predominant (24%). Chromosome loss was rare and accounted for 20% of the cases only. We did not find any FLT3 mutation in our patients.
  
  
  CONCLUSIONS
  In this study, the pattern of chromosome involvement in hyperdiploid karyotype of ALL patients is same as other studies except some chromosomes like 1, 6, 11, 12, 19 and 22 have some more frequent involvement than other studies. This study also showed the occurrence of TEL/AML1 fusion is more (19.8%) than other reports from India.
authors: Department of Cytogenetics and Molecular Genetics, National Institute of Immunohaematology, KEM Hospital, Mumbai, Maharashtra, India.
authors: Lily S
authors: LS
authors: Kerketta
authors: Department of Cytogenetics and Molecular Genetics, National Institute of Immunohaematology, KEM Hospital, Mumbai, Maharashtra, India.
authors: Vundinti
authors: V
authors: Baburao
authors: Department of Cytogenetics and Molecular Genetics, National Institute of Immunohaematology, KEM Hospital, Mumbai, Maharashtra, India.
authors: Kanjaksha
authors: K
authors: Ghosh
keywords: Abnormal mitosis; centrosome pathology; cytogenetics; hyperdiploidy; pre-B acute lymphoblastic leukemia; selective gain of chromosomes; uniparental disomy