A novel molecular variant of the chimeric NPM-ALK transcript in Ki-1 positive large cell lymphoma

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · American Journal of Human Genetics

OSTI ID:133532

Ladanyi, M ^[1]

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1. Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

The breakpoints of the t(2;5)(p23;q35), reported to be present in 30-40% of Ki-1 positive large cell lymphoma (Ki-1 LCL), have recently been cloned. They involve a novel tyrosine kinase gene, ALK, at 2p23 and the nucleophosmin gene, NPM, at 5q35. Reverse transcriptase polymerase chain reaction (RT-PCR) using NPM and ALK primers detects a consistent fusion product in Ki-1 cases with the translocation. We performed NPM-ALK RT-PCR on 16 cases of Ki-1 LCL, of which 13 had informative cytogenetics. Amplifiable template was confirmed in all samples by RT-PCR using {beta}-actin primers. Ten cases showed the expected 177 base pair (bp) RT-PCR product indicative of the translocation, including all 6 cases with cytogenetic evidence of the t(2;5) and 3 cases without 5q35 abnormalities. One additional case, which had uninformative cytogenetics, showed only a novel 144 bp RT-PCR product. Sequencing of this PCR product showed an in-frame junction of NPM to ALK, 20 bp distal to the usual NPM junction site and 53 bp distal to usual ALK junction site. The predicted chimeric protein is thus shorter by 11 amino acids, but the putative ALK catalytic domain remains intact. This case was a histologically typical anaplastic Ki-1 LCL which showed a clonal rearrangement of the T-cell receptor {beta} gene. The functional significance of this molecular variant and its relation to the exon structure of both genes require further study. The overall incidence of the translocation in this series, about 70%, is higher than suspected from cytogenetic analysis alone.

• OSTI ID: 133532
• Report Number(s): CONF-941009--
• Journal Information: American Journal of Human Genetics, Journal Name: American Journal of Human Genetics Journal Issue: Suppl.3 Vol. 55; ISSN AJHGAG; ISSN 0002-9297
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
AMINO ACID SEQUENCE
BIOLOGICAL FUNCTIONS
CHIMERAS
CHROMOSOMAL ABERRATIONS
DNA-CLONING
GENE MUTATIONS
GENES
GENETIC MAPPING
HUMAN CHROMOSOME 2
HUMAN CHROMOSOME 5
LYMPHOMAS
PATIENTS
POLYMERASE CHAIN REACTION
PROTEINS
TRANSCRIPTION