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- Title
Characterization of a new BLM mutation associated with a topoisomerase II alpha defect in a patient with Bloom's syndrome.
- Authors
Foucault, F; Vaury, C; Barakat, A; Thibout, D; Planchon, P; Jaulin, C; Praz, F; Amor-Guéret, M
- Abstract
Bloom's syndrome (BS), a human recessive disorder associated with an increased risk of malignancy, arises through mutations in both alleles of the BLM gene, which was recently identified as a member of the RecQ helicase family. BS cells are characterized by an increased rate of sister chromatid exchange (SCE). However, a subpopulation of lymphocytes exhibiting a normal level of SCE is observed in some patients. It has been proposed that reversion to a low-SCE phenotype involves an intragenic crossing over between the paternal and maternal BLM alleles, generating a wild-type allele. In this study we characterize a new BLM mutation in a BS patient leading to the replacement, in the C-terminal region of Blm, of a highly conserved cysteine by a phenylalanine in codon 1036. Moreover, our data show that this patient also inherited a BLM allele carrying a mutation affecting its expression and that a somatic intragenic crossing over was involved in reversion to the low-SCE phenotype. Further, we show that both topoisomerase II alpha mRNA and protein levels are decreased in the high-SCE cells derived from this patient, whereas they are normal in the corresponding low-SCE cells. Altogether, our data led us to propose that besides its putative helicase activity, Blm could be involved in transcription regulation.
- Publication
Human molecular genetics, 1997, Vol 6, Issue 9, p1427
- ISSN
0964-6906
- Publication type
Journal Article
- DOI
10.1093/hmg/6.9.1427