Genomic rearrangements in the CFTR gene: Extensive allelic heterogeneity and diverse mutational mechanisms

Authors

  • Marie-Pierre Audrézet,

    1. INSERM U613, Génétique Moléculaire et Génétique Epidémiologique, Centre Hospitalier Universitaire, Brest, France
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    • Marie-Pierre Audrézet and Jian-Min Chen contributed equally to this work.

  • Jian-Min Chen,

    1. INSERM U613, Génétique Moléculaire et Génétique Epidémiologique, Université de Bretagne Occidentale, and Etablissement Français du Sang–Bretagne, Brest, France
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    • Marie-Pierre Audrézet and Jian-Min Chen contributed equally to this work.

  • Odile Raguénès,

    1. INSERM U613, Génétique Moléculaire et Génétique Epidémiologique, Centre Hospitalier Universitaire, Brest, France
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  • Nadia Chuzhanova,

    1. Department of Computer Science, Cardiff University, Cardiff, UK
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  • Karine Giteau,

    1. INSERM U613, Génétique Moléculaire et Génétique Epidémiologique, Centre Hospitalier Universitaire, Brest, France
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  • Cédric Le Maréchal,

    1. INSERM U613, Génétique Moléculaire et Génétique Epidémiologique, Université de Bretagne Occidentale, and Etablissement Français du Sang–Bretagne, Brest, France
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  • Isabelle Quéré,

    1. INSERM U613, Génétique Moléculaire et Génétique Epidémiologique, Centre Hospitalier Universitaire, Brest, France
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  • David N. Cooper,

    1. Institute of Medical Genetics, University of Wales College of Medicine, Cardiff, UK
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  • Claude Férec

    Corresponding author
    1. INSERM U613, Génétique Moléculaire et Génétique Epidémiologique, Centre Hospitalier Universitaire, Brest, France
    2. INSERM U613, Génétique Moléculaire et Génétique Epidémiologique, Université de Bretagne Occidentale, and Etablissement Français du Sang–Bretagne, Brest, France
    • INSERM U613, Université de Bretagne Occidentale, Etablissement Français du Sang–Bretagne, Centre Hospitalier Universitaire, 46 rue Félix Le Dantec, 29220 Brest Cedex 2, France
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  • Communicated by Garry R. Cutting

  • This work was presented in the Human Genome Variation Society Scientific and Annual General Meeting (Nov. 4, 2003. Los Angeles, CA, USA), the Amercian Society of Human Genetics 53rd Annual Meeting (Nov. 4–8, 2003. Los Angeles, CA, USA), and the 4th International Symposium on Inherited Diseases of the Pancreas (Nov. 7–9, 2003. Chicago, IL, USA).

Abstract

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR/ABCC7). Despite the extensive and enduring efforts of many CF researchers over the past 14 years, up to 30% of disease alleles still remain to be identified in some populations. It has long been suggested that gross genomic rearrangements could account for these unidentified alleles. To date, however, only a few large deletions have been found in the CFTR gene and only three have been fully characterized. Here, we report the first systematic screening of the 27 exons of the CFTR gene for large genomic rearrangements, by means of the quantitative multiplex PCR of short fluorescent fragments (QMPSF). A well-characterized cohort of 39 classical CF patients carrying at least one unidentified allele (after extensive and complete screening of the CFTR gene by both denaturing gradient gel electrophoresis and denaturing high-performance liquid chromatography) participated in this study. Using QMPSF, some 16% of the previously unidentified CF mutant alleles were identified and characterized, including five novel mutations (one large deletion and four indels). The breakpoints of these five mutations were precisely determined, enabling us to explore the underlying mechanisms of mutagenesis. Although non-homologous recombination may be invoked to explain all five complex lesions, each mutation appears to have arisen through a different mechanism. One of the indels was highly unusual in that it involved the insertion of a short 41 bp sequence with partial homology to a retrotranspositionally-competent LINE-1 element. The insertion of this ultra-short LINE-1 element (dubbed a “hyphen element”) may constitute a novel type of mutation associated with human genetic disease. Hum Mutat 23:343–357, 2004 © 2004 Wiley-Liss, Inc.

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