Unexpected complexity at breakpoint junctions in phenotypically normal individuals and mechanisms involved in generating balanced translocations t(1;22)(p36;q13)
- Marzena Gajecka1,2,
- Andrew J. Gentles3,
- Albert Tsai4,
- David Chitayat5,
- Katherine L. Mackay1,
- Caron D. Glotzbach1,
- Michael R. Lieber4, and
- Lisa G. Shaffer1,6
- 1 School of Molecular Biosciences, Washington State University, Spokane, Washington 99202, USA;
- 2 Institute of Human Genetics, Polish Academy of Sciences, Poznan 61-713, Poland;
- 3 School of Medicine, Stanford University, Stanford, California 94305, USA;
- 4 University of Southern California Comprehensive Cancer Center, University of Southern California, Los Angeles, California 90089, USA;
- 5 Prenatal Diagnosis and Medical Genetics, Mount Sinai Hospital, Toronto M5G 1X5, Canada
Abstract
Approximately one in 500 individuals carries a reciprocal translocation. Balanced translocations are usually associated with a normal phenotype unless the translocation breakpoints disrupt a gene(s) or cause a position effect. We investigated breakpoint junctions at the sequence level in phenotypically normal balanced translocation carriers. Eight breakpoint junctions derived from four nonrelated subjects with apparently balanced translocation t(1;22)(p36;q13) were examined. Additions of nucleotides, deletions, duplications, and a triplication identified at the breakpoints demonstrate high complexity at the breakpoint junctions and indicate involvement of multiple mechanisms in the DNA breakage and repair process during translocation formation. Possible detailed nonhomologous end-joining scenarios for t(1;22) cases are presented. We propose that cryptic imbalances in phenotypically normal, balanced translocation carriers may be more common than currently appreciated.
Footnotes
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↵6 Corresponding author.
↵6 E-mail shaffer{at}signaturegenomics.com; fax (509) 474-6839.
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[Supplemental material is available online at www.genome.org.]
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Article published online before print. Article and publication date are at http://www.genome.org/cgi/doi/10.1101/gr.077453.108.
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- Received February 13, 2008.
- Accepted June 17, 2008.
- Copyright © 2008, Cold Spring Harbor Laboratory Press
