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Updated: Jul 2, 2026

FISH for Pre-implantation Genetic Diagnosis
Published on: February 23, 2011
Unexpected complexity at breakpoint junctions in phenotypically normal individuals and mechanisms involved in
Marzena Gajecka1, Andrew J Gentles, Albert Tsai
1School of Molecular Biosciences, Washington State University, Spokane, Washington 99202, USA.
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.
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