Characterisation of a non-recurrent familial translocation t(7;9)(q11.23;p24.3) points to a recurrent involvement of the Williams-Beuren syndrome region in chromosomal rearrangements.
Recurrent and non-recurrent chromosomal rearrangements seem to reflect susceptibility to DNA rearrangements due to the presence of recombinogenic motifs in at least one partner chromosomal region. While specific genomic motifs such as AT-rich repeats, fragile sites and Alu repeats are often found in recurrent translocations, the molecular mechanisms underlying non-recurrent chromosomal rearrangements remain largely unknown. Here, we map the breakpoint region of a non-recurrent translocation, t(7;9)(q11.23;p24.3), present in a healthy woman who inherited the apparently balanced translocation from her mother and transmitted the same rearrangement to two sons-respectively healthy and aborted. Characterisation by a two-step FISH analysis, first with BAC clones and then with small locus-specific probes, restricted the breakpoint intervals to 8-10 kb. Both regions contained specific Alu sequences, which, together with the flanking low copy repeat block Ac in 7q11.23, might stimulate the translocation. We noted that, although the translocation is non-recurrent, 7q11.23 is recurrently involved in different chromosomal rearrangements, supporting the hypothesis that the 7q11.23 genomic structure is prone to recombination events.
Portera
Giorgio
G
Department of Biology and Genetics, Medical Faculty, University of Milan, Milan, Italy.
Venturin
Marco
M
Department of Biology and Genetics, Medical Faculty, University of Milan, Milan, Italy.
Patrizi
Antonella
A
Department of Biology and Genetics, Medical Faculty, University of Milan, Milan, Italy.
Martinoli
Emanuela
E
Department of Biology and Genetics, Medical Faculty, University of Milan, Milan, Italy.
Riva
Paola
P
Department of Biology and Genetics, Medical Faculty, University of Milan, Milan, Italy.
Dalprà
Leda
L
Department of Neurosciences and Biomedical Technologies, University of Milano Bicocca, Via Cadore 48, 20 052, Monza, Italy. leda.dalpra@unimib.it.
D001483:Base Sequence; D002897:Chromosomes, Human, Pair 7; D002899:Chromosomes, Human, Pair 9; D019295:Computational Biology; D017931:DNA Primers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D014178:Translocation, Genetic; D018980:Williams Syndrome / Q000235:genetics*
D017931:DNA Primers