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Centric fission, centromere‐telomere fusion and isochromosome formation: a possible origin of a de novo 12p trisomy
Author(s) -
Rivera H.,
GarcíaEsquivel L.,
JiménezSáinz M.,
Vaca G.,
Ibarra B.,
Cantú J. M.
Publication year - 1987
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1111/j.1399-0004.1987.tb02831.x
Subject(s) - centromere , isochromosome , telomere , chromosomal translocation , biology , dicentric chromosome , genetics , chromosome , karyotype , microbiology and biotechnology , dna , gene
A 5‐month‐old girl had a typical 12p trisomy syndrome due to a monocentric i(12p) present in a 46‐chromosome complement that also included the translocation of all 12q onto the 8p telomere; i.e., her complex karyotype could be written as 46.XX, – 8,–12,+ der(8),t(8;12)(p23.3;cen), + i(12p). The present concurrence of a whole‐arm q translocation and an i(p) for a single chromocome, along with six previous similar instances involving chromosomes 4, 5 and 9, suggests the following origin for such a special rearrangement: a centric fission in Gl initially yielding two telocentrics; at the next replication, the tel(q) translocates onto a nonhomologous telomere (centromere‐telomere fusion), whereas the tel(p) becomes an i(p). This mechanism can be either meiotic or postzygotic and surmises that the translocated long arm retains a partial centromere, which subsequently is inactivated and loses its staining properties.