A somatic origin of homologous Robertsonian translocations and isochromosomes
- Univ. of Zurich (Switzerland)
- Univ. of Istanbul (Turkey)
- Universita Cattolica, Rome (Italy)
- Hopital d'Enfants Pellegrin, Bordeaux (France)
- Univ. Hospital of Hradeck Kralove, Hradec Kralove (Czech Republic)
- Escuola Paulista de Medicina, Sao Paulo (Brazil); and others
One t(14q 14q), three t(15q 15q), two t(21q21q), and two t(22q22q) nonmosaic, apparently balanced, de novo Robertsonian translocation cases were investigated with polymorphic markers to establish the origin of the translocated chromosomes. Four cases had results indicative of an isochromosome: one t(14q14q) case with mild mental retardation and maternal uniparental disomy (UPD) for chromosome 14, one t(15q15q) case with the Prader-Willi syndrome and UPD(15), a phenotypically normal carrier of t(22q22q) with maternal UPD(22), and a phenotypically normal t(21q21q) case of paternal UPD(21). All UPD cases showed complete homozygosity throughout the involved chromosome, which is supportive of a postmeiotic origin. In the remaining four cases, maternal and paternal inheritance of the involved chromosome was found, which unambiguously implies a somatic origin. One t(15q15q) female had a child with a ring chromosome 15, which was also of probable postmeiotic origin as recombination between grandparental haplotypes had occurred prior to ring formation. UPD might be expected to result from de novo Robertsonian translocations of meiotic origin; however, all de novo homologous translocation cases, so far reported, with UPD of chromosomes 14, 15, 21, or 22 have been isochromosomes. These data provide the first direct evidence that nonmosaic Robertsonian translocations, as well as isochromosomes, are commonly the result of a mitotic exchange. 75 refs., 1 fig., 4 tabs.
- OSTI ID:
- 6975717
- Journal Information:
- American Journal of Human Genetics; (United States), Vol. 54:2; ISSN 0002-9297
- Country of Publication:
- United States
- Language:
- English
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