title: Inverted duplications: how many of them are mosaic?
abstract: The best-known situation indissolubly linked to mosaicism is the uniparental disomy where a trisomic or monosomic zygote develops at least one cell line with 46 chromosomes. The mosaicism normal/abnormal cell lines may remain confined to placenta or persist in the embryo. Here, we describe a second situation that might also be indissolubly linked to a mosaic condition or at least to a confined placental mosaicism. We analysed the case of a mosaicism del(8p)/inv dup(8p) found in prenatal diagnosis. We had already demonstrated that the first product of the abnormal meiotic recombination at the basis of the inv dup rearrangements is a dicentric chromosome. Its breakage leads to the formation of a deleted and an inv dup chromosome. Although we had previously assumed that the dicentric underwent a breakage at meiosis II so that the zygote inherited the inv dup chromosome, our findings and those of others indeed indicate that the dicentric may be inherited in the zygote and that it might persist as such in early postzygotic stages, then undergoing different breakages in different cells leading to different abnormal chromosomes, either deleted or duplicated. Selection versus the most viable cell line(s) results either in a confined placental mosaicism with the inv dup cell line as the only one present in the embryo or in children with both the deleted and the inv dup cell lines. Phenotype/karyotype relationships in inv dup rearrangements must also take into account the influence of the other abnormal cell line during embryogenesis.
authors.affiliation: Biologia Generale e Genetica Medica, University of Pavia, Pavia, Italy.
authors.forename: Tiziano
authors.initials: T
authors.lastname: Pramparo
authors.forename: Sabrina
authors.initials: S
authors.lastname: Giglio
authors.forename: Giuliana
authors.initials: G
authors.lastname: Gregato
authors.forename: Manuela
authors.initials: M
authors.lastname: de Gregori
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Patricelli
authors.forename: Roberto
authors.initials: R
authors.lastname: Ciccone
authors.forename: Susi
authors.initials: S
authors.lastname: Scappaticci
authors.forename: Gaetano
authors.initials: G
authors.lastname: Mannino
authors.forename: Claudio
authors.initials: C
authors.lastname: Lombardi
authors.forename: Barbara
authors.initials: B
authors.lastname: Pirola
authors.forename: Roberto
authors.initials: R
authors.lastname: Giorda
authors.forename: Mariano
authors.initials: M
authors.lastname: Rocchi
authors.forename: Orsetta
authors.initials: O
authors.lastname: Zuffardi
mesh_terms: D037881:Aborted Fetus; D015193:Chorionic Villi Sampling; D002871:Chromosome Banding; D002872:Chromosome Deletion; D007446:Chromosome Inversion / Q000235:genetics*; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics*; D005819:Genetic Markers; D006330:Heart Defects, Congenital / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D009030:Mosaicism
chemical_list: D005819:Genetic Markers