title: Recurrent 70.8 Mb 4q22.2q32.3 duplication due to ovarian germinal mosaicism.
abstract: A mosaicism is defined by the presence of two or more populations of cells with different genotypes in one individual. Chromosomal germinal mosaicism occurs in germ cells before the onset of meiosis. Previously, few studies have described germinal mosaicism. In this study, we report on two siblings who carried identical pure and direct interstitial 4q22.2q32.3 duplication. Procedure investigations included complete clinical description, conventional cytogenetic analysis, fluorescence in situ hybridization (FISH), comparative genomic hybridization (CGH) array experiments and microsatellite study searching for parental origin of the duplication. Microarray CGH and further FISH experiments with BAC clones showed the same 70.8 Mb direct duplication, dup(4)(q22.2q32.3). Molecular studies of the 4q duplication were consistent with maternal origin associated with mitotic or meiotic rearrangements. This structural chromosomal aberration was associated in both cases with increased nuchal translucency, growth retardation and dysmorphy. Cardiopathy and lung malformations were only evident in the first case. These clinical manifestations are similar to those previously reported in previous studies involving pure 4q trisomy of the same region, except for thumb and renal abnormalities that were not obvious in the presented cases. The amplified region included genes involved in neurological development (NEUROG2, MAB21L2, PCDH10/18 and GRIA2). The recurrent 4q duplication in these siblings is consistent with a maternal ovarian germinal mosaicism. This is the first description of germinal mosaicism for a large chromosomal duplication and highlights that genetic counselling for apparently de novo chromosome aberration should be undertaken with care.
authors.affiliation: AP-HP, Histologie, Embryologie et Cytogénétique, Hôpital Antoine Béclère, 157 rue de la Porte de Trivaux, Clamart Cedex, France. lucie.tosca@abc.aphp.fr
authors.forename: Lucie
authors.initials: L
authors.lastname: Tosca
authors.forename: Sophie
authors.initials: S
authors.lastname: Brisset
authors.forename: François M
authors.initials: FM
authors.lastname: Petit
authors.forename: Laure
authors.initials: L
authors.lastname: Lecerf
authors.forename: Ghislaine
authors.initials: G
authors.lastname: Rousseau
authors.forename: Cécile
authors.initials: C
authors.lastname: Bas
authors.forename: Mireille
authors.initials: M
authors.lastname: Laroudie
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Maurin
authors.forename: Sylvie
authors.initials: S
authors.lastname: Tapia
authors.forename: Olivier
authors.initials: O
authors.lastname: Picone
authors.forename: Sophie
authors.initials: S
authors.lastname: Prevot
authors.forename: Michel
authors.initials: M
authors.lastname: Goossens
authors.forename: Philippe
authors.initials: P
authors.lastname: Labrune
authors.forename: Gérard
authors.initials: G
authors.lastname: Tachdjian
mesh_terms: D002675:Child, Preschool; D002869:Chromosome Aberrations; D002894:Chromosomes, Human, Pair 4 / Q000235:genetics*; D020732:Cytogenetic Analysis; D005260:Female; D020440:Gene Duplication; D015321:Gene Rearrangement / Q000235:genetics*; D005817:Genetic Counseling; D006801:Humans; D007621:Karyotyping; D018895:Microsatellite Repeats; D009030:Mosaicism; D010063:Ovum; D035781:Siblings