title: First reported case of intrachromosomal cryptic inv dup del Xp in a boy with developmental retardation.
abstract: We report here on a 6-year-old boy referred to the laboratory for karyotyping and SHOX microdeletion testing. The most significant clinical findings in this boy were small stature, Madelung deformity, facial dysmorphism, mild mental retardation and behavioral problems. R-, G- and RTBG-banding chromosome analysis showed a normal male karyotype. Fine molecular characterization, by FISH, of terminal Xp microdeletion revealed an associated partial duplication. Further refinement of the molecular analysis indicated an inverted duplication of the Xp22.31-Xp22.32 (13.7 Mb) region including the STS, VCX-A and KAL1 genes, associated with a terminal Xp deletion Xp22.33-Xpter (3.6 Mb) encompassing the SHOX and ARSE genes. Such rearrangements have been characterized for other chromosomal pairs, but this is the first reported male patient involving the short arm of the X chromosome. Molecular analysis of the maternal and patient's microsatellite markers showed interchromatid mispairing leading to non-allelic homologous recombination to be the most likely mechanism underlying this rearrangement. This case highlights the importance of clinically driven FISH investigations in order to uncover cryptic micro-rearrangements.
authors.affiliation: AP-HP, Hôpital Cochin, Service Histologie Embryologie Cytogénétique, Université Paris-Descartes, Faculté de Médecine, Unité INSERM U709, Paris, France. celine.dupont@jvr.aphp.fr
authors.forename: Celine
authors.initials: C
authors.lastname: Dupont
authors.forename: Aziza
authors.initials: A
authors.lastname: Lebbar
authors.forename: Cecile
authors.initials: C
authors.lastname: Teinturier
authors.forename: Françoise
authors.initials: F
authors.lastname: Baverel
authors.forename: Geraldine
authors.initials: G
authors.lastname: Viot
authors.forename: Dominique
authors.initials: D
authors.lastname: Le Tessier
authors.forename: Jerome
authors.initials: J
authors.lastname: Le Bozec
authors.forename: Laurence
authors.initials: L
authors.lastname: Cuisset
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Dupont
mesh_terms: D002648:Child; D002872:Chromosome Deletion; D007446:Chromosome Inversion; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics*; D005542:Forearm / Q000000981:diagnostic imaging; D020440:Gene Duplication; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008607:Intellectual Disability / Q000235:genetics*; D007621:Karyotyping; D008297:Male; D008957:Models, Genetic; D011859:Radiography