title: Microduplications at 22q11.21 are associated with non-syndromic classic bladder exstrophy.
abstract: The exstrophy-epispadias complex (EEC) comprises a spectrum of urogenital anomalies in which part or all of the distal urinary tract fails to close. The present study aimed to identify microaberrations characterized by loss or gain of genomic material that contribute to the EEC at a genome-wide level. Molecular karyotyping, utilizing 549,839 single nucleotide polymorphisms (SNPs) with an average spacing of 5.7 kilobases, was performed to screen an initial cohort of 16 patients with non-syndromic EEC. A de novo microduplication involving chromosomal region 22q11.21 was identified in one patient with classic exstrophy of the bladder (CBE). Subsequent multiplex ligation-dependent probe amplification (MLPA) analysis was performed with an MLPA 22q11 kit in a further 50 non-syndromic EEC cases. We identified one CBE patient with an overlapping 22q11.21 duplication in whom the duplication had been transmitted from the unaffected mother. Chromosomal region 22q11 is well known for its susceptibility to genomic rearrangements, and these are associated with various syndromes including the velo-cardio-facial/DiGeorge syndrome (VCFS/DGS), the der(22) syndrome, and the cat-eye syndrome. Duplications in this region result in a wide and variable spectrum of clinical presentations that include features of the VCFS/DGS, while some carriers present with a completely normal phenotype. Our findings extend the phenotypic spectrum of the 22q11.2 duplication syndrome, and indicate that this aberration predisposes to CBE with incomplete penetrance.
authors.affiliation: Institute of Human Genetics, University of Bonn, Bonn, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Draaken
authors.forename: Heiko
authors.initials: H
authors.lastname: Reutter
authors.forename: Charlotte
authors.initials: C
authors.lastname: Schramm
authors.forename: Enrika
authors.initials: E
authors.lastname: Bartels
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Boemers
authors.forename: Anne-Karoline
authors.initials: AK
authors.lastname: Ebert
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rösch
authors.forename: Annette
authors.initials: A
authors.lastname: Schröder
authors.forename: Raimund
authors.initials: R
authors.lastname: Stein
authors.forename: Susanne
authors.initials: S
authors.lastname: Moebus
authors.forename: Dietlinde
authors.initials: D
authors.lastname: Stienen
authors.forename: Per
authors.initials: P
authors.lastname: Hoffmann
authors.forename: Markus M
authors.initials: MM
authors.lastname: Nöthen
authors.forename: Michael
authors.initials: M
authors.lastname: Ludwig
mesh_terms: D000328:Adult; D001746:Bladder Exstrophy / Q000235:genetics*; D002648:Child; D002875:Chromosomes / Q000648:ultrastructure; D002892:Chromosomes, Human, Pair 22; D005260:Female; D020440:Gene Duplication; D020869:Gene Expression Profiling; D020022:Genetic Predisposition to Disease; D006801:Humans; D007621:Karyotyping; D008297:Male; D015336:Molecular Probe Techniques; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide