Classic bladder exstrophy: Frequent 22q11.21 duplications and definition of a 414 kb phenocritical region.
BACKGROUND
Classic bladder exstrophy (CBE) is the most common form of the bladder exstrophy and epispadias complex. Previously, we and others have identified four patients with a duplication of 22q11.21 among a total of 96 unrelated CBE patients.


METHODS
Here, we investigated whether this chromosomal aberration was commonly associated with CBE/bladder exstrophy and epispadias complex in an extended case-control sample. Multiplex ligation-dependent probe amplification and microarray-based analysis were used to identify 22q11.21 duplications in 244 unrelated bladder exstrophy and epispadias complex patients (including 217 CBE patients) and 665 healthy controls.


RESULTS
New duplications of variable size were identified in four CBE patients and one control. Pooling of our previous and present data (eight duplications in 313 CBE patients) yielded a combined odds ratio of 31.86 (95% confidence interval, 4.24-1407.97). Array-based sequence capture and high-throughput targeted re-sequencing established that all breakpoints resided within the low-copy repeats 22A to 22D. Comparison of the eight duplications revealed a 414 kb phenocritical region harboring 12 validated RefSeq genes. Characterization of these 12 candidate genes through whole-mount in situ hybridization of mouse embryos at embryonic day 9.5 suggested that CRKL, THAP7, and LZTR1 are CBE candidate genes.


CONCLUSIONS
Our data suggest that duplication of 22q11.21 increases CBE risk and implicate a phenocritical region in disease formation.
Institute of Human Genetics, University of Bonn, Bonn, Germany; Department of Genomics, Life & Brain Center, University of Bonn, Bonn, Germany.
Markus
M
Draaken
Friederike
F
Baudisch
Bernd
B
Timmermann
Heiner
H
Kuhl
Martin
M
Kerick
Judith
J
Proske
Lars
L
Wittler
Tracie
T
Pennimpede
Anne-Karoline
AK
Ebert
Wolfgang
W
Rösch
Raimund
R
Stein
Enrika
E
Bartels
Catharina
C
von Lowtzow
Thomas M
TM
Boemers
Stefan
S
Herms
John P
JP
Gearhart
Yegappan
Y
Lakshmanan
Christina Clementsson
CC
Kockum
Gundela
G
Holmdahl
Göran
G
Läckgren
Agnetha
A
Nordenskjöld
Simeon A
SA
Boyadjiev
Bernhard G
BG
Herrmann
Markus M
MM
Nöthen
Michael
M
Ludwig
Heiko
H
Reutter
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics*; D000818:Animals; D001746:Bladder Exstrophy / Q000235:genetics* / Q000473:pathology; D016022:Case-Control Studies; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics*; D058674:Chromosome Duplication; D002892:Chromosomes, Human, Pair 22; D004622:Embryo, Mammalian; D004842:Epispadias / Q000235:genetics* / Q000473:pathology; D005260:Female; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics*; D016017:Odds Ratio; D020411:Oligonucleotide Array Sequence Analysis; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics*; D014521:Urethra / Q000002:abnormalities / Q000378:metabolism; D001743:Urinary Bladder / Q000002:abnormalities / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; C082869:CRKL protein; D002868:Chromosomal Proteins, Non-Histone; D009687:Nuclear Proteins; D014157:Transcription Factors
bladder exstrophy and epispadias complex (BEEC); chromosome 22q11.2; classic bladder exstrophy (CBE); copy number variation; duplication