A Palindrome-Mediated Recurrent Translocation with 3:1 Meiotic Nondisjunction: The t(8;22)(q24.13;q11.21)

The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
The American Journal of Human Genetics (Impact Factor: 10.93). 08/2010; 87(2):209-18. DOI: 10.1016/j.ajhg.2010.07.002
Source: PubMed


Palindrome-mediated genomic instability has been associated with chromosomal translocations, including the recurrent t(11;22)(q23;q11). We report a syndrome characterized by extremity anomalies, mild dysmorphia, and intellectual impairment caused by 3:1 meiotic segregation of a previously unrecognized recurrent palindrome-mediated rearrangement, the t(8;22)(q24.13;q11.21). There are at least ten prior reports of this translocation, and nearly identical PATRR8 and PATRR22 breakpoints were validated in several of these published cases. PCR analysis of sperm DNA from healthy males indicates that the t(8;22) arises de novo during gametogenesis in some, but not all, individuals. Furthermore, demonstration that de novo PATRR8-to-PATRR11 translocations occur in sperm suggests that palindrome-mediated translocation is a universal mechanism producing chromosomal rearrangements.


Available from: April Hacker, Aug 24, 2014
A Palindrome-Mediated Recurrent Translocation
with 3:1 Meiotic Nondisjunction:
The t(8;22)(q24.13;q11.21)
Molly B. Sheridan,
Takema Kato,
Chad Haldeman-Englert,
G. Reza Jalali,
Jeff M. Milunsky,
Ying Zou,
Ruediger Klaes,
Georgio Gimelli,
Stefania Gimelli,
Robert M. Gemmill,
Harry A. Drabkin,
April M. Hacker,
Julia Brown,
David Tomkins,
Tamim H. Shaikh,
Hiroki Kurahashi,
Elaine H. Zackai,
and Beverly S. Eman uel
Palindrome-mediated genomic instability has been associated with chromosomal translocations, including the recurrent t(11;22)
(q23;q11). We report a syndrome characterized by extremity anomalies, mild dysmorphia, and intellectual impairment caused by 3:1
meiotic segregation of a previously unrecognized recurrent palindrome-mediated rearrangement, the t(8;22)(q24.13;q11.21). There
are at least ten prior reports of this translocation, and nearly identical PATRR8 and PATRR22 breakpoints were validated in several of
these published cases. PCR analysis of sperm DNA from healthy males indicates that the t(8;22) arises de novo during gametogenesis
in some, but not all, individuals. Furthermore, demonstration that de novo PATRR8-to-PATRR11 translocations occur in sperm suggests
that palindrome-mediated translocation is a universal mechanism producing chromosomal rearrangements.
Approximately one in 600 individuals is the carrier of
a balanced constitutional translocation.
Most balanced-
translocation carriers are healthy and do not come to
medical attention until they experience infertility or the
birth of an abnormal child with an unbalanced form of
the translocation.
The majority of non-Robertsonian
constitutional translocations are unique. Only two translo-
cations, the t(11;22)(q23;q11) and the t(4;8)(pl6;p23),
have been reported to recur de novo multiple times.
Both are identified after meiotic malsegregation that
results in abnormal offspring. The constitutional t(11;22)
segregates 3:1 and has been described as the most common
recurrent non-Robertsonian translocation in humans.
Although t(11;22) balanced-translocation carriers are phe-
notypically normal, males are occasionally subject to infer-
tility, whereas females may experience recurrent preg-
nancy loss. Carriers are often identified after the birth of
unbalanced offspring with the supernumerary der(22)
t(11;22) syndrome (Emanuel syndrome [MIM 609029]).
Unlike the t(11;22), the t(4;8) undergoes 2:2 malsegrega-
tion. Patients who carry the der(4)t(4;8) have Wolf-Hirsch-
horn syndrome (MIM 194190), whereas patients who
carry the der(8)t(4;8) have a different phenotype, which
includes mental retardation.
These two translocations are hypothesized to recur by
distinct mechanisms. The t(4;8) is postulated to be medi-
ated by homologous recombination between olfactory
receptor gene clusters.
Alternatively, the breakpoints
of numerous unrelated t(11;22) cases have been consis-
tently shown to be located within palindromic AT-rich
repeats (PATRRs) on 11q23 and 22q11.
This suggests
that the t(11;22) is caused by the formation of hairpin/
cruciform structures that lead to double-strand DNA breaks
and chromosomal translocation. Interestingly, a t(17;22)
has been identified in two unrelated cases. Similar to the
t(11;22), both of the reported t(17;22)s have been shown
to be mediated by the same PATRR on 22q11.2 and a PATRR
in intron 31 of the NF1 gene.
These translocations
involving the PATRR at 22q11 suggested the possibility
for other PATRR-mediated rearrangements in humans,
given that palindrome-induced genetic instability has
been clearly demonstrated in numerous model organisms,
including bacteria, yeast, and mice.
Indeed, the PATRR on chromosome 22 has been
described as a hotspot for translocation breakpoints.
Recent findings of PATRR-like or palindromic sequences
at the translocation breakpoints of other chromosome 22
partner chromosomes (chromosomes 1p, 4q, and 8q) sup-
port the hypothesis that palindrome-mediated genomic
rearrangement is a pathway for producing chromosomal
The majority of the t(11;22) as well
as the two t(17;22) breakpoints have been localized at
the center of the PATRRs, suggesting that the center of
the palindrome is susceptible to breakage as a prerequisite
Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA;
Division of Molecular Genetics, Institute for Compre-
hensive Medical Science, Fujita Health University, Toyoake, Aichi, 470-1192, Japan;
Wake Forest University School of Medicine, Winston-Salem, NC
27157, USA;
Boston University School of Medicine, Boston, MA 02118, USA;
Mannheim Center for Human Genetics, Mannheim, 68165, Germany;
Laboratorio di Citogenetica, Istituto G. Gaslini, Genova, 16147, Italy;
Department of Genetic Medicine, University Hospitals of Geneva, Geneva,
1211, Switzerland;
Medical University of South Carolina, Charleston, SC 29425, USA;
Department of Pediatrics, University of Colorado, Denver, CO
80045, USA;
University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
DOI 10.1016/j.ajhg.2010.07.002. Ó2010 by The American Society of Human Genetics. All rights reserved.
The American Journal of Human Genetics 87, 209–218, August 13, 2010 209
Page 1
to chromosomal rearrangement. However, until now, the
only translocations involving PATRRs identified more
than once were the t(11;22) and the t(17;22).
In this manuscript, we describe multiple individuals
with balanced and unbalanced forms of the t(8;22)
(q24.13;q11.2). Most have been previously reported, and
one is a new example seen at our institution. However,
this translocation had not previously been recognized as
a recurrent rearrangement with a consistent mechanism.
Interestingly, the 8q breakpoint region is also involved in
a t(3;8) which has been reported to segregate with renal
cell carcinoma in two independent families.
Similar to
the t(11;22), the 8;22 translocation segregates 3:1 to pro-
duce unbalanced karyotypes, and all examples studied
occur at nearly identical breakpoints in PATRRs on 8q and
22q. The reports of at least 12 cases of this rearrangement
and the detection of this translocation in sperm from
chromosomally normal males suggest that it is another
recurrent palindrome-mediated non-Robertsonian translo-
cation. These findings provide additional support for the
role of palindromic sequences in genomic instability.
Material and Methods
Fluorescence In Situ Hybridization
Cytogenetic and fluorescence in situ hybridization (FISH) analyses
were performed on metaphase spreads from peripheral-blood
lymphocyte cultures as described in Gotter et al.,
with the use
of the bacterial artificial chromosome clone RP11–158k1. This
research study was approved by the institutional review board of
the Children’s Hospital of Philadelphia, and written consent was
obtained from all patients or their parents.
Sequence Analysis of t(8;22) Junction Sequences
Genomic DNA was extracted from peripheral blood or lympho-
blast cell lines via previously described methods.
PCR was performed with the use of the primers described in Gotter
et al.
Primer sequences are available in Table S1, available online.
In brief, der(8) products were amplified with the use of the
following primers: primary amplification: 8q24-7F with 22.B2R;
secondary amplification: 8q24-8F with 22.B4R; der(22) product
amplification: primary amplification: 22.B1 and 8q24-7R, sec-
ondary amplification: 22.B3 and 8q24-8R. Samples were subjected
to PCR purification (Qiaquick PCR Purification Kit, QIAGEN) and
sequenced bidirectionally by capillary electrophoresis (ABI3730
Genetic Analyzer, Applied Biosytems). Sequences were analyzed
with the Sequencher analysis program (Gene Codes). Kalign
(Tool for Fast Multiple Protein and Nucleotide Sequence Align-
ment) was used to align the resulting sequences.
Genome-wide SNP Array
Genomic DNA samples were analyzed with the use of the Affyme-
trix SNP 6.0 Array platform according to the manufacturer’s
instructions (Affymetrix). Copy-number data were analyzed with
the Partek Genomics Suite (Partek).
Determination of t(8;22) De Novo Frequency
Anonymous sperm samples were obtained from normal, healthy
volunteers and tested for the der(8)t(8;22) and/or the der(22)
t(8;22) PCR fragment. DNA was extracted from fresh or frozen
semen samples with the Puregene DNA purification kit (QIAGEN)
according to the manufacturer’s instructions. PCR was performed
as above, with the use of 24 100 ng aliquots of each sperm DNA
sample and a 5
fluorescently labeled reverse primer (6-carboxy-
fluorescein). Products were separated by agarose gel electropho-
resis or capillary electrophoresis on an ABI 3730 DNA Analyzer
(Applied Biosystems). Sizes were estimated against an internal
standard (ROX 500, 6-Carboxyl-X-Rhodamine) with GeneMapper
software (Applied Biosystems). The translocation frequency was
calculated via the methods described in Kurahashi et al.
PATRR8 Characterization
Genomic DNA was amplified with primers flanking the PATRR8
(primer sequences are available in Table S1). PCR was performed
with Advantage2 Polymerase (Clontech) or the LA Taq DNA
Polymerase system (Takara). Products were separated by agarose
gel electrophoresis and excised (QIAquick Gel Extraction Kit,
QIAGEN). The purified products were cloned into pCR2.1TOPO
(Invitrogen), and transformed into SURE (Stop Unwanted Rear-
rangement Events) strain E.Coli (Stratagene). Plasmid DNA was
extracted and was sequenced as above.
t(8;11)(q24.1,q23) and t(1;22)(p21.2,q11.2)
Amplification in Sperm DNA
Der(8) and der(11)t(8;11) products were amplified with the use of
the primers described in Gotter et al.
and Kurahashi et al.
was performed with the LA Taq DNA Polymerase system (Takara),
with the use of 250 ng aliquots of each sperm DNA sample. The
resulting products were separated by gel electrophoresis and
sequenced as above. A similar assay was performed for the detec-
tion of t(1;22) junction fragments with the use of the primers
described in Gotter et al.
and listed in Table S1.
Identification of a t(8;22) with Nearly Identical
PATRR Breakpoints
We previously reported a patient with þder(22)t(8;22)
The breakpoints at 8q24.1 and 22q11.2
occur in PATRRs. A second patient with a molecularly
similar supernumerary der(22)t(8;22) was referred to our
attention. Like the father of the first patient, the mother
of this second patient carries what cytogenetically ap-
peared to be a similar t(8;22)(q24.1;q11.2) as a balanced
rearrangement. Comparison of the translocation break-
points of both cases by FISH, PCR of the breakpoints,
and genome-wide SNP array indicates that they are nearly
identical (Figure 1 and Figure 2; cases 10 and 11).
A comprehensive search of the literature revealed at least
ten prior reports of this translocation (Table 1 and
Table 2).
Several of these reports indicated gross
molecular positioning of the 8q and 22q breakpoints
consistent with what would be predicted on the basis of
our two cases. We subsequently received samples from two
patients carrying the supernumerar y der(22)t(8;22)
and a father-daughter pair who are t(8;22) balanced
and have performed additional analyses. As
210 The American Journal of Human Genetics 87, 209–218, August 13, 2010
Page 2
predicted, the breakpoints are identical by FISH (pa-
tient 8)
or SNP array (patient 9; Figure 1).
PCR plus
sequencing of the der(8) and der(22) junction fragments
indicates that all of the breakpoints are localized in
the PATRRs (Figures 2A and 2B; patients 8, 9, 16, and 17).
Interestingly, although the nucleotide sequence of the
individual junction fragments is nearly identical, they are
each unique. This demonstrates that the t(8;22) has
recurred independently at least five times. The junction-
fragment sequences did not identify any changes between
individuals within the same family (cases 10 and 12,
11 and 13, 16 and 17), indicating that the sequences
around the 8q and 22q breakpoints are stable in the deriv-
ative chromosomes. Thus, similar to the t(11;22), the
t(8;22) recurs and segregates 3:1 to produce unbalanced
Phenotypic Evaluation
Patients carrying the supernumerary der(22)t(8;22) have
a variable phenotype (Table 1), whereas balanced carriers
appear to be generally healthy (Table 2 ). Birth weight and
subsequent growth have been normal in all patients,
with the exception of patient 8. Dysmorphia has been
mild, the majority of patients having ear and extremity
abnormalities. All patients presented with mild delay of
developmental milestones. Interestingly, patient 9, the
oldest patient in this study, was reported to have epilepsy
and was diagnosed with large-cell non-Hodgkin lym-
Thus, although the supernumerary der(22)t
(8;22) phenotype is variable between individuals, it tends
to include ear and extremity abnormalities in addition to
mild mental retardation.
t(8;22) Recurs during Spermatogenesis
in Healthy Males
To confirm the recurrence of the t(8;22), we used PCR to
detect de novo occurrences of the t(8;22) in sperm from
healthy males. PCR was performed with the use of multiple
DNA aliquots from 33 sperm samples (eight East Asian and
25 White) and primers specific for the der(8) and/or the
der(22) junction fragments. As expected, junction frag-
ments were absent when the genomic DNA of a healthy
individual or an 11;22 balanced-translocation carrier was
amplified. Conversely, junction fragments were present
in the sperm DNA from most, but not all, healthy males
(Figure 3A). The translocation frequency was calculated
via the methods described in Kurahashi et al.
The de
novo t(8;22) frequency ranges from < 6.38 3 10
1.00 3 10
in the 33 individuals studied (Table 3). This
translocation frequency is similar to the t(11;22) frequency
derived from the short version of the chromosome 11
Unlike the t(8;22) and the t(11;22), junction
fragments from the t(1;22)
were not detected in sperm,
indicating that not all PATRR22-mediated translocations
recur during spermatogenesis.
PATRR8 Sequence Analysis
We used sequence from the der(22) and der(8) junction-
fragment PCRs from the t(8;22) balanced carriers to reas-
semble the 8q24.1 breakpoint sequence that was present
at the PATRR8 before the translocation event. Analysis
of the secondary structures of the sequence showed that
each PATRR8 contained a long, undisrupted stem-loop
structure ranging in length from 129 to 145 bp and consist-
ing of approximately 97% AT content (Figure S1) (M-Fold
sequence analysis package).
Despite the AT-rich nature
of both the PATRR8 and the PATRR22, the longest stretch
of homology between the two sequences is 13 nucleotides.
The 8q breakpoint is localized at the center of the PATRR,
supporting the hypothesis that the center of the palin-
drome is susceptible to breakage as a prerequisite to trans-
location. However, because this sequence is based only on
reconstructed junction fragments and not the sequence of
the pretranslocation PATRR8, it is possible that the actual
t(8;22) breakpoint may not be at the center of the palin-
drome because of nucleotides that have been lost during
the translocation event. The amount of sequence loss
cannot be determined because the inverted repeats seen
in these junction-fragment sequences are not present in
‘normal’ sequence included in the latest genome build
or in the Watson, Venter, and YH genomes.
the PATRR11 and PATRR22 regions are absent from the
human genome reference databases, likely because of the
difficulties in cloning and sequencing these repetitive
Figure 1. Copy-Number Output for
Chromosomes 8 and 22
Three unrelated DNA samples with a super-
numerary der(22)t(8;22) are depicted after
analysis using the Partek software copy-
number analysis suite on data derived
from running Affymetrix Genome-Wide
Human SNP Arrays 6.0. Output is shown
from short-arm telomere (left) to long-
arm telomere (right). The y axis indicates
copy number from zero to four copies.
The three DNA samples demonstrate a
duplication of distal 8q and proximal 22q,
indicating three copies of the identical
chromosomal region. *Case 10 has an
inversion on 22q.
The American Journal of Human Genetics 87, 209–218, August 13, 2010 211
Page 3
The 8q24 PATRR is flanked by two highly
homologous Alu repeats that are in an inverted orientation
with respect to one another. These Alu elements may
also contribute to the formation of hairpin or cruciform
To account for the differences in t(8;22) frequency
between individuals, we genotyped the PATRR region on
chromosome 8 in genomic and sperm DNA. Analysis of
this region suggests that there are at least four different
alleles present in the population that can be distinguished
by size through gel electrophoresis (Figure 3B). These can
be annotated according to their length: long, medium,
short, and super-short. The size of the PATRR8 appears to
correlate with the frequency of the t(8;22) in sperm. Inter-
estingly, as of yet, the long and super-short PATRR8 alleles
have not been obser ved to produce de novo translocations
in the sperm samples.
We attempted to sequence the PATRR8 region in healthy
individuals in order to further characterize this region.
We were able to sequence the PATRR8 in two East Asian
samples. Analysis of the secondary structure indicates
that each contains an undisrupted 150 bp stem-loop struc-
ture. Despite some success in sequencing this region, it has
proven to be difficult because of the extreme AT-rich
nature of the PATRR. In order to reduce the complexity
of this region by sequencing only one PATRR8 allele, we
conducted analysis of this region in t(8;22) balanced
carriers, because they have only one intact PATRR8 allele.
We amplified the PATRR8 by PCR in three t(8;22) balanced
carriers (cases 13, 16, and 17), plus a hybrid cell line carry-
ing only one copy of human chromosome 8 (GM10156B).
The resulting ~850 bp products were separated by agarose
gel electrophoresis, excised, and TA cloned in recombina-
tion-deficient Escherichia coli. A minimum of 96 clones
Figure 2. t(8;22) Junction-Fragment Sequencing
Sequence of t(8;22) der(8) (A) and der(22) (B) junction fragments from t(8;22) balanced carriers and patients carrying the supernumerary
der(22)t(8;22). The sequence is color coded by nucleotide. Stars identify nucleotides that are identical in all sequenced patients. Sequence
derived from chromosome 8 is underlined. Superscript a or b indicates a parent-child pair.
212 The American Journal of Human Genetics 87, 209–218, August 13, 2010
Page 4
were selected from each sample and sequenced. There was
significant variability in the resulting sequences, with
approximately 70% of clones being unique (Table S2).
Most of the clones contained sequence from the ends
of the PATRR8 region but lacked the nucleotides at the
center. Some appeared to contain two PATRR8s of different
lengths, suggesting that perhaps during replication in
E.coli the center of the PATRR8 is lost. None of the clones
contained an uninterrupted stem-loop structure (M-Fold
sequence analysis package). Taken together, these data
imply that this region is highly unstable even in cells
that are recombination deficient.
The Predicted t(8;11) Can Be Detected in Sperm
from Healthy Males
Because the recurrent t(8;22) and t(11;22) translocations
occur at PATRRs involving identical regions on 8q, 11q,
and 22q, we postulated that a t(8;11)(q24.1,q23) may
occur. However, there have been no prior reports of
precisely this translocation in the literature. Using an assay
similar to that used in the t(8;22) and t(11;22) PCRs, we
used previously described primers to amplify the putative
der(11)t(8;11) junction fragments in sperm samples from
healthy males.
The der(11)t(8;11) junction fragment
was detected in three samples (Figure 4), thus demon-
strating that the t(8;11) occurs during spermatogenesis in
healthy males. Sequence of the PCR products confirms
their authenticity. The de novo frequency for the t(8;11)
appears to be lower than that of the t(11;22) and t(8;22),
with a frequency of < 2.6 3 10
, based on a limited
number of samples. Nonetheless, the identification of
a palindrome-mediated rearrangement that does not
involve the PATRR22 further implicates PATRR instability
as a mechanism for mediating translocations in humans.
Table 2. Phenotypes of t(8;22) Balanced Carriers
Case Sex Age (Yrs) Other Phenotype Reference
12 M 33 father of case 10 none described Gotter et al.
13 F 36 mother of case 11 none described This study
14 M 54 - thrombocytopenia Gupta et al.
15 F 26 - myasthenia gravis, leukocytosis, thrombocytosis Keung et al.
16 F 10 - dysgerminoma Gimelli et al.
17 M - father of case 16 none described Gimelli et al.
Table 1. Phenotypes of Patients with Supernumerary der(22)t(8;22)
Inheritance Sex
Weight Growth Ears Extremities Genitalia Development/ IQ Reference
maternal M 18 normal normal prominent clinodactyly normal 50 Sanchez et al.
maternal F 29 normal normal prominent,
low set
clinodactyly normal 59 Sanchez et al.
maternal M 12 - normal - clinodactyly ectopic testes 50 Rethore et al.
maternal M 10 - normal - clinodactyly - 60 Rethore et al.
5 paternal M 16 - normal - clinodactyly ectopic testes 70 Rethore et al.
6 maternal M - - - - - - - Rethore et al.
7 maternal M 5 - - preauricular
pit, low set
- cryptorchidism no speech at
5 yrs of age
Rethore et al.
8 paternal M 5.5 normal weight,
< 3%
pit, atretic ear
clinodactyly normal moderate speech
and language
Mark et al.
9 - M 43 - - large - cr yptorchidism 50–60 Helbig et al.
10 paternal F 10 - - preauricular
- - educational
assistance via
math resource
Gotter et al.
11 maternal M 3.5 normal normal large clinodactyly - 63
This study
‘-’ indicates unknown data.
No formal testing.
Mullen Scales of Early Learning.
The American Journal of Human Genetics 87, 209–218, August 13, 2010 213
Page 5
We have identified another recurrent PATRR-mediated
constitutional translocation, the t(8;22). This transloca-
tion is capable of segregating 3:1 in meiosis to produce
abnormal offspring and occurs during gametogenesis in
healthy males. In general, individuals who are balanced
carriers of this translocation appear to be healthy. Two of
the six balanced carriers in this study were identified
only after they had a child who carries the supernumerar y
der(22)t(8;22). Two carriers have been described with
autoimmune disorders, including idiopathic thrombocy-
topenic purpura,
myasthenia gravis, leukocytosis, and
Another balanced carrier, a young girl,
was reported with a dysgerminoma.
The report of cancer
in a balanced carrier is interesting, given that the PATRR8 is
present in the first intron of RNF139 (MIM *603046),
a ubiquitin ligase that is a potential tumor-suppressor
The RNF139 protein product has been linked
to lipid homeostasis and protein-translation initiation.
This gene was first described in a family with renal cell
carcinoma carrying a t(3;8) with a breakpoint in PATRR8
(B.S.E., unpublished data). Thus, although the conse-
quences of haploinsufficiency of RNF139 have not been
reported, the observation of cancer in this limited
group of t(8;22) balanced carriers is worthy of further
The phenotype in patients carrying the supernumerary
der(22)t(8;22) is variable. Birth weight and subsequent
growth were normal in all patients except case 8. Patients
have not had any life-threatening structural abnormalities.
Extremity anomalies were noted in the majority, in addi-
tion to mild dysmorphia that includes ear abnormalities.
All patients presented with mild delay of developmental
milestones and/or mild mental retardation. This pheno-
type is in stark contrast to the severe phenotype seen in
patients with Emanuel syndrome.
Thus, the incidence
of t(8;22) is likely underascertained because of the nonspe-
cific phenotype in the affected offspring. Interestingly,
nine of the 11 patients carrying the supernumerary der
(22) t(8;22) are male. Males may be overascertained
because of the potential overlap of the supernumerary
der(22)t(8;22) syndrome phenotype with X-linked mental
retardation. As more patients with developmental delays
and mild dysmorphia are assessed with aCGH and SNP
arrays, perhaps additional individuals with supernumerary
der(22)t(8;22) will be identified, allowing for further delin-
eation of the phenotype.
Similar to the t(11;22), nondisjunction of the t(8;22)
occurs during both male and female meiosis. The site-
specific balanced translocation in the nine families we
have described is paternally inherited in three and mater-
nally derived in five (one case unknown). Two families
each have two affected siblings who carry the supernu-
merary der(22)t(8;22). The t(8;22) appears to be prone to
3:1 nondisjunction during meiosis, most likely because the
der(22)t(8;22) is small, with a short interstitial segment.
The only viable, unbalanced t(8;22) karyotype that has
been observed is 47,XX or 47,XY, þder(22)t(8;22). This is
most likely because the other unbalanced karyotypes are
likely to produce almost complete monosomy 8 upon 3:1
Figure 3. Identification of De Novo
t(8;22) in Sperm and PATRR8 Genotyping
(A) Results of der(8)t(8;22) and der(22)
t(8;22) PCR on sperm DNA from a healthy
male (sperm no.5). PCR primers were
used to generate t(8;22)-specific transloca-
tion products using 100 ng aliquots of
sperm DNA as template (1–16). The arrows
indicate the expected size of the junc-
tion fragments, and the stars denote posi-
tive reactions. All positive reactions were
sequenced and correspond to the expected
junction-fragment sequences.
(B) Results of PATRR8 PCR from genomic
DNA. Arrows indicate the four differently
sized products. They are denoted long
(L), medium (M), short (S), and super-short
(SS). The star indicates genomic DNA from
sperm no. 5 (sample shown in A).
Table 3. Frequency of De Novo t(8;22) in Sperm Samples from
Healthy Males
No. of
Positive PCRs
No. of
No. of
Samples Race
024< 6.38 x10
10 White
048< 6.38 x10
1 East Asian
1 24 1.29 3 10
8 White
3 48 1.96 3 10
2 East Asian
2 24 2.64 3 10
4 White
4 48 2.64 3 10
3 East Asian
4 24 5.52 3 10
2 White
9 48 6.29 3 10
1 East Asian
6 24 8.72 3 10
1 White
27 96 1.0 3 10
1 East Asian
Based on only der(22)t(8;22) PCR results.
Based on der(8) and der(22)t(8;22) PCR results.
214 The American Journal of Human Genetics 87, 209–218, August 13, 2010
Page 6
malsegregation, and monosomy 22 or trisomy 22 upon 2:2
malsegregation. The same phenomenon has been
observed with the t(11;22), with a few notable exceptions.
One family was reported as having multiple family
members with the karyotype: 45,XX or 45,XY, 11,-22þ
However, the chromosome
11 breakpoint of this translocation is located more distally
and the 22q11 breakpoint more proximally than the
typical t(11;22) (B.S.E., unpublished data). This suggests
that the phenotype that emerges from this ‘variant’
t(11;22) rearrangement segregating the der(11) is more
compatible with live birth than would be the case for the
typical t(11;22). In addition, three patients have been
described with 47,XX or 47,XY,t(11;22)(q23;q11),þder(22)
t(11;22), the result of nondisjunction in meiosis II.
The t(8;22) is recurrent and arises in sperm from healthy
males at a frequency of approximately 2 3 10
. According
to studies published by Thomas et al.,
there is a propen-
sity for structural chromosome abnormalities to occur in
male germ cells. This has been recently confirmed for the
The fact that a hypothetical t(8;11) rearrange-
ment can be identified in male germ cells adds credence
to this hypothesis. However, because none of the t(8;22)
rearrangements we have studied to date are de novo, it is
difficult to determine whether such PATRR-mediated rear-
rangements can occur in female as well as male meiosis.
It is striking that the 11;22, 8;22 and 8;11 translocations
recur in meiosis to varying degrees whereas the t(1;22) and
do not. The absence of the t(17;22) is particu-
larly interesting because this translocation has been
observed in two independent families. This may be the
result of differences in the configurations of the PATRR1
and PATRR17 that make them less susceptible to double-
strand breaks than the PATRR8 or PATRR11 during meiosis.
Alternatively, the position of chromosome 1 or 17 in rela-
tion to chromosome 22 in the interphase meiotic nucleus
may preclude frequent interactions between them, making
chromosomal rearrangement unlikely.
As data emerge
regarding the position of chromosomal domains during
meiosis, this discrepancy might be clarified. Nonetheless,
the absence of the t(1;22) and t(17;22) during meiosis indi-
cates that not all PATRR22-mediated translocations occur
with a measurable frequency during gametogenesis in
healthy males. The identification of the t(8;22) and
t(8;11) during meiosis is evidence that these rearrange-
ments recur at a frequency that can be assessed.
The t(8;22) frequency during spermatogenesis is highly
variable between individuals. The frequency of the
t(11;22) also varies, and this variation is related to the poly-
morphic sequences at the 11q and 22q breakpoints.
PATRR8 is flanked by two highly homologous Alu repeats
that are in an inverted orientation with respect to one
another. Given the high sequence similarity and inverted
orientation, these Alu elements may also induce the forma-
tion of hairpin or cruciform structures and may play a role
in further destabilization of the PATRR8 region. Genomic
variations resulting from the polymorphic presence or
absence of one or both of these Alu elements, as well as
variability in the PATRR8 itself, may affect the ability of
the 8q24 PATRR to undergo rearrangement. We have
sequenced this region in a small set of individuals, but
we have been unable to obtain the full sequence of the
PATRR8 in the majority. The complete PATRR8 sequence
from the 8q breakpoint is missing from genomic databases,
most likely because of the difficulty of sequencing this and
other AT-rich palindromic regions. It is likely that current
next-generation sequencing techniques will also be com-
promised in the analysis of such repetitive regions as
a result of short reads and shotgun approaches. Thus,
further characterization of the PATRR8 and surrounding
sequence will require novel methods, but will hopefully
explain the differences in t(8;22) frequency in sperm and
provide insights into the mechanism of palindrome-medi-
ated translocations.
Because the PATRRs on 11q and 8q are both good
substrates for double-strand break and rearrangement, we
hypothesized that t(8;11)(q24.1,q23) may occur. Indeed,
this translocation does occur at a low rate during spermato-
genesis in healthy males. Studies including additional
sperm samples are necessary to more accurately estimate
the frequency of this translocation. However, the fre-
quency appears to be very low and may again be related
to the polymorphic characteristics of the PATRR8 and
PATRR11 or to the proximity of chromosomes 8 and 11
during meiosis. There are four reports of translocations
between chromosomes 8 and 11 in the literature. Two of
the four describe translocations involving 11p.
third reported t(8;11) involves breakpoints in 8q24 and
The fourth reports a translocation with break-
points in 8q24.3 and 11q23. The breakpoints of this
translocation have not been fully characterized, but on
the basis of cytogenetic characterization, the 8q break-
point does not appear to be in the PATRR8.
Thus, a
t(8;11)(q24.1,q23) has not been reported in the literature.
There are a number of potential reasons why this
Figure 4. Identification of De Novo t(8;11) in Sperm
Results of der(11)t(8;11) PCR on sperm DNA from a healthy East
Asian male. Nested PCR primers were used to generate t(8;11)-
specific translocation products using 250 ng aliquots of sperm
DNA as template (1–16). The arrow indicates the expected size
of the der(11)t(8;11) junction fragment, and the stars denote
two der(11)t(8;11)-positive reactions. The positive reactions
were sequenced and correspond to the expected der(11)t(8;11)
The American Journal of Human Genetics 87, 209–218, August 13, 2010 215
Page 7
specific palindrome-mediated translocation has not been
described. It is likely that balanced carriers do not have
a phenotype and do not come to the attention of physi-
cians, whereas unbalanced genotypes are likely to be
incompatible with life. Furthermore, the translocation
would be difficult to detect with standard cytogenetic
techniques. Nevertheless, the identification of the t(8;11)
in sperm provides evidence that palindrome-mediated
genomic instability leading to translocation is a general
mechanism that is not dependent on the PATRR22
sequence. The previous report of a t(3;8)
whose break-
points have now been identified in PATRR8 and a PATRR
on chromosome 3 (B.S.E., unpublished data) add further
support for this phenomenon.
In conclusion, we have identified another recurrent,
palindrome-mediated translocation. The identification of
additional patients who carry the supernumerary der(22)
t(8;22) will help to further characterize the phenotype asso-
ciated with nondisjunction of the t(8;22). In addition, the
continued study of the t(8;22) and t(8;11) frequencies and
breakpoints as well as the PATRR8 sequence in the general
population is likely to provide further insights into the
mechanism of palindrome-mediated genomic instability.
Supplemental Data
Supplemental Data include two tables and one figure and can be
found with this article online at
The authors wish to thank C. Coutifaris and E. Wigo for providing
sperm samples from healthy males, E. Geiger and the Nucleic Acid
and Protein Core at the Children’s Hospital of Philadelphia for
technical assistance, and the patients and their families for their
willingness to participate in this study. This study was supported
by grants CA39926 and HD26979 and funds from the Charles
E.H. Upham chair in pediatrics (to B.S.E.).
Received: May 14, 2010
Revised: July 7, 2010
Accepted: July 11, 2010
Published online: July 29, 2010
Web Resources
The URLs for data presented herein are as follows:
M-Fold sequence analysis package,
Online Mendelian Inheritance in Man (OMIM), http://www.ncbi.
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  • Source
    • "(PATRR22), respectively [Edelmann et al., 2001; Kurahashi and Emanuel, 2001a; Tapia-Paez et al., 2001]. PA- TRR22 also mediates additional translocations with four other PA- TRRs, suggesting PATRR-mediated translocations as one of the universal pathways for chromosomal rearrangements [Kehrer-Sawatzki et al., 1997; Kurahashi et al., 2003; Nimmakayalu et al., 2003; Gotter et al., 2004; Gotter et al., 2007; Sheridan et al., 2010]. With the exception of t(17;22)(q11;q11.2), "
    [Show abstract] [Hide abstract] ABSTRACT: Palindromic sequences can form hairpin structures or cruciform extrusions, which render them susceptible to genomic rearrangements. A 197 bp long palindromic AT-rich repeat (PATRR17) is located within intron 40 of the neurofibromatosis type 1 (NF1) gene (17q11.2). Through comprehensive NF1 analysis, we identified six unrelated patients with a rearrangement involving intron 40 (five deletions and one reciprocal translocation t(14;17)(q32;q11.2)). We hypothesized that PATRR17 may be involved in these rearrangements thereby causing NF1. Breakpoint cloning revealed that PATRR17 was indeed involved in all of the rearrangements. As microhomology was present at all breakpoint junctions of the deletions identified, and PATRR17 partner breakpoints were located within 7.1 kb upstream of PATRR17, fork stalling and template switching (FoSTeS)/microhomology-mediated break-induced replication (MMBIR) was the most likely rearrangement mechanism. For the reciprocal translocation case, a 51 bp insertion at the translocation breakpoints mapped to a short sequence within PATRR17, proximal to the breakpoint, suggesting a multiple stalling and re-replication process, in contrast to previous studies indicating a purely replication-independent mechanism for PATRR-mediated translocations. In conclusion, we show evidence that PATRR17 is a hotspot for pathogenic intragenic deletions within the NF1 gene and suggest a novel replication-dependent mechanism for PATRR-mediated translocation.This article is protected by copyright. All rights reserved
    Full-text · Article · Jul 2014 · Human Mutation
  • Source
    • "The later group comprises at present 23 different breakpoints involved 2 to 14 times in one of the 73 complex sSMC. As reason for this preference several mechanisms are discussed, including palindrome mediated recurrent translocations [6] , homologous recombination between olfactory receptor gene clusters [7] or an involvement of fragile sites in the formation of constitutional breakpoints [8]. While the formation of complex sSMC due to a parental balanced translocation is comprehensible, it is unclear how such sSMC are formed de novo. "
    [Show abstract] [Hide abstract] ABSTRACT: Complex small supernumerary marker chromosomes (sSMC) constitute one of the smallestsubgroups of sSMC in general. Complex sSMC consist of chromosomal material derived from more than one chromosome; the best known representative of this group is the derivative chromosome 22 {der(22)t(11;22)} or Emanuel syndrome. In 2008 we speculated that complex sSMC could be part of an underestimated entity. Here, the overall yet reported 412 complex sSMC are summarized. They constitute 8.4% of all yet in detail characterized sSMC cases. The majority of the complex sSMC is contributed by patients suffering from Emanuel syndrome (82%). Besides there are a der(22)t(8;22) (q24.1;q11.1) and a der(13)t(13;18)(q11;p11.21) or der(21)t(18;21)(p11.21;q11.1) = der(13 or 21)t(13 or 21;18) syndrome. The latter two represent another 2.6% and 2.2% of the complex sSMC-cases, respectively. The large majority of complex sSMC has a centric minute shape and derives from an acrocentric chromosome. Nonetheless, complex sSMC can involve material from each chromosomal origin. Most complex sSMC are inherited form a balanced translocation in one parent and are non-mosaic. Interestingly, there are hot spots for the chromosomal breakpoints involved. Complex sSMC need to be considered in diagnostics, especially in non-mosaic, centric minute shaped sSMC. As yet three complex-sSMC-associated syndromes are identified. As recurrent breakpoints in the complex sSMC were characterized, it is to be expected that more syndromes are identified in this subgroup of sSMC. Overall, complex sSMC emphasize once more the importance of detailed cytogenetic analyses, especially in patients with idiopathic mental retardation.
    Full-text · Article · Oct 2013 · Molecular Cytogenetics
  • Source
    • "Interestingly, DNA sequences close to the breakpoint mapped in CFS showed the potential to form secondary structures with frequent AT-rich flexible cluster [45]. These favored sites for chromosomal breakpoints are notably observed in the Robertsonian translocation [46], in the Emanuel syndrome [47] [48] or in five other characterized translocations [49] [50] [51] [52] [53]. As a consequence , these specific loci are preferential integration site for foreign DNA [54] [55] [56] [57] or chromosomal rearrangements that lead to numerous gene deletion, such as FRA3B that contains the tumor suppressor gene FHIT [58] or chromosomal amplification as those located in FRA7I loci that is implicated in breast cancer [59]. "
    [Show abstract] [Hide abstract] ABSTRACT: In addition to the canonical right handed double helix, DNA molecule can adopt several other non B-DNA structures. Readily formed in the genome at specific DNA repetitive sequences, these secondary conformations present a distinctive challenge for progression of DNA replication forks. Impeding normal DNA synthesis, cruciforms, hairpins, H-DNA, Z-DNA and G4 DNA considerably impact the genome stability and in some instances play a causal role in disease development. Along with previously discovered dedicated DNA helicases, the specialized DNA polymerases emerge as major actors performing DNA synthesis through these distorted impediments. In their new role, they are facilitating DNA synthesis on replication stalling sites formed by non B-DNA structures and thereby helping the completion of DNA replication, a process otherwise crucial for preserving genome integrity and concluding normal cell division. This review summarizes the evidence gathered describing the function of specialized DNA polymerases in replicating DNA through non B-DNA structures.
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