2015, Volume 31, Number 1, Page(s) 036-044
Rare Structural Chromosomal Abnormalities in Prenatal Diagnosis; Clinical and Cytogenetic Findings on 10125 Prenatal Cases
Sezin YAKUT1, Zafer ÇETİN1, Mehmet ŞİMŞEK2, İbrahim İnanç MENDİCİOĞLU2, Havva Serap TORU3, Sibel BERKER KARAÜZÜM1, Güven LÜLECİ1
1Department of Medical Biology and Genetics, Akdeniz University, School of Medicine, ANTALYA, TURKEY
2Department of Obstetrics and Gynecology, Akdeniz University, School of Medicine, ANTALYA, TURKEY
3Department of Pathology, Akdeniz University, School of Medicine, ANTALYA, TURKEY
Keywords: Prenatal diagnosis, Cytogenetics, Chromosomal aberrations, Autopsy
The aim of this study was presentation of the
ultrasonographic findings and perinatal autopsy of cases with rare
Material and Method: A total of 10125 prenatal cases over 17 years
including 8731 amniocentesis, 973 chorionic villus sampling, and 421
fetal blood sampling cases were evaluated for prenatal cytogenetic
diagnosis. Conventional cytogenetic studies, fluorescence in situ
hybridization studies, and Array-CGH analysis techniques were used
for genetic analysis.
Results: A structural chromosomal abnormality was observed in
95 cases. The most frequently observed structural abnormalities
were balanced translocations with a frequency of 53.7% (51 cases)
followed by unbalanced translocations (16.8%), inversions (11.6%),
supernumerary marker chromosomes (8.4%), duplications (4.2%),
deletions and ring chromosomes (2.1%) and complex translocation
(1.1%). Rare structural chromosomal abnormalities including de
novo balanced translocations, unbalanced translocations, inversions,
duplications, deletions, ring chromosomes, and supernumerary
marker chromosomes were detected in 24 cases.
Conclusion: The rate of rare chromosomal abnormalities varies from
2.4% (South East Ireland) to 12.9% (Northern England) in Europe
with a total rate of 7.4/10 000 births. In our study, the overall rate
of chromosomal abnormality in prenatal cytogenetic diagnosis was
3.7%, similar to South East Ireland. Ultrasonographic and perinatal
autopsy findings of the cases with rare structural chromosomal
abnormalities are important for proper genetic counseling for further
Prenatal diagnosis with conventional cytogenetic analysis
has been recognized for more than 30 years as a safe and
reliable method for couples at increased risk of having a
child with a clinically significant chromosomal abnormality1
. The application of prenatal diagnosis has been
increased due to advances in screening maternal serum
markers, ultrasonography, and increasing maternal age.
Early detection of chromosomal abnormalities during
pregnancy is important for proper genetic counseling and
for management of informed decisions about continuing or
terminating the pregnancy2
. Some of these numerical and
structural chromosomal abnormalities are uncommon in
prenatal diagnosis and correlations between these cytogenetic
findings and ultrasonographic findings, clinical outcomes of
the pregnancies and follow-up of the fetuses with these rare
chromosomal abnormalities are very important to provide
genetic counseling for further similar cases3
In this study, we report a single center experience of
rare structural chromosomal abnormalities detected
during prenatal diagnosis over 17 years and also the
ultrasonographic and perinatal autopsy findings associated
with rare chromosomal abnormalities that are very
important for physicians and geneticists in proper genetic
In this study, 8731 amniocentesis (AC),
973 chorionic villus (CVS) and 421 fetal blood samples
representing 17 years of experience at Akdeniz University
Hospital in Turkey were analyzed cytogenetically. The
indications for prenatal karyotyping included advanced
maternal age (>35), increased risk in double, triple or
quadruple test screening, abnormal ultrasonographic
finding, previous chromosomal abnormalities, family
history of a previous child with chromosomal abnormality
Conventional Cytogenetic Studies: The amniocytes and
chorionic villus samples were cultivated in two or three
different flasks containing 2 ml AmnioGrow (Cytogen
GmbH, Bienenweg, Germany) and Chang Medium-D
(Irvine scientific, Santa Ana, CA, USA) and fetal blood
samples were cultivated using the short-term cell culture (72
hour) technique. Parents' karyotypes were also evaluated
by using a standard method for G-banding (GTG) in order
to determine whether the abnormality found in the fetus
was de novo or inherited. If the fetus was found to have
a chromosomal abnormality or a polymorphism, CBG
and NOR banding analysis were applied for identification and characterization of abnormal chromosomes and
polymorphisms. Karyotypes were described according
to the International System for Human Cytogenetic
Nomenclature4. A minimum of 20 metaphases from
two cultures were analyzed. Mosaicism was considered
when the same abnormality was seen in more than two
metaphases in two different cultures5.
Fluorescence In Situ Hybridization (FISH) Studies:
FISH tests were performed using Prader Willi/Angelman
syndrome and Down Syndrome Critical region dual color
locus specific probes (Aquarius TM probes-Cytocell®; Oxon;
UK) according to the manufacturer's instructions. At least
15 metaphase plates were analyzed. FISH analysis using
the Chromoprobe Multiprobe-I System (Cytocell, Rainbow
Scientific, Inc., Windsor, CT) and SpectraVysion Multicolor
FISH system (Vysis Inc, Downers Grove, Illinois, USA) were
performed according to the manufacturer's instructions to
detect the origin of the marker chromosomes. At least 5
metaphase plates were analysed from each square on the
Multiprobe–I system and SpectraVysion Multicolor FISH
system. Also, one hundred interphase nuclei were analysed
from uncultured amniocytes by using centromeric probes in
order to discriminate real mosaicisms from culture artifacts.
Images were recorded using a Zeiss Axioplan epifluorescence
microscope equipped with a CCD camera (Photometrics
Sensys) and analysed using MacProbe v 4.3 software.
Array-CGH Analysis: Array-CGH analysis were performed
using genomic DNA samples obtained from amniocytes
of the cases, according to the manufacturer's protocol
for Cytogenetics Whole Genome 2,7 M oligonucleotide
catalog array (Affymetrix Inc., Santa Clara, CA, USA). The
microarray image data were scanned by GeneChip® 7G
High Resolution Scanner using the Command Console
software (Affymetrix Inc., Santa Clara, CA, USA). Data
were analyzed using the Chromosome Analysis Suit Version
1.0 (Affymetrix Inc., Santa Clara, CA, USA).
During 17 years, 10125 prenatal cases including 8731
AC, 973 CVS, and 421 fetal blood samples were evaluated
for prenatal cytogenetic diagnosis. The number of CVS
samples significantly increased in recent years. The rate
of culture failure, due to cell culture growing problems,
microbial contaminations and unsuitable/insufficient
material was 0.67%. Culture failure was observed mostly in
CVS material but significantly decreased through the years.
The overall culture success rate was 99.33%. The overall
rate of chromosomal abnormality in prenatal cytogenetic
diagnosis was 3.7%.
All chromosome abnormalities were classified into the following
categories: numerical abnormalities (autosome and
sex chromosomes), balanced translocations, unbalanced
translocations, inversions, supernumerary marker chromosomes,
deletions, duplications, complex rearrangements
and ring chromosomes. Heterochromatin variations of the
chromosomes 1, 9, 16 and Y and nucleolus organizer regions
of chromosomes of D and G group were not reported.
In our cohort, 8 cases with de novo balanced reciprocal
translocations were observed. Case 1 with t(4;15)(q23;q26,1)
de novo balanced reciprocal translocation, cystic hygroma
and hydrops fetalis was detected with USG abnormalities.
Case 2 with de novo t(2;7)(p21;p22) balanced reciprocal
translocation had unilateral radial club hand, radius aplasia,
ulnar hipoplasia and thumb hipoplasia as ultrasonographic
findings. These balanced reciprocal translocations in
conjunction with the ultrasonographic findings have rarely
been reported. After genetic counseling, the pregnancies
were terminated according to the parents' requests in both
cases. Postmortem evaluations revealed facial abnormalities,
cystic hygroma, hydrops fetalis and bilateral ventricular
dilatation in case 1. Facial abnormalities, forearm and
hand malformations were observed during postmortem
evaluations of case 2 (Figure 1).
Click Here to Zoom
|Figure 1: Fetus with cleft lip and palate, low-set ears, depressed
nasal bridge, radial club hand, radius aplasia, ulnar hypoplasia,
thumb hypoplasia (Case 2).
In case 3, co-existence of 6q25.3-qter monosomy and
18q21.3 trisomy due to de novo unbalanced translocation
between chromosomes 6 and 18 was detected in association
with bilateral ventriculomegaly and choroid plexus cysts as
In case 4, monosomy of the 18p11-pter region due to de
novo unbalanced translocation between 13p11.1 and 18p11
chromosome bands was detected in association with bilateral
ventricular dilatation. In case 5, monosomy 18p due to de
novo unbalanced translocation between chromosomes
18 and 22 along with increased nuchal transluency was
observed prenatally. Case 6 had unbalanced translocation
resulted with 6q25 monosomy and associated with bilateral
In the case 7, de novo 46,XY,der(15)t(15;18)(q13.1;p11.2)
unbalanced translocation resulted in partial monosomy
of the chromosome 15q13.1-qter and partial trisomy of
chromosome 18p11.2-pter and oligohydramnios was
detected as the ultrasonographic finding. Micrognathia,
low-set ears, down-slanting palpebral fissures, flexion
deformity on right hand, rocker-bottom foot were detected
on postmortem evaulation.
We found 11 cases with pericentric inversions of chromosomes
3, 12, 17, Y and paracentric inversions of the
chromosomes 6, 10 and 14. Five of eleven cases had rare
forms of inversions such as inv(12)(p11.22q13.13)pat,
inv(12)(p11.22q13.1)mat, inv(3)(p21.3q12)mat, inv(10)
(q11.2q23.2)pat and inv(6)(q25.1q25.3)pat inversions. Ultrasonographic
screenings did not reveal any fetal abnormalities
in these five cases. After the genetic counseling, all
of the five families decided to carry the pregnancy to term.
The follow-up evaluations of the babies were normal.
We have observed rare euchromatin variants in three
cases leading to duplications of 9p11.21-13.1, 9q13-21.12,
15q11-13 chromosome regions. 15q11q13 duplications
were maternally transmitted to the fetus and FISH results
using Prader Willi/Angelman syndrome dual color
locus specific probes showed that duplicated region did
not contain the PWS/AS critical region. We found two
prenatal cases with maternally inherited duplications of
chromosome 9p11.2-p13.1 and 9q13-q21.12. Duplication
of the 9p11.2-p13.1 region in case 21 was confirmed by
array CGH analysis.
We observed de novo interstitial deletion of the 5q13-q22
and 1q22-q25 chromosome regions in case 18 and 19 who
were referred for amniocentesis due to increased nuchal
transluency and bilateral pyelectasis, respectively. In both
cases the pregnancies were terminated due to the abnormal
cytogenetic findings. Postmortem evaluations of case 18
revealed facial abnormalities, broad neck, posterolateral
diaphragmatic hernia, bilateral club foot, unilateral kidney
agenesis, and thymic dysplasia. Facial abnormalities,
flexion deformity on hands and feet and cardiomegaly were
observed during postmortem evaluations in case 19.
We detected eight supernumerary marker chromosomes
in our cohort with a frequency of 0.079%. In five of
these cases, the chromosomal origins of the marker
chromosomes were clarified by FISH using Chromoprobe
Multiprobe-I and SpectraVysion Multicolor FISH probes.
In two of the cases, supernumarary marker chromosomes
originated from chromosome 15 and the other one was
from chromosome 13 or 21. In the remaining three cases,
the families did not accept further molecular cytogenetic
studies for the detection of the origin of supernumerary
In case 23 with de novo mosaic ring chromosome 13,
breakpoints were located at p11 and q32 bands. Prenatal
cytogenetic analyses were performed because of multiple
ultrasonographic findings. The pregnancy was terminated.
However, the details of the ultrasonographic findings and
postmortem evaluations were not available.
We detected de novo ring chromosome 21 in one case.
Possible duplication or deletion of the Down syndrome on
the critical region of the ring chromosome 21 was excluded
by FISH analysis using Down Syndrome Critical region
dual color locus specific probes. Genetic counseling was
given to parents considering the existence of monosomy 21
mosaicism. The family decided to terminate the pregnancy.
Structural abnormalities were observed in 95 cases. The
most frequent structural abnormalities were balanced
translocations with a frequency of 53.7% (51 cases)
followed by unbalanced translocations (16.8%), inversions
(11.6%), supernumerary marker chromosomes (8.4%),
duplications (4.2%), deletions and ring chromosomes (2.1%) and complex translocation (1.1%) (Table I).
Familial transmission status of the structural chromosomal
abnormalities was as follows; de novo in 47 cases (49.5%),
maternal in 30 cases (31.6%), and paternal in 18 cases
(18.9%). Mosaicism was not detected in 83 of 95 cases with
a structural chromosomal abnormality (87.4%), whereas in
12 cases, structural chromosome abnormalities were in a
mosaic state (12.6%). Rare chromosomal abnormalities and
the clinical details of these fetuses are presented in Table II.
We presented here rare cases with balanced translocations
associated with USG findings, unbalanced translocations,
inversions, duplications / rare euchromatin variants,
deletions, supernumerary marker chromosomes and ring
In newborn studies, the rate of chromosomal abnormalities
is 17-31/10.000 births6-7. The chromosomal abnormality
rate in misscarried or stillbirth fetuses is 43.6/10.000 births8. As expected the rate of chromosomal abnormalities
varies between prenatal and postnatal sources. The rate of
rare chromosomal abnormalities varies from 2.4% (South
East Ireland) to 12.9% (Northern England) in Europe with
the total rate of 7.4/10 000 births8. In our study the overall
rate of chromosomal abnormality in prenatal cytogenetic
diagnosis was 3.7%, similar to South East Ireland in Europe.
Balanced translocations; It has been accepted that familial
balanced translocations detected by prenatal diagnosis
are not associated with phenotypical abnormalities9.
However, in 6% of the prenatally detected de novo balanced
reciprocal translocations have been associated with a risk of important congenital abnormalities10. Congenital
malformations in apparently balanced translocations
might resulted microdeletions or gene disruption at the
breakpoints or formation of a new rearrangement that
leads to a altered gene function10. In our cohort, cases
with de novo balanced reciprocal translocations had
several anomalies. Detailed USG and follow-up evaluations
should be performed prenatally in cases with an apparently
Unbalanced Translocations; There is no report on a prenatal
case with choroid plexus cysts and 6q25.3-qter monosomy
or 18q21.3 trisomy. Previous reports on postnatal cases
indicate that enlargement in lateral ventricles can be
observed in cases with 6q25 monosomy11,12. Our case
is the first prenatally evaluated case showing an association
between 6q25 monosomy and bilateral ventriculomegaly.
Chromosome 6q25-qter region must therefore be kept in
cases with bilateral ventriculomegaly as an ultrasonographic
Several reports on prenatally detected pure and complete
monosomy 18p due to unbalanced translocations between
chromosome 18 and acrocentric chromosomes
have been previously published. In these cases, prenatal
ultrasonographic findings including increased nuchal
translucency thickness and holoprosencephaly were evident13-17. In monosomy 18p, supraorbital flatness, depressed
nasal bridge, flared nostrils and low-set ears were observed
during postmortem evaluations18. However, case 4 is the
first prenatal case with pure and complete monosomy 18p
presenting with bilateral ventricular dilatation as the only
ultrasonographic finding. Postmortem evaluations showed;
micrognathia, depressed nasal bridge and hypoplasia of
lung and kidney.
Inversions; Chromosome 2 displays the highest frequency
for pericentric inversion, while chromosome 3 and 7 are
most often involved in paracentric inversions19. To
the best of our knowledge, inv(12)(p11.22q13.13)pat,
inv(12)(p11.22q13.1)mat, inv(3)(p21.3q12)mat, inv10
(q11.2q23.2)pat and inv(6)(q25.1q25.3)pat inversions have
not been reported previously in prenatal diagnosis.
Duplications/ Rare Euchromatin Variants; 15q11q13
duplications can be observed in clinically normal
individuals and also in affected patients depending on the
presence of the PWS/AS critical region20. In our case,
duplication was maternally transmitted to the fetus and
the duplicated region did not contain the PWS/AS critical
region. Cases with dup(15)(q11q13) are rarely reported
in prenatal cases and the previous reported five fetuses were born and were phenotypically normal21. To our
knowledge, our case is the sixth fetus with familial dup15
(q11q13) prenatally detected. Genetic counseling was given
to parents according to the literature and the family decided
to continue the pregnancy that resulted in normal pregnancy
outcome. Duplications of chromosome 9p11.2-p13.1 and
9q13-q21.12 have been previously reported as uncommon
euchromatin variants that are associated with a normal
phenotype22. In both of our cases the pregnancies were
continued to term and the babies were born without any
Deletions; In the literature, 4.7% of 11 chromosomal
abnormalities were deletions8. In contrast to the
literature, only 2% of all were deletions in our study.
Interstitial deletions in chromosomes 1 and 5 are rarely
reported23,24. To our knowledge, interstitial deletions of
5q13-q22 and 1q22-q25 chromosome regions in prenatal
diagnosis were observed for first time in our study.
Supernumerary Marker Chromosomes; Marker chromosomes
are supernumerary structurally abnormal chromosomes
with unknown origin, and might be found with a frequency
of 0.075% and 0.044% in prenatal and postnatal diagnosis,
respectively25. Most of the supernumerary marker
chromosomes originate from acrocentric chromosomes
according to the literature. However, marker chromosomes
originating from certain human chromosomes such
as supernumerary marker chromosomes derived from
chromosome 16 and 17 are rare. As we previously reported,
our case with marker chromosome that originated from
chromosome 16 is the third phenotypically normal case
and had been followed-up until 7 months of age26. Also,
as we previously discussed, the case with supernumerary
marker chromosome that originated from chromosome 17
is the second prenatally detected case continued to term
and the follow-up revealed no clinical findings27,28.
Ring Chromosomes; De novo mosaic ring chromosome 13
breakpoints were located at the p11 and q32 bands. To our
knowledge only one prenatal case has been reported. Chen
et al., (2001) reported intrauterine growth retardation,
a widely open mouth and absence of the cranial vault
as ultrasonographic findings. Post mortem evaluations
revealed anencephaly, hypertelorism, large low-set
ears, micrognathia, retroflexed hands and feet without
hypoplastic aplastic thumbs and toes29. We had one case
with prenatally detected USG abnormalities.
Ring chromosome 21 is a rare chromosomal abnormality
often associated with mental retardation and dysmorphic
features30-33. Less commonly, the ring chromosome can be familial and associated with a normal phenotype but
at increased risk of having children with Down syndrome34,35. We had one case with de novo ring chromosome
In conclusion, detection of rare chromosomal abnormalities
associated with ultrasonographic and perinatal autopsy
findings are very important for physicians and geneticists
for proper genetic counseling.
Funding Source: This study was supported by the Akdeniz
University Scientific Research Project Management Unit.
1) Dallaire L. Integration of prenatal diagnosis of genetic diseases
into medical practice. Can Med Assoc J. 1976;115:713-4.
2) Stembalska A, Slezak R, Pesz K, Gil J, Sasiadek M. Prenatal
diagnosis-principles of diagnostic procedures and genetic
counseling. Folia Histochem Cytobiol. 2007;45 Suppl 1:S11-6.
3) Baena N, De Vigan C, Cariati E, Clementi M, Stoll C, Caballin
MR, Guitart M; EUROSCAN Working Group. Prenatal detection
of rare chromosomal autosomal abnormalities in Europe. Am J
Med Genet A. 2003;118A:319-27.
4) An international system for human cytogenetic nomenclature.
Shaffer LG, Slovak ML, Campbell LJ, editors. Basel: Karger Press;
5) Chromosome abnormalities and genetic counseling. 4th ed.
Gardner RJM, Sutherland GR, Shaffer LG, editors. New York:
Oxford University Press; 2011.
6) Hamerton JL, Canning N, Ray M, Smith S. A cytogenetic
survey of 14,069 newborn infants. I. Incidence of chromosome
abnormalities. Clin Genet. 1975;8:223-43.
7) Dolk H, Loane M, Garne E. The prevalence of congenital
anomalies in Europe. Adv Exp Med Biol. 2010;686:349-64.
8) Wellesley D, Dolk H, Boyd PA, Greenlees R, Haeusler M, Nelen
V, Garne E, Khoshnood B, Doray B, Rissmann A, Mullaney C,
Calzolari E, Bakker M, Salvador J, Addor MC, Draper E, Rankin
J, Tucker D. Rare chromosome abnormalities, prevalence and
prenatal diagnosis rates from population-based congenital
anomaly registers in Europe. Eur J Hum Genet. 2012;20:521-6.
9) Chen CP, Wu PC, Lin CJ, Su YN, Chern SR, Tsai FJ, Lee CC,
Town DD, Chen WL, Chen LF, Lee MS, Pan CW, Wang W.
Balanced reciprocal translocations detected at amniocentesis.
Taiwan J Obstet Gynecol. 2010;49:455-67.
10) Warburton D. De novo balanced chromosome rearrangements
and extra marker chromosomes identified at prenatal diagnosis:
Clinical significance and distribution of breakpoints. Am J Hum
11) Koh S, Boles RG. Cerebral aqueductal stenosis as a presentation
of deletion 6q25-qter. Clin Genet. 1998;53:317-8.
12) Cavani S, Perfumo C, Faravelli F, Malacarne M, Sogliani M, Piombo
G, Zerega G, Zucca M, Dagna Bricarelli F, Pierluigi M. Cryptic
1p36.3/6q25.2 translocation in three generations ascertained
through a foetus with IUGR and cerebral malformations. Prenat
13) Sepulveda W. Monosomy 18p presenting with holoprosencephaly
and increased nuchal translucency in the first trimester: Report of
2 cases. J Ultrasound Med. 2009;28:1077-80.
14) Agarwal S, Oppenheimer CA, Howarth ES, Khare MM. A case of
monosomy 18p diagnosed on the basis of an isolated finding of
increased nuchal fold thickness. J Obstet Gynaecol. 2009;29:548-9.
15) E dwards S, Waters JJ. Prenatal diagnosis of monosomy 18p
involving a jumping translocation. Prenat Diagn. 2008;28:764-6.
16) Kim YM, Cho EH, Kim JM, Lee MH, Park SY, Ryu HM. Del(18p)
syndrome with increased nuchal translucency in prenatal
diagnosis. Prenat Diagn. 2004;24:161-4.
17) McGhee EM, Qu Y, Wohlferd MM, Goldberg JD, Norton
ME, Cotter PD. Prenatal diagnosis and characterization of an
unbalanced whole arm translocation resulting in monosomy for
18p. Clin Genet. 2001;59:274-8.
18) Y akut S, Simsek M, Pestereli HE, Baumer A, Luleci G, Schinzel A.
Del (18p) syndrome with increased nuchal translucency revealed
in prenatal diagnosis. Genet Couns. 2011;22:317-9.
19) Muss B, Schwanitz G. Characterization of inversions as a type of
structural chromosome aberration. Int J Hum Genet. 2007;7:141-61.
20) L udowese CJ, Thompson KJ, Sekhon GS, Pauli RM. Absence of
predictable phenotypic expression in proximal 15q duplications.
Clin Genet. 1991;40:194-201.
21) Browne CE, Dennis NR, Maher E, Long FL, Nicholson JC,
Sillibourne J, Barber JC. Inherited interstitial duplications of
proximal 15q: genotype-phenotype correlations. Am J Hum
22) Di Giacomo MC, Cesarano C, Bukvic N, Manisali E, Guanti
G, Susca F. Duplication of 9 p11.2-p13.1: A benign cytogenetic
variant. Prenat Diagn. 2004;24:619-22.
23) Malan V, Martinovic J, Sanlaville D, Caillat S, Waill MC, Ganne
ML, Tantau J, Attie-Bitach T, Vekemans M, Morichon-Delvallez
N. Molecular characterisation of a prenatally diagnosed
5q15q21.3 deletion and review of the literature. Prenat Diagn.
24) Descartes M, Hain JZ, Conklin M, Franklin J, Mikhail FM,
Lachman RS, Nolet S, Messiaen LM. Molecular characterization
of a patient with an interstitial 1q deletion [del(1)(q24.1q25.3)]
and distinctive skeletal abnormalities. Am J Med Genet A.
25) L iehr T, Mrasek K, Hinreiner S, Reich D, Ewers E, Bartels I,
Seidel J, Emmanuil N, Petesen M, Polityko A, Dufke A, Iourov
I, Trifonov V, Vermeesch J, Weise A. Small supernumerary
marker chromosomes (sSMC) in patients with a 45,X/46,X,+mar
karyotype - 17 new cases and a review of the literature. Sex Dev.
26) Y akut S, Cetin Z, Simsek M, Karauzum SB, Tukun A, Luleci
G. Prenatal diagnosis of a de novo supernumerary marker
chromosome originating from chromosome 16. Genet Couns.
27) L iehr T. Small supernumerary marker chromosomes (sSMCs):
A spotlight on some nomenclature problems. J Histochem
Cytochem. 2009;57: 991-3.
28) Y akut S, Cetin Z, Berker-Karauzum S, Mihci E, Mendilcioglu
I, Luleci G. De novo supernumerary marker chromosome
originating from chromosome 17 resulting in a normal pregnancy
outcome. Genet Couns. 2011;22:63-8.
29) Chen CP, Chern SR, Lee CC, Chen WL, Wang W. Prenatal
diagnosis of mosaic ring chromosome 13 with anencephaly.
Prenat Diagn. 2001;21:102-5.
30) Guilherme R, Klein E, Hamid A, Bhatt S, Volleth M, Polityko
A, Kulpanovich A, Dufke A, Albrecht B, Morlot S, Brecevic L,
Petersen M, Manolakos E, Kosyakova N, Liehr T. Human ring
chromosomes - New insights for their clinical significance.
Balkan J Med Genet. 2013;16:13-20.
31) Siragusa M, Lentini M, Schepis C. Agminated lentiginosis in a
patient with ring chromosome 21. Eur J Dermatol. 2012;22:801-3.
32) Arslan M, Yis U, Vurucu S, Tunca Y, Unay B, Akin R. Ring
chromosome 21 in the differential diagnosis of waddling gait.
Brain Dev. 2012;34:792-5.
33) Chen CP, Lin YH, Chou SY, Su YN, Chern SR, Chen YT, Town
DD, Chen WL, Wang W. Mosaic ring chromosome 21, monosomy
21, and isodicentric ring chromosome 21: Prenatal diagnosis,
molecular cytogenetic characterization, and association with
2-Mb deletion of 21q21.1-q21.2 and 5-Mb deletion of 21q22.3.
Taiwan J Obstet Gynecol. 2012;51:71-6.
34) R icher CL, Fitch N, Sitahal S, Murer-Orlando M, Jean P. Analysis
of banding patterns in a case of ring chromosome 21. Am J Med
35) Melnyk AR, Ahmed I, Taylor JC. Prenatal diagnosis of familial
ring 21 chromosome. Prenat Diagn. 1995;15:269-73.