Short Communication
Mosaic tetrasomy 9p at amniocentesis: prenatal diagnosis, molecular cytogenetic
characterization and literature review
Chih-Ping Chen a,b,c,d,e,f *, Liang-Kai Wang a, Schu-Rern Chern b, Peih-Shan Wu g, Yu-Ting Chen b,
Yu-Ling Kuo h, Wen-Lin Chen a, Meng-Shan Lee a and Wayseen Wang b,i
a Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan b Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan
c Department of Biotechnology, Asia University, Taichung, Taiwan
d School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung,
Taiwan
e Institute of Clinical and Community Health Nursing, National Yang-Ming University, Taipei,
Taiwan
f Department of Obstetrics and Gynecology, School of Medicine, National Yang-Ming University,
Taipei, Taiwan
g Gene Biodesign Co. Ltd, Taipei, Taiwan
h Department of Obstetrics and Gynecology, Kaohsiung Medical University Hospital, Kaohsiung
Medical University, Kaohsiung, Taiwan
i Department of Bioengineering, Tatung University, Taipei, Taiwan
* Correspondence to: Chih-Ping Chen, MD
Department of Obstetrics and Gynecology, Mackay Memorial Hospital 92, Section 2, Chung-Shan North Road, Taipei, Taiwan
Tel: +886-2-25433535; Fax: +886-2-25433642, +886-2-25232448 E-mail: [email protected]
Abstract
Objective: This study is aimed at prenatal diagnosis of mosaic tetrasomy 9p and reviewing the literature.
Materials and methods: A 37-year-old woman underwent amniocentesis at 20 weeks of gestation because of advanced maternal age and fetal ascites. Cytogenetic analysis of cultured amniocytes revealed 21.4% (6/28 colonies) mosaicism for a supernumerary i(9p). Repeat amniocentesis was performed at 23 weeks of gestation. Array comparative genomic hybridization (aCGH), interphase fluorescence in situ hybridization (FISH) and quantitative fluorescent polymerase chain reaction (QF-PCR) were applied on uncultured amniocytes, and conventional cytogenetic analysis was applied on cultured amniocytes.
Results: The aCGH analysis on uncultured amniocytes detected a genomic gain at 9p24.3-9q21.11. Interphase FISH analysis on uncultured amniocytes using a 9p24.3-specific probe RP11-31F19 (spectrum red) showed four red signals in 47.1% (49/104 cells) of uncultured amniocytes. Cytogenetic analysis of cultured amniocytes revealed a karyotype of 47,XX, +idic(9)(pterq21.11::q21.11pter)[4]/46,XX[20] and 16.7% (4/24 colonies) mosaicism for tetrasomy 9p. QF-PCR confirmed a maternal origin of tetrasomy 9p. The pregnancy was terminated, and a malformed fetus was delivered with hydrops fetalis and facial dysmorphism. The fetal blood cells had 32.5% (13/40 cells) mosaicism for tetrasomy 9p. Conclusion: Mosaic tetrasomy 9p at amniocentesis can be associated with fetal ascites and hydrops
fetalis. The mosaic level of tetrasomy 9p may decrease after long-term tissue culture in amniocytes in case of mosaic tetrasomy 9p.
Introduction
Tetrasomy 9p, or supernumerary isochromosome 9p [i(9p)], is a rare chromosome abnormality resulting from a supernumerary isochromosome 9p that may involve the entire 9p only; the entire 9p with part of the heterochromatic region of 9q; or the entire 9p with heterochromatic region of 9q and part of the euchromatic region of 9q [1-2].
Tetrasomy 9p has been characterized by clinical features of intrauterine growth restriction (IUGR), developmental delay, ventriculomegaly, Dandy-Walker malformation facial dysmorphism of a bulbous/beaked nose, hypertelorism, micrognathia, ear malformations, and cleft lip/palate, congenital heart defects, hypoplasia of the digits and nails, joint dislocations, and urogenital abnormalities; and the severity of phenotype associated with tetrasomy 9p is influenced by the size of the isochromosome involved, the degree of mosaicism and the presence of tissue mosaicism [1,3-12].
Prenatal diagnosis of mosaic or non-mosaic tetrasomy 9p is uncommon [1,7-10;13-21]. The frequency of prenatally detected tetrasomy 9p at amniocentesis is estimated to be 0.002% [22]. In a population-based study of 88,965 amniocenteses, Forabosco et al [22] found eight cases with isochromosomes including three cases with i(20q), two cases with i(18p), two cases with i(9p) and one case with i(12p). Here, we present our experience of prenatal diagnosis and molecular genetic analysis of mosaic tetrasomy 9p in a fetus with fetal ascites.
Materials and Methods
Clinical description
A 37-year-old, gravida 3, para 1, woman underwent amniocentesis at 20 weeks of gestation because of advanced maternal age. She was Rh-positive, and maternal blood thalassemia screening excluded thalassemia carrier. Maternal syphilis examination revealed a negative finding. She underwent first-trimester maternal serum screening and fetal nuchal translucency screening, and the results were within the normal limits. The pregnancy was uneventful until 19 weeks of gestation when routine ultrasound examination revealed fetal ascites. Amniocentesis and aspiration of fetal ascites were performed at 20 weeks of gestation. Molecular analyses of congenital infection using fetal ascites excluded the infection of toxoplasma, cytomegalovirus and herpes simplex. Cytogenetic analysis of cultured amniocytes revealed 21.4% (6/28) mosaicism for a supernumerary i(9p). The karyotype was 47,XX,+i(9p)[6]/46,XX[22] derived from 28 colonies of cultured
amniocytes. The woman requested repeated amniocentesis at 23 weeks of gestation. The nature of the supernumerary i(9p) was investigated by array comparative genomic hybridization (aCGH) on uncultured amniocytes. The degree of mosaicism for the supernumerary i(9p) in uncultured amniocytes was investigated by interphase fluorescence in situ hybridization (FISH). The parental origin of the supernumerary i(9p) was investigated by quantitative fluorescent polymerase chain reaction (QF-PCR) assays using uncultured amniocytes. Cytogenetic analysis of cultured amniocytes was also performed at repeated amniocentesis. Level II ultrasound at 24 weeks of gestation revealed IUGR with fetal biometry equivalent to 22 weeks of gestation and hydrops fetalis. The pregnancy was subsequently terminated. The fetal blood was collected for cytogenetic analysis.
Conventional cytogenetic analysis
Routine cytogenetic analysis by G-banding techniques at the 550 bands of resolution was performed. About 20 mL of amniotic fluid was collected, and the sample was subjected to in situ amniocyte culture according to the standard cytogenetic protocol [23]. Parental bloods and fetal blood were collected, and the samples were subjected to lymphocyte culture according to the standard blood cytogenetic protocol [24].
Array-CGH
Whole-genome aCGH on the DNA extracted from uncultured amniocytes was performed using NimbleGen ISCA Plus Cytogenetic Array (Roche NimbleGen, Madison, WI, USA). The NimbleGen ISCA Plus Cytogenetic Array has 630,000 probes and a median resolution of 15-20 kb across the entire genome according to the manufacturer's instruction. The DNA from amniocytes was extracted first. It was done by following the manufacturer's protocol of QIAamp DNA Mini kit (Qiagen, Inc., Valencia, CA, USA). Then, the 0.5μg of the extracted DNA was labeled in Cy5 dye compared with equivalent amount of normal female gDNA (G1521, Promega) labeled in Cy3 dye to perform the aCGH experiment. The experiment was performed according to the procedures recommended from Roche NimbleGen ISCA plus Cytogenetic Array's user guide. The data were finally represented by using Nexus 6.1 (BioDiscovery, Hawthorne, CA, USA).
QF-PCR
QF-PCR analysis was performed by using genomic DNAs extracted from uncultured amniocytes and parental bloods as described elsewhere [25]. Briefly, primers specifically flanking polymorphic
markers on chromosome 9p region such as D9S2149 (9p21.1) and D9S303 (9q21.32) were applied to undertake polymorphic marker analysis and parental origin determination of the supernumerary i(9p).
FISH
Interphase FISH analysis was performed on uncultured amniocytes using a 9p24.3-specific bacterial artificial chromosome (BAC) probe RP11-31F19 (dye: Texas red) (547,217-692,143) and a control 9q34.3-specific BAC probe RP11-417A4 (dye: FITC, green) (140,403,320-140,596,187) [hg 19] according to the standard FISH protocol [26].
Results
Whole-genome aCGH analysis on the DNA extracted from uncultured amniocytes detected a 71.03-Mb duplication at 9p24.3-9q21.11, or arr [hg19] 9p24.3p13.1 (0-40,450,202)3.4, 9p13.1q21.11 (40,576,977-71,026,063)3 (Fig. 1). The log2 ratio of 9p24.3p13.1 duplication was 0.799, and the log2 ratio of 9p13.1q21.11 duplication was 0.585. The duplicated region of 9p24.3-9q21.11 contains 632 genes including 151 OMIM genes. The supernumerary i(9p) involves the entire 9p, the heterochromatic region of 9q and part of 9q21.11 (Fig. 1). Interphase FISH analysis on 104 uncultured amniocytes using the 9p24.3-specific probe (RP11-31F19) (spectrum red) and the 9q34.3-specific probe (RP11-417A4) (spectrum green) showed four red signals and two green signals in 49 uncultured amniocytes, and two red signals and two green signals in 55 uncultured amniocytes, indicating 47.1% (49/104 cells) mosaicism for supernumerary i(9p) in uncultured amniocytes (Fig. 2). Cytogenetic analysis of 24 colonies of cultured amniocytes revealed four colonies with a supernumerary i(9p) and 20 colonies with a normal female karyotype. The karyotype of cultured amniocytes was 47,XX,+idic(9)(pterq21.11::q21.11pter)[4]/46,XX[20] (Fig. 3). Cytogenetic analysis of 40 cultured lymphocytes of fetal blood showed a karyotype of 47,XX,+idic(9)(pterq21.11::q21.11pter)[13]/46,XX[27]. The paternal blood had a karyotype of 46,XY. The maternal blood had a karyotype of 46,XX. QF-PCR analysis on the DNAs extracted from uncultured amniocytes and parental bloods confirmed a maternal origin of the supernumerary i(9p) (Fig. 4). The parents decided to terminate the pregnancy. A 722-g female fetus was delivered with hydrops fetalis, hypertelorism, a bulbous nose, micrognathia and low-set ears.
Application of molecular cytogenetic techniques on uncultured amniocytes to detect discrepancy in chromosome mosaicism between uncultured amniocytes and cultured amniocytes has been well reported [27-29]. Tetrasomy 9p caused by supernumerary i(9p) has been shown to be associated with tissue-limited mosaicism with the supernumerary i(9p) cell line presenting predominantly in the peripheral blood, but with a low-level mosaicism for the abnormal cell line or even a normal cell line in the cultures of chorionic villus sampling, amniotic fluid or skin [1,11,14,16;30-36]. The present case provides evidence for the discrepancy in the supernumerary i(9p) mosaicism level between uncultured amniocytes and cultured amniocytes in prenatally detected mosaic tetrasomy 9p. In the present case, the levels of mosaicism for tetrasomy 9p in cultured amniocytes (first amniocentesis), cultured amniocytes (second amniocentesis), fetal blood and uncultured amniocytes (second amniocentesis) were 21.4%, 16.7%, 32.5% and 47.1%, respectively. The present case shows that the mosaic level may decrease after long-term tissue cultures in amniotic fluid with mosaic tetrasomy 9p. The present case also suggests that uncultured amniocytes can be a useful tool for confirmation of the presence of a true fetal mosaicism, and a correlation of high-level tetrasomy 9p mosaicism of uncultured amniocytes may exist with adverse fetal outcome in the pregnancy with prenatally detected mosaic tetrasomy 9p.
To date, at least 14 cases of prenatally detected mosaic (three cases) and non-mosaic (11 cases) tetrasomy 9p have been reported (Table 1). All of the 11 reported cases with non-mosaic tetrasomy 9p were associated with severe phenotypic abnormalities. Our case adds to the list of prenatal diagnosis of mosaic tetrasomy 9p with fetal abnormalities. Prenatal diagnosis of mosaic tetrasomy 9p is very rare [1,7-8], and all of the three reported cases with mosaic tetrasomy 9p were associated with dysmorphism and abnormalities. Table 1 shows that the male: female sex ratio for tetrasomy 9p is 1 (7 males/7 females), indicating no sex preponderance in tetrasomy 9p. Table 1 also shows that fetuses with tetrasomy 9p may present increased nuchal translucency in the first trimester [19-20] and cystic hygroma in the second trimester [19]. Our case additionally shows that fetal ascites and hydrops fetalis can be a prenatal feature associated with mosaic tetrasomy 9p. Table 1 shows that prenatal ultrasound abnormalities associated with mosaic or non-mosaic tetrasomy 9p include polyhydramnios, oligoydramnios, IUGR, Dandy-Walker variant or malformation, ventriculomegaly, skeletal abnormalities, cleft lip and palate, hydronephrosis and congenital heart defects. In a review of 19 fetuses with tetrasomy 9p, Nakamura-Pereira et al [20] summarized that
the major prenatal ultrasound findings are as in the following: IUGR (58%), ventriculomegaly (58%), genitourinary anomaly (47%), hypoplastic/absent vermis (42%), cleft lip and palate (42%), limb malformations (42%), cardiac anomaly (26%), and polyhydramnios (21%). Our case presented no major structural abnormalities but only fetal ascites and hydrops fetalis.
The present case shows the advantages of application of aCGH and QF-PCR on uncultured amniocytes for rapid detection of the presence of high-level mosaicism for tetrasomy 9p. In the present case, the use of aCGH established the euchromatic content of 9q in the supernumerary i(9p), and the use of QF-PCR established the maternal origin of the supernumerary i(9p). Dutly et al [5] suggested that the supernumerary i(9p) is predominantly caused by maternal meiosis II non-disjunction followed by rearrangements leading to a duplication of 9p and a loss of 9q. The QF-PCR result in our case is consistent with the previous reports that the supernumerary i(9p) is originated from the maternal chromosome 9 [1,8]. Prenatal diagnosis by chorionic villus sampling using cultured chorionic villi cells or by amniocentesis using cultured amniocytes may obtain a false negative result in pregnancies with fetal mosaic tetrasomy 9p because of tissue-limited mosaicism, and a selective disadvantage for the abnormal cell line with the supernumerary i(9p) during cell culture [11,34-36]. For example, Grass et al [34] reported 75% mosaicism for tetrasomy 9p in blood cells in a boy with mild manifestations but a normal karyotype of 46,XY at chorionic villus sampling. Eggermann et al [35] reported 32% mosaicism for tetrasomy 9p in blood cells in a girl with multiple abnormalities but a normal karyotype of 46,XX at amniocentesis. In this regard, application of molecular cytogenetic techniques such as aCGH, QF-PCR and interphase FISH on uncultured amniocytes is very practical for confirmation and diagnosis of mosaic tetrasomy 9p at repeated amniocentesis. Chen et al [1] suggested that fetal blood sampling is valuable for prenatal confirmation of low-level mosaic tetrasomy 9p detected prenatally by amniocentesis. Shehab et al [36] suggested that tetrasomy 9p is well tolerated in lymphocytes, and the supernumerary i(9p) is often found in all or a very high frequency of blood cells. Our finding of 32.5% mosaicism for tetrasomy 9p in cultured fetal blood lymphocytes is in accordance with the previous observations. This report provides evidence for the nature of decrease in mosaic level of mosaic tetrasomy 9p in cultured amniocytes after long-term culture and may explain the previous observations of possible false-negative diagnosis of mosaic tetrasomy 9p by amniocentesis or chorionic villus sampling. Recently, aCGH application on uncultured amniocytes for rapid diagnosis of aneuploidy has been
possible, and it may has the advantage of detection of mosaic tetrasomy 9p without the influence of long-term culture effect on amniocytes.
In summary, we report prenatal diagnosis and molecular genetic analysis of mosaic tetrasomy 9p at amniocentesis associated with fetal ascites and hydrops fetalis. We have observed discrepancy of the mosaic levels between uncultured amniocytes and cultured amniocytes, and suggest that the mosaic level of tetrasomy 9p may decrease after long-term tissue culture in amniocytes in case of mosaic tetrasomy 9p.
Acknowledgements
This work was supported by research grants NSC-99-2628-B-195-001-MY3 and NSC-101-2314-B-195-011-MY3 from the National Science Council and MMH-E-102-04 from Mackay Memorial Hospital, Taipei, Taiwan.
References
1. Chen C-P, Chang T-Y, Chern S-R, Lee C-C, Town D-D, Lee M-S, et al. Prenatal diagnosis of low-level mosaic tetrasomy 9p by amniocentesis. Prenat Diagn 2007; 27: 383-5.
2. Chen C-P, Lin S-Y, Su J-W, Lee M-S, Wang W. Phenotypic features associated with mosaic tetrasomy 9p in a 20-year-old female patient include autism spectrum disorder. Genet Couns 2012; 23: 335-8. 3. Melaragno MI, Brunoni D, Patrícia FR, Corbani M, Mustacchi Z, dos Santos Rde C, et al. A patient with
tetrasomy 9p, Dandy-Walker cyst and Hirchsprung disease. Ann Génét 1992; 35: 79-84.
4. Tonk VS. Moving towards a syndrome: A review of 20 cases and a new case of non-mosaic tetrasomy 9p with long-term survival. Clin Genet 1997; 52: 23-9.
5. Dutly F, Balmer D, Baumer A, Binkert F, Schizel A. Isochromosomes 12p and 9p: parental origin and possible mechanisms of formation. Eur J Hum Genet 1998; 6: 140-4.
6. Stumm M, Tönnies H, Mandon U, Götze A, Krebs P, Wieacker PF. Mosaic tetrasomy 9p in a girl with multiple congenital anomalies: cytogenetic and molecular-cytogenetic studies. Eur J Pediatr 1999; 158: 571-5.
7. Dhandha S, Hogge WA, Surti U, McPherson E. Three cases of tetrasomy 9p. Am J Med Genet 2002; 113: 375-80.
8. Cazorla Calleja MR, Verdu A, Felix V. Dandy-Walker malformation in an infant with tetrasomy 9p. Brain Dev 2003; 25: 220-3.
9. Deurloo KL, Cobben JM, Heins YM, de Ru M, Wijnaendts LCD, van Vugt JMG. Prenatal diagnosis of tetrasomy 9p in a 19-week-old fetus with Dandy-Walker malformation: a case report. Prenat Diagn 2004; 24: 796-8.
10.Hengstschläger M, Bettelheim D, Drahonsky R, Repa C, Deutinger J, Bernaschek G. Prenatal diagnosis of tetrasomy 9p with Dandy-Walker malformation. Prenat Diagn 2004; 24: 623-6.
11.Lloveras E, Pérez C, Solé F, Zamora L, Lladonosa A, Espinet B, et al. Two cases of tetrasomy 9p syndrome with tissue limited mosaicism. Am J Med Genet 2004; 124A: 402-6.
12.McAuliffe F, Winsor EJT, Chitayat D. Tetrasomy 9p mosaicism associated with a normal phenotype. Fetal Diagn Ther 2005; 20: 219-22.
13.McDowall AA, Blunt S, Berry AC, Fensom AH. Prenatal diagnosis of a case of tetrasomy 9p. Prenat Diagn 1989; 9: 809-11.
14.Schaefer GB, Domek DB, Morgan MA, Muneer RS, Johnson SF. Tetrasomy of the short arm of chromosome 9: Prenatal diagnosis and further delineation of the phenotype. Am J Med Genet 1991; 38: 612-5.
15.Van Hove J, Kleczkowska A, De Bruyn M, Bekaert J, Fryns JP. Tetrasomy 9p: prenatal diagnosis and fetopathological findings in a second trimester male fetus. Ann Génét 1994; 37: 139-42.
16.Pertile MD, Ryan JT, Kelley JL, Webber LM. Prenatal diagnosis of tetrasomy 9p. Bull Hum Genet Soc Australasia 1996; 9: 43.
17.Tang W, Wenger SL, Boyd BK, Hummel M. Prenatal diagnosis of tetrasomy 9p. Am J Med Genet 2004; 126A: 328.
18.Tan Y-Q, Chen X-M, Hu L, Guan X-Y, Lu G-X. Prenatal diagnosis of nonmosaic tetrasomy 9p by microdissection and FISH: case report. Chin Med J (Engl) 2007; 120: 1281-3.
19.di Vera E, Liberati M, Celentano C, Calabrese G, Guanciali-Franchi PE, Morizio E, et al. Rhombencephalosynapsis in a severely polymalformed fetus with non-mosaic tetrasomy 9p, in intracytoplasmic-sperm-injection pregnancy. J Assist Reprod Genet 2008; 25: 577-80.
20.Nakamura-Pereira M, do Cima LC, Llerena JC Jr, Guerra FAR, Peixoto-Filho FM. Sonographic findings in a case of tetrasomy 9p associated with increased nuchal translucency and Dandy-Walker malformation. J Clin Ultrasound 2009; 37: 471-4.
21.Podolsky R, Saltzman D, Auerbach M, Roman AS. Absent nasal bone as a marker of tetrasomy 9p. Prenat Diagn 2011; 31: 1313.
22.Forabosco A, Percesepe A, Santucci S. Incidence of non-age-dependent chromosomal abnormalities: a population-based study on 88965 amniocenteses. Eur J Hum Genet 2009; 17: 897-903.
23.Peakman DC. Amniotic fluid II: in situ culture and harvesting: coverslip processing method. In: Barch MJ, ed. The ACT Cytogenetic Laboratory Manual, 2nd edn. New York: Roven Press; 1991. p.172-5.
24.Jenks H, Taplett J. PHA-stimulated peripheral blood culture I. In: Barch MJ, ed. The ACT Cytogenetic Laboratory Manual, 2nd edn. New York: Roven Press; 1991. p.24-6.
25.Chen C-P, Chern S-R, Wang W. Rapid determination of zygosity and common aneuploidies from amniotic fluid cells using quantitative fluorescent polymerase chain reaction following genetic amniocentesis in multiple pregnancies. Hum Reprod 2000; 15: 929-34.
26.Dyer K, Meyne J. Amniotic fluid II: in situ culture and harvesting: coverslip processing method. In: Barch MJ, ed. The ACT Cytogenetic Laboratory Manual, 2nd edn. New York: Roven Press;1991. p.172-5.
27.Chen C-P, Su Y-N, Lin S-Y, Chern S-R, Chen Y-T, Lee M-S, et al. Prenatal diagnosis of mosaic trisomy 2: Discrepancy between molecular cytogenetic analyses of uncultured amniocytes and karyotyping of cultured amniocytes in a pregnancy with severe fetal intrauterine growth restriction. Taiwan J Obstet Gynecol 2011; 50: 390-3.
28.Chen C-P,Su Y-N, Chern S-R, Chen Y-T, Wu P-S, Su J-W, et al. Mosaic trisomy 2 at amniocentesis: prenatal diagnosis and molecular genetic analysis. Taiwan J Obstet Gynecol 2012; 51: 603-11.
29.Chen C-P, Cheng S-D, Chueh H-Y, Su Y-N, Chern S-R, Su J-W, et al. Discrepancy in the trisomy mosaicism level between cultured amniocytes and uncultured amniocytes in prenatally detected mosaic trisomy 20. Taiwan J Obstet Gynecol 2013; 52: 145-6.
30.Orye E, Verhaaren H, Van Egmond H, Devloo-Blancquaert A. A new case of the trisomy 9p syndrome. Report of a patient with unusual chromosome findings (46,XX/47,XX,+i(9p)) and a peculiar congenital heart defect. Clin Genet 1975; 7: 134-43.
31.Cuoco C, Gimelli G, Pasquali F, Poloni L, Zuffardi O, Alicanta P, et al. Duplication of the short arm of chromosome 9. Analysis of five cases. Hum Genet 1982; 61: 3-7.
32.Calvieri F, Tozzi C, Benincori C, DeMeurulis M, Bellussi A, Genuardi M, et al. Partial tetrasomy 9p in an infant with clinical and radiological evidence for multiple joint dislocations. Eur J Pediatr 1988; 147: 645-8.
33.Papenhausen P, Riscile G, Miller K, Kousseff B, Tedesco T. Tissue limited mosaicism in a patient with tetrasomy 9p. Am J Med Genet 1990; 37: 388-91.
34.Grass FS, Parke JC Jr, Kirkman HN, Christensen V, Roddey OF, Wade RV, et al. Tetrasomy 9p: tissue-limited idic(9p) in a child with mild manifestations and a normal CVS result. Report and review. Am J Med Genet 1993; 47: 812-6.
35.Eggermann T, Rossier E, Theurer-Mainka U, Backsch C, Klein-Vogler U, Enders H, et al. New case of mosaic tetrasomy 9p with additional neurometabolic findings. Am J Med Genet 1998; 75: 530-3.
36.Shehab MI, Mazen I, Bint S. Tissue-specific mosaicism for tetrasomy 9p uncovered by array CGH. Am J Med Genet 2011; 155A: 2496-500.
Figure Legends
Fig. 1. Whole-genome array comparative genomic hybridization analysis on uncultured amniocytes shows a 71.03-Mb duplication at 9p24.3-q21.11, or arr [hg19] 9p24.3p13.1 (0-40,450,202)3.4, 9p13.1q21.11 (40,576,977-70,026,063)3. The log2 ratio of 9p24.3p13.1 duplication is 0.799. The log2 ratio of 9p13.1q21.11 duplication is 0.585. (A) Whole genome view, (B) chromosomal view and (C) zoom-in view. The arrows indicate the duplicated region of chromosome 9.
Fig. 2. Interphase fluorescence in situ hybridization analysis on uncultured amniocytes using the 9p24.3-specific probe RP11-31F19 (spectrum red) and the 9q34.3-9p24.3-specific probe RP11-417A4 (spectrum green) shows (A) two red signals and two green signals in a normal uncultured amniocyte and (B) four red signals (arrows) and two green signals in an abnormal uncultured amniocyte with tetrasomy 9p.
Fig. 3. A karyotype of 47,XY,+idic(9)(pterq21.11::q21.11pter).
Fig. 4. Representative electrophoretogram of quantitative fluorescent polymerase chain reaction analysis at short tandem repeat markers specific for chromosome 9. The marker D9S2149 (9p21.1) shows two different parental alleles with a 3:1 (maternal: paternal) gene dosage increase in the maternal allele, indicating a maternal origin of the supernumerary isochromosome 9p.
Table 1. Reported cases of mosaic or non-mosaic tetrasomy 9p detected by amniocentesis, cordocentesis or chorionic villus sampling
Authors Cases Indication Prenatal diagnosis Confirmatory studies Outcome and phenotype McDowall et al [13]
47,XY,+i(9p) Abnormal ultrasound
Amniocentesis: +i(9p)=100%
No Ultrasound: ventriculomegaly, agenesis of the corpus callosum, an enlarged cisterna magna. TOP; abnormal fetus: facial dysmorphism, neck edema, cleft lip and palate.
Schaefer et al [14]
47,XY,+i(9p) Abnormal
ultrasound Cordocentesis:+i(9p)=100% (25 cells) Skin: +i(9p)=100% (25 cells) Ultrasound: IUGR, severe oligohydramnios, absent kidneys and bladder, hydrocephalus. Delivery at 34 w, 1510 g, neonatal death, facial dysmorphism, bilateral cleft lip and palate, multiple joint deformities, micropenis, cryptorchidism, lissencephaly, agenesis of the corpus callosum.
Van Hove et al [15]
47,XY,+i(9p) Abnormal
ultrasound Amniocentesis:+i(9p)=100% (22 cells) No Ultrasound: hydrocephalus, bilateral cleft lip and palate, complex cardiac defect, bilateral hydronephrosis, complex limb malformation. TOP; abnormal fetus: facial dysmorphism, hypoplastic penis and scrotum, single umbilical artery, DORV, VSD, hypoplastic bilateral ventricle.
Dhandha et al [7]
Case 1 47,XX,+i(9p) Abnormal
ultrasound Amniocentesis:+i(9p)=100% Cord blood: +i(9p)=100%Lung: +i(9p)=100% Placenta: +i(9p)=100%
Ultrasound: IUGR, cleft lip, ventriculomegaly, Dandy-Walker variant, neonatal death, facial dysmorphism, bilateral cleft lip and palate, elbow flexion contractures, knee hyperextension, abnormal digits, congenital heart defects.
Case 2 47,XX,+i(9p)/46,XX AMA, Abnormal ultrasound
Amniocentesis:
+i(9p)=96.3% (27 colonies) No Ultrasound: bilateral cleft lip, hypoplastic left ventricle, VSD, echogenic kidneys, short hands and fingers. Delivery at 37 w, 1805 g, facial dysmorphism, short digits, clinodactyly, congenital heart defects. Cazorla Calleja et al [8]
47,XX,+i(9p)/46,XX Abnormal
ultrasound Amniocentesis:+i(9p)=50% (50 cells) Cordocentesis: +i(9p)=25%
Peripheral blood: +i(9p)=75.3% (89 cells) Polymorphic DNA markers: maternal origin of +i(9p)
Ultrasound: IUGR, ventriculomegaly. Delivery at 39 w, trigonocephaly, left eye enophthalmos, facial
dysmorphism, bilateral hydronephrosis, mega cisterna magna, hydrocephalus, psychomotor developmental delay at age 4 y.
47,XX,+i(9p) AMA, Abnormal ultrasound CVS: +i(9p)=100% Amniocentesis: +i(9p)=100%
No Ultrasound: Dandy-Walker malformation,
ventriculomegaly, dilation of renal pelves. TOP; abnormal fetus: facial dysmorphism.
Hengstschläger et al [10]
47,XY,+i(9p) Abnormal
ultrasound CVS: +i(9p)=100%Amniocentesis: +i(9p)=100%
No Ultrasound: abnormal head, Dandy-Walker malformation, clubfeet, polyhydramnios, facial dysmorphism, left rotated heart, VSD, an overriding aorta. TOP; abnormal fetus.
Tang et al [17]
47,XX,+i(9p) Abnormal
ultrasound Amniocentesis:+i(9p)=100% (20 cells) Blood: +i(9p)=95% (20 cells)Cord: +i(9p)=85% (20 cells) Ultrasound: abnormal skull, ventriculomegaly, clubfeet, cleft lip and palate. Delivery at 35 w, 1730 g, Dandy-Walker variant, agenesis of the corpus callosum, horseshoe kidney.
Chen et al [1]
47,XX,+i(9p)/46,XX AMA Amniocentesis:
+i(9p)=20% (20 colonies) Retap:
+i(9p)=16.7% (24 colonies)
Skin: +i(9p)=0% (40 cells) Lung: +i(9p)=0% (40 cells) Cord blood: +i(9p)=48% (40 cells) Polymorphic DNA markers: maternal origin of +i(9p)
TOP; abnormal fetus: facial dysmorphism.
Tan et al [18]
47,XY,+i(9p) Abnormal
ultrasound Amniocentesis:+i(9p)=100% (30 cells) No Ultrasound: IUGR, polyhydramnios, cleft lip and palate, facial dysmorphism. TOP; abnormal fetus: hypoplastic nails, clinodactyly, clubfeet.
di Vera et al [19] 47,XY,+i(9p) AMA, Abnormal ultrasound, increased NT Amniocentesis: +i(9p)=100%
No Ultrasound: increased NT in the first trimester, oligohydramnios, Dandy-Walker malformation, IUGR, micromelia, brachydactyly, rocker-bottom feet, horseshoe kidney, AVSD, bilateral cleft lip and palate, cystic hygroma, ventriculomegaly. TOP; abnormal fetus: rombencephalosynapsis. Nakamura-Pereira et al [20] 47,XY,+i(9p) Abnormal ultrasound, increased NT Amniocentesis:
+i(9p)=100% (50 cells) No Ultrasound: increased NT (2.9 mm) in the first trimester, subcutaneous edema, clubfeet, hyperechoic kidneys, bilateral pelvic dilation, Dandy-Walker malformation, retrognatism, cleft lip and palate, arthrogryposis. Delivery at 30 w, 1120 g, facial dysmorphism, cryptorchidism, micropenis, neonatal death. Podolsky et al [21]
47,+i(9p) AMA, Abnormal ultrasound
CVS: +i(9p)=100% No Ultrasound: absent nasal bone.
Present case 47,XX,+i(9p)/46,XX AMA, Abnormal ultrasound Amniocentesis: +i(9p)=21.4% (28 colonies) Retap: +i(9p)=16.7% (24 colonies) Interphase FISH on uncultured amniocytes: +i(9p)=47.1% (104 cells) aCGH on uncultured amniocytes: duplication of 9p24.3-q21.11 QF-PCR on uncultured amniocytes: maternal origin of +i(9p)
Fetal blood:
+i(9p)=32.5% (40 cells) Ultrasound: fetal ascites, hydrops fetalis, IUGR. TOP; abnormal fetus: facial dysmorphism.
i(9p): isochromosome 9p, CVS:chorionic villus sampling, IUGR: intrauterine growth restriction, DORV: double outlet of the right ventricle, VSD: ventricular septal defect, TOP: termination of pregnancy, AMA: advanced maternal age, w: weeks, y: years, NT: nuchal translucency, AVSD: atrioventricular septal defect, FISH: fluorescence in situ hybridization, aCGH: array comparative genomic hybridization, QF-PCR: quantitative fluorescent polymerase chain reaction.
