Prenatal diagnosis of trisomy 9. Six cases and a review of the literature

Case report: A case report and literature review of complete trisomy 9

Complete trisomy 9 is a rare and lethal chromosomal anomaly characterized by multisystem dysmorphism and central nervous system (CNS) malformations. This study presents a case of complete trisomy 9 with an unusual phenotypic association and investigates the genetic pathways involved in this chromosomal abnormality. Trisomy 9 leads to a wide range of organ abnormalities, and this research contributes to a better understanding of the phenotype associated with this rare aneuploidy. The literature on the phenotypes of fetuses with various systems affected by complete trisomy 9 was reviewed and summarized. Correct diagnosis and appropriate counseling based on the characteristics of previous reports of fetuses with trisomy 9 is essential in maternity care and clinical management. To provide guidance and help for clinical diagnosis, this study aimed to explore the clinical and genetic characteristics of trisomy 9 syndrome to improve clinicians' understanding of the disease.

Trisomy 9 mosaic syndrome: Sixteen additional patients with new and/or less commonly reported features, literature review, and suggested clinical guidelines

Trisomy 9 mosaic syndrome (T9M) is a rare condition characterized by multiorgan system involvement including craniofacial dysmorphisms, cardiac, genitourinary (GU), skeletal, and central nervous system (CNS) abnormalities. Although more than 100 cases have been reported in the literature, a comprehensive review has not been performed nor have clinical guidelines been established. Therefore, we describe the clinical features of 16 additional patients, review features of previously reported individuals, and suggest clinical guidelines. Our findings expand the clinical phenotype of T9M, including novel features of amblyopia, astigmatism, corectopia of pupil, posterior embryotoxon, and diaphragmatic eventration. Most patients had prenatal and perinatal issues, particularly from respiratory, growth, and feeding standpoints. Although small birth parameters were common, long-term growth trends varied widely. An association with advanced parental ages was also identified. The spectrum of growth and development was wide, ranging from nonverbal patients to those able to participate in educational programs with age-appropriate peers. The severity of clinical outcomes was unrelated to blood lymphocyte mosaicism levels. Microarray analysis had a higher diagnostic rate compared to standard karyotype analysis and should be utilized if this diagnosis is suspected. Future longitudinal studies will be key to monitor long-term outcomes of individuals with T9M and determine best practices for clinical management.

Partial trisomy 9 (9pter->9q22.1) and partial monosomy 14 (14pter- >14q11.2) due to paternal translocation t(9;14)(q22.1;q11.2) in a case of Dysmorphic features

Trisomy 9 including mosaic and partial trisomy is less frequently seen chromosomal abnormality in live born children. The pure or partial trisomy 9 frequently been reported in prenatal diagnosis and product of conception. However few studies reported partial trisomy 9 in live born children. In addition data on genotype and phenotype correlation of partial trisomy is not well understood except few case reports. Here we report a case of partial trisomy 9 and monosomy 14 with a 46,XY,der(9)t(9;14)(q22.1;q11.2)pat,-14 karyotype in a 5-year old dysmorphic child. The proband was confirmed as trisomic for 9pter->9q22.1 and monosomic for 14pter->q11.2 due to paternal t(9;14)(q22.1;q11.2) balanced translocation using a combination of conventional and molecular cytogenetic (fluorescence in situ hybridization, array-comparative genomic hybridization) techniques. The clinical features similar to pure trisomy 9 is due to duplication of the large region of chromosome 9. However, the present report of partial trisomy 9 and monosomy 14 is a novel case report and showing comparatively longer survival which have not been previously reported in the literature. The parent of the proband was counseled for the future pregnancies.

Partial trisomy 9: prenatal diagnosis and recurrence within same family

Trisomy 9 can be suspected and confirmed in the prenatal period since the 11–13.6 weeks of screening. In cases of partial trisomy 9, the diagnosis is important especially to counseling the couple due to the increased likelihood of recurrence in subsequent pregnancies.

Report of a Case with Trisomy 9 Mosaicism

Trisomy 9 is a rare chromosome disorder with high neonatal mortality. It is often seen in mosaic form. Most patients who survive are severely mentally retarded. The main features of this syndrome are "bulbous" nose, microphthalmia, dislocated limbs, and other anomalies of skeletal, cardiac, genitourinary, and central nervous system. Most patients have developmental and cognitive impairment. Patients with mosaicism survive longer than non-mosaics, but it was believed that the degree of mosaicism in lymphocytes or fibroblasts does not associate with survival or degree of impairment. In this report, we present a 2.5-year-old male case of mosaic trisomy 9, to show the wide range of clinical findings in this chromosome disorder. The patient had cardiac anomalies, inguinal hernia, and undescendent testes. He had low-set slightly malformed ears, deeply-set malformed eyes, small palpebral fissures, micrognathia, developmental delay and unilateral optic hypoplasia. The most prominent facial anomaly in this patient was eye anomalies. Cytogenetic analysis with G banding showed karyotype 47XY,+9 in 44% of peripheral lymphocytes examined (47XY,+9[22], 46XY[28]). His parents' karyotypes were normal. Moderate developmental delay, which was detected in this patient shows that the range of motor and cognitive impairment in this chromosomal disorder is quite broad. This fact should be considered in genetic counseling as well as prenatal diagnosis of this chromosomal disorder.

Ultrasound diagnosis of central nervous system anomalies (bifid choroid plexus, ventriculomegaly, Dandy-Walker malformation) associated with multicystic dysplastic kidney disease in a trisomy 9 fetus: case report with literature review

Trisomy 9 is a lethal chromosomal abnormality that rarely progresses beyond the second trimester of pregnancy. Multiple central nervous system anomalies, including bifid choroid plexus, ventriculomegaly, and Dandy-Walker malformation, associated with multicystic dysplastic kidney disease in a trisomy 9 fetus are reported. The prenatal ultrasound diagnosis has been aided by novel three-dimensional ultrasound software.

Mosaic trisomy 9 at amniocentesis: prenatal diagnosis and molecular genetic analyses

OBJECTIVE

To present prenatal diagnosis and molecular genetic analyses of mosaic trisomy 9.

MATERIALS, METHODS AND RESULTS

A 35-year-old woman, gravida 3, para 1, underwent amniocentesis at 17 weeks of gestation because of her advanced maternal age. Amniocentesis revealed a karyotype of 47,XX,+9[3]/46,XX[6]. Repeat amniocentesis at 19 weeks of gestation revealed a karyotype of 47,XX,+9[6]/46,XX[19]. At 22 weeks of gestation, she was referred to a tertiary medical center for genetic counseling, and amniocentesis revealed a karyotype of 47,XX,+9[2]/46,XX[22]. Array comparative genomic hybridization analysis of uncultured amniocytes revealed no genomic imbalance in chromosome 9. However, interphase fluorescence in situ hybridization analysis of uncultured amniocytes showed that nine (18%) of 50 cells were trisomic for chromosome 9. Polymorphic DNA marker analyses also revealed a diallelic pattern with unequal biparental inheritance of chromosome 9 and a dosage ratio of 1:18 (paternal allele:maternal allele) in the uncultured amniocytes and a dosage ratio of 1:36 in the cultured amniocytes, indicating that the euploid cell line had maternal uniparental isodisomy for chromosome 9. Level II ultrasound demonstrated bilateral ventriculomegaly. The pregnancy was subsequently terminated, and a malformed fetus was delivered. Postnatal cytogenetic and polymorphic DNA marker analyses of the fetal and extraembryonic tissues confirmed the prenatal diagnosis.

CONCLUSION

Mosaic trisomy 9 carries a high risk of fetal abnormalities warranting detailed sonographic investigation of congenital malformations. Mosaic trisomy 9 can be associated with maternal uniparental disomy for chromosome 9 in euploid cell lines. Array comparative genomic hybridization is limited for the detection of low-level mosaicism.

Trisomy 9 mosaicism diagnosed in utero

We present three cases of trisomy 9 mosaicism diagnosed by amniocentesis with ongoing pregnancies after referral to our center due to fetal abnormalities. Two cases were associated with severe fetal growth restriction (FGR), each of which resulted in an intrauterine fetal demise (IUFD) in the third trimester. The other case involved mild FGR with a congenital diaphragmatic hernia and resulted in a live birth with severe development delay. A major prenatal finding of trisomy 9 mosaicism is FGR. Fetuses with trisomy 9 mosaicism can rarely survive in the case of severe FGR.

Antenatal detection of mosaic trisomy 9 by ultrasound: a case report and literature review

This paper presents a fetus with mosaic trisomy 9 diagnosed by chorionic villus sampling and confirmed by cordocentesis, and compares this case with published cases in order better to define the ultrasound markers confined to trisomy 9 syndrome. Detailed fetal ultrasound examination was carried out, revealing shortened femur, placental cysts and oligohydramnios. All published trisomy 9 cases with abnormal ultrasound findings were extracted from the MEDLINE database in the period from 1973 to 2002. We found 12 non-mosaic and 13 mosaic cases, including our case. The most frequent ultrasound abnormalities included characteristic cardiac, skeletal, craniofacial and central nervous system malformations. Intrauterine growth restriction and single umbilical artery were prevalent non-specific findings in both non-mosaic and mosaic groups. Parental chromosomal variations, as in our case, were not uncommon findings. When a fetus shows structural anomalies suggesting the presence of trisomy 9, karyotyping should be performed on both chorionic villi or amniocytes and fetal blood lymphocytes to enable a correct diagnosis to be made.

Ultrasound manifestations of unusual trisomies-excluding trisomy 13, 18, and 21: a literature review

Trisomy is the most commonly identified chromosome abnormality, occurring in at least 4% of all clinically recognized pregnancies (1). Most of the trisomies are associated with a single additional chromosome, although 2 other types of trisomic conceptions are occasionally observed, those with 2 additional chromosomes or double trisomy and those with both a normal and trisomic cell line or mosaic trisomies. The adverse effects of trisomy on the phenotype are well established. In this review article, we consider the prevalence of the unusual trisomies (excluding 13, 18, and 21) and present a review of their ultrasound findings.

[Mosaic trisomy 9: report of a new case with a long-term survival]

INTRODUCTION

Trisomy 9 is an uncommon chromosome abnormality that may be seen in a mosaic or non-mosaic state.

OBJECTIVE

To better define the phenotype and prognosis of this disorder we report a new case of mosaic trisomy 9 with a long-term survival.

CLINICAL REPORT

We present the case of a female patient, born from the first pregnancy of a healthy couple. Fetal ultrasounds disclosed intrauterine growth retardation and oligohydramnios. Cesarean section was performed in the 34th week. Birth weight was 1,478 g. Neonatal examination showed: dolichocephaly; hypotelorism, microphthalmia, short palpebral fissures; broad-based nose with bulbous tip; micrognathia; low-set malformed ears; abnormal hands and feet; no other malformations. The initial karyotype determination was normal (46,XX). At 17 months of age, a second karyotype was requested because the patient developed severe psychomotor retardation. Chromosome analysis showed mosaic trisomy 9 (46,XX/47,XX, + 9). Six months later, a single upper central incisor was noted. To our knowledge, this feature has not been reported previously in the trisomy 9. The patient is now 4 years old. She shows severe psychomotor retardation, but no other complications.

COMMENTS

It is important to be aware of the possibility that mosaicism may exist in a patient with normal blood karyotype and abnormal phenotype. We conclude that a great number of cells is needed in order to obtain a correct karyotype diagnosis. Correct diagnosis is essential to define the prognosis and provide accurate genetic counselling.

Pathological findings in the complete trisomy 9 syndrome: three case reports and review of the literature

The term "complete trisomy 9" is used to indicate trisomy of the entire chromosome 9 without evidence of mosaicisms. It is a relatively rare chromosomal abnormality because the vast majority of affected pregnancies result in 1st trimester spontaneous abortions. The purpose of this paper is to delineate the complete trisomy 9 syndrome, based on autopsy findings. We performed an exhaustive review of the literature of complete forms of this trisomy with autopsy examination and added 3 new cases from our center with new findings not previously described.

Prenatal diagnosis of trisomy 9

Fetal trisomy 9, especially its nonmosaic form, is a rare chromosomal abnormality and there are only 8 cases reported to have been sonographically detected in the prenatal period. We report a case of nonmosaic fetal trisomy 9, mimicking trisomy 13 on sonographic findings at 32 weeks' gestation. Although the incidence of trisomy 9 is rare, diagnosing trisomy 9 is important because the sonographic features are similar to those of trisomies 13 and 18, and cannot to be identified by routine fluorescencein situ hybridization. Because nonmosaic trisomy 9 is universally lethal, correct diagnosis and appropriate counseling is essential in patient care and clinical management.

Prenatal ultrasound findings in complete trisomy 9

OBJECTIVE

To report on the prenatal ultrasound findings associated with complete trisomy 9.

METHODS

Cases of complete trisomy 9 diagnosed prenatally were identified by reviewing the reports from two large cytogenetics laboratories serving tertiary referral centers for prenatal diagnosis. Information on prenatal ultrasound findings and outcome was obtained in all cases.

RESULTS

Nine cases of complete trisomy 9 were identified. The diagnosis was made in the first trimester in four cases, in the second trimester in three and in the third trimester in two. Two fetuses underwent first-trimester ultrasound screening for aneuploidy and the nuchal translucency thickness was increased in both. All five fetuses detected in the second and third trimesters had several fetal anomalies including Dandy-Walker malformation in four cases, facial dysmorphism in four, genitourinary anomalies in three, congenital heart defects in three, ventriculomegaly in three, abnormal hands in two and megacisterna magna in one. Four fetuses were growth-restricted at the time of ultrasound evaluation. However, the two cases diagnosed in the third trimester had routine second-trimester anomaly scans reported as normal. There were no survivors in this series.

CONCLUSION

Fetuses with complete trisomy 9 have multiple anomalies that can be readily detected prenatally by ultrasound. These mainly include, but are not restricted to, craniofacial, cardiovascular, musculoskeletal and genitourinary malformations. However, findings can be subtle and therefore missed at the routine second-trimester scan.

Feasibility, accuracy and safety of chorionic villus sampling: a report of 10741 cases

OBJECTIVES

To evaluate the feasibility, accuracy and safety of chorionic villus sampling (CVS).

METHODS

Ten thousand seven hundred and forty one singleton pregnancies at risk of chromosome abnormalities (96.3%) and gene disorders (2.8%) were referred from 1990 to 1999 to the fetal medicine unit of a teaching hospital. CVS was performed transabdominally after 11 weeks, using a modified freehand ultrasonographically guided technique by 5 operators. Fetal karyotyping was obtained using a direct method before 1995 and was completed by cell culture after 1996. Failed results, feto-placental discrepancy and fetal loss were assessed.

RESULTS

Villi were sampled using extra-amniotic puncture (89.4%) and one sampling-device insertion (92.3%). The mean weight of the specimen was 15.2 +/- 6.0 mg. All attempts at sampling were successful, except eight (0.07%). The number of failed results following direct preparation, cell culture and both methods was 20 (0.19%), 23 (0.21%) and 2 (0.02%), respectively. Light maternal cell contamination occurred in less than 1% of the samplings after microscopic selection of the villi, and never interfered with the assessment of karyotyping. All 3 false-negative results (0.03%) were recorded after direct preparation and 2 were corrected by culture. The rate of chromosomal abnormalities confined to the placenta decreased from 1.08% before 1995 to 0.73% after 1996. True fetal mosaicisms were recorded in 7 cases (0.06%). The rate of fetal loss at <28 weeks was 1.64% in all pregnancies and 1.92% when CVS was performed before 13 weeks. Advanced maternal age was the single factor significantly associated with fetal loss.

CONCLUSIONS

CVS was feasible, accurate and safe in our institution, as a result of the increasing experience of the operators and the cytogeneticists.

Mosaic trisomy 9 and lobar holoprosencephaly

The main features of trisomy 9 syndrome in mosaic and non-mosaic forms have been thoroughly described. Characteristic traits are low-set malformed ears, micrognathia, broad nose with bulbous tip, abnormal brain, congenital heart defects, abnormal hands and feet, genital abnormalities, and early death. We report a case of mosaic trisomy 9 with holoprosencephaly (HPE). The propositi was born at 37 weeks, with intra-uterine growth retardation, hypotelorism and single nostril, ventricular septal defect, anterior placement of anus, clenched hands with thumb adduction and ulnar deviation. Facial anomalies characteristic of trisomy 9 included deeply set eyes and short palpebral fissures, flat face with maxillary hypoplasia, small mouth, and low-set posteriorly angulated ears. Cytogenetic analysis showed mosaic trisomy 9 with 17% trisomic cells. Pathology confirmed lobar HPE. In literature, isolated arrhinia, related to the HPE spectrum, was reported in one case of mosaic trisomy 9. Our case raises the question of the causative role of trisomy 9 in full blown HPE.

Insulin-like growth factor serum concentrations reflect insufficient growth in a hypoplastic infant with partial trisomy 9q in the 12th week of life

This report presents changes of IGFs and IGFBPs in a female infant with partial trisomy 9q in the 12th week of life. Studying deficient growth in this hypoplastic infant (birth weight 1405 g, birth length 36 cm) with dysmorphic features, the following changes in IGFs and IGFBPs were detected (microg/l): IGF-I: 26.5 vs 48.1 in healthy infants; IGF-II: 420 vs 728; IGFBP-2: 931 vs 524; IGFBP-3: 800 vs 1070. This demonstrates that IGFs and IGFBPs may reflect individual insufficient growth even at this early age.

Confined placental mosaicism for trisomies 2, 3, 7, 8, 9, 16, and 22: their incidence, likely origins, and mechanisms for cell lineage compartmentalization

Analysis of confined placental mosaicism (CPM) for trisomies 2, 3, 7, 8, 9, 16, and 22, in diagnostic chorionic villus sampling procedures, demonstrates apparent incidences of CPM for individual trisomies of between 9 and 91 cases per 100,000 pregnancies, with trisomy 7 being the most common. More detailed analysis of the percentage of aneuploid cells present, and the distribution of abnormality between the cytotrophoblast and extra-embryonic mesoderm cell lineages, shows a highly specific pattern for each chromosome. Theoretical considerations, in conjunction with direct observations, indicate that the overriding influence on the patterns of cell distribution seen in CPM is the distribution of aneuploid cells laid down during blastogenesis. This in turn reflects closely the origin of mosaicism from either correction of a trisomic conception or post-fertilization somatic error. The pattern of aneuploid cells for each trisomy, as seen at the end of the first trimester and later in pregnancy, can therefore be used to predict the relative contribution of meiotic and mitotic errors to CPM, and hence the likely incidences of uniparental disomy from this source, upd(16)mat being the most common (1 in 10,000 continuing pregnancies). In addition, CPM for trisomies 2, 3, and 8 shows strong evidence of a non-random distribution of aneuploid cells between the different extra-embryonic cell lineages. Analysis of comparable data from spontaneous abortion material repeats this non-random pattern for trisomies 2 and 3, and suggests that a similar phenomenon may also be occurring for trisomy 22. A non-random distribution could be attributable to selection for or against, or intolerance of, particular trisomic cells in certain lineages, but is more probably a result of either cell lineage-specific non-disjunction or consistent uneven compartmentalization of aneuploid cells during blastocyst development.