Complex cardiac malformation in a case of trisomy 9

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.

Structural evidence of injury or malformation in the brains of children with congenital heart disease

Neurological and developmental deficits are common in children with congenital heart disease (CHD). These are due to multiple factors that include the etiology of the CHD, the effects of abnormal cardiovascular function, and the possible sequelae of open heart surgery. CHD is frequently part of a multiple malformation syndrome that includes the brain. The causes of these syndromes include known or putative genetic defects. Abnormal cardiovascular function may be associated with poor brain growth, embolic infarction, cerebrovascular thrombosis, and abscess formation. Perioperative neurological complications include diffuse hypoxic-ischemic injury (particularly in neonates who undergo more than 45 to 60 minutes of hypothermic circulatory arrest), cerebral macro- and micro-emboli, dural sinus thrombosis, and cerebral hemorrhage. Neuroimaging, especially magnetic resonance imaging, is a useful prognostic instrument, can easily display gross congenital and acquired lesions, and should be performed preoperatively in addition to genetic studies. In some instances poor brain function may not be predicted unless slow head growth or microcephaly is present and thorough preoperative neurodevelopmental evaluation is encouraged.

Mosaic vs. nonmosaic trisomy 9: report of a liveborn infant evaluated by fluorescence in situ hybridization and review of the literature

We report on a newborn infant with multiple congenital anomalies and apparent nonmosaic trisomy 9 in the blood (by conventional cytogenetic studies) who died shortly after birth. Clinical observations at birth and autopsy are compared with phenotypes of mosaic and nonmosaic trisomy 9 cases reported previously. Unlike the initial cytogenetic analysis, fluorescence in situ hybridization (FISH) studies of metaphase and interphase blood cells and skin fibroblasts detected the presence of euploid and trisomy 9 cells. These results suggest that earlier reports of trisomy 9, which relied on conventional chromosome analysis of a few metaphase cells and/or only one tissue type, may not have excluded mosaicism, and that trisomy 9 may be viable only in the mosaic state.

Trisomy 9 syndrome: report of a case with Crohn disease and review of the literature

We report on a 6-year-old boy with mosaic trisomy 9. The patient was born at 42 weeks of gestation to a 27-year-old G1 white woman. Birth weight was 2,820 g, length 52 cm, and Apgar scores were 4 and 6 at 1 and 5 min, respectively. The infant presented with apparently low-set ears, overfolded helices, epicanthal folds, prominent nasal bridge, high-arched palate, micrognathia, bilateral dislocated hips, left genu recurvatum, and cryptorchidism. Chromosome analysis showed an unusual karyotype: 47,XY,+inv(9qh+)/47,XY,+mar. The marker chromosome was thought to be a remnant of the inv(9qh+) chromosome. The mother's karyotype was 46,XX,inv(9qh+), while the father's was 46,XY. At age 5 months, the patient developed seizures and gastroesophageal reflux. Crohn disease was diagnosed at age 2 years, although symptoms began at age 1 year. Recurrent bouts of pneumonia have occurred since the patient's birth. Severe psychomotor retardation was also noted. Trisomy 9 syndrome was first reported in 1973. Over 30 cases have been reported since then. Of these cases reports, only 5 patients were older than 1 year. Inflammatory bowel disease has been reported in association with other chromosome abnormalities, but to our knowledge, has not been reported in trisomy 9 syndrome.

Trisomy 9: review and report of two new cases

Trisomy 9 is a relatively uncommon chromosome abnormality that may sometimes be seen in the nonmosaic state. We reviewed 23 mosaic and 15 nonmosaic cases of trisomy 9, including 2 new cases, in order to better define the prognosis and phenotype of this disorder. A recognizable trisomy 9 phenotype was identified and included a "bulbous" nose, microphthalmia, and dislocated limbs. Other nonspecific anomalies involving various organ systems were also common. With one exception, all survivors had severe mental impairment. Mosaicism for trisomy 9 predicted longer survival, but the degree of mosaicism in lymphocytes or fibroblasts did not predict survival or degree of impairment. Parental chromosome variations were not uncommon. In contrast to prior reports, no specific prognostic finding was identified. A meiotic origin with loss of a trisomic cell line in mosaic cases is suggested.

Characteristics of structural heart defects in trisomy 9 and their relationship to those in trisomy 13, 18, and 21

The hearts from two live-born full-term infants with nonmosaic trisomy 9 (one complete trisomy 9, one partial trisomy 9) were studied after death. Both demonstrated conal and valvular anomalies associated with ventricular septal defects. These specific malformations are discussed in relation to published cases of trisomy 9 and the cardiac defects of other autosomal trisomies (13, 18, and 21).

Cardiac histologic pathology characteristic of trisomies 13 and 21

To identify fetal histologic features characteristic of specific chromosomal anomalies, we reviewed histologic slides of 415 cases, including therapeutic and spontaneous abortuses, stillbirths, and perinatal deaths. These included 126 cases (30%) with karyotypically confirmed trisomy 21 and 23 cases (5.5%) with trisomy 13. Two histologic abnormalities of the fetal heart were identified that correlated with specific karyotypic abnormalities: (1) a discrete central papillary muscle calcification was present in 14 of 85 (16%) cases with trisomy 21, in seven of 18 (39%) cases with trisomy 13, and in six of 255 (2%) controls (P less than .001); and (2) a focal ventricular epicardial lymphocytic infiltrate was present in 22 of 93 (24%) cases with trisomy 21 versus nine of 284 (3%) controls (P less than .001). When both histologic abnormalities coexisted, trisomy 21 was present in five of six cases (83%). Neither histologic finding was significantly associated with fetal or maternal infection or congenital heart defects. In a restricted prospective study of the hearts of fetuses with trisomy 21, papillary muscle calcification was demonstrated by specimen radiographs in four of six (67%) cases; one case was studied by specimen ultrasonogram, which identified a papillary muscle echodensity. We conclude that (1) a focal ventricular epicardial lymphocytic infiltrate is characteristic of trisomy 21, (2) papillary muscle microcalcifications are characteristic of trisomies 13 and 21, and (3) further studies are needed to determine whether papillary muscle calcification might be useful in antenatal ultrasonographic screening for chromosomal anomalies.

Atrioventricular canal associated with trisomy 9

The features of a newborn with the full clinical aspect of trisomy 9 presenting with an atrioventricular canal is described. This association of anomalies has never been reported before. Interestingly, the patient also had a left-sided obstruction which is known to be more characteristically associated with atrioventricular canal without Down's syndrome.

Prenatal detection of trisomy 9 mosaicism

Chromosomal mosaicism in amniotic fluid cells poses a serious dilemma in prenatal diagnosis since the observation may represent: (1) pseudomosaicism--an inconsequential tissue culture artefact; or (2) true mosaicism--occurring in approximately 0.20 per cent of amniocenteses with a significant impact on pregnancy outcome. Mosaicism for trisomy 9 was observed in an amniotic fluid specimen obtained for advanced maternal age with two cell lines [46,XX (46 per cent)/47,XX, +9 (54 per cent)] present in each of four culture flasks. Since more than 75 per cent of newborns with trisomy 9 mosaicism have complex cardiac malformations, a fetal echocardiogram was obtained at 20 weeks' gestation and interpreted as normal. A fetal blood sample (22 weeks' gestation) disclosed only a single trisomy 9 cell among the 100 metaphases analysed. However, a second fetal echocardiogram performed at the time of blood sampling suggested a non-specific cardiac anomaly. Fetal autopsy following elective pregnancy termination revealed several malformations including severe micrognathia, persistence of the left superior vena cava, and skeletal anomalies. Cytogenetic studies of cell cultures derived from several fetal tissues demonstrated trisomy 9 ranging from 12 to 24 per cent.

Further observations of ocular pathology in trisomy 9

The ocular pathology in a new patient with mosaic trisomy 9 comprised major anomalies and contrasted sharply with the findings in a previous case reported by us. The ocular changes in this case were, in essence, indistinguishable from those encountered in the most severe form of trisomy 13. Similarities to trisomy 18 and 21 were further evidence of the overlap of ocular findings in autosomal trisomies. There is increasing evidence that most, if not all, chromosomes have some role in regulating ocular embryogenesis.

Human chromosome-specific repetitive DNA sequences: novel markers for genetic analysis

Two recombinant DNA clones that are localized to single human chromosomes were isolated from a human repetitive DNA library. Clone pHuR 98, a variant satellite 3 sequence, specifically hybridizes to chromosome position 9qh. Clone pHuR 195, a variant satellite 2 sequence, specifically hybridizes to chromosome position 16qh. These locations were determined by fluorescent in situ hybridization to metaphase chromosomes, and confirmed by DNA hybridizations to human chromosomes sorted by flow cytometry. Pulsed field gel electrophoresis analysis indicated that both sequences exist in the genome as large DNA blocks. In situ hybridization to intact interphase nuclei showed a well-defined, localized organization for both DNA sequences. The ability to tag specific human autosomal chromosomes, both at metaphase and in interphase nuclei, allows novel molecular cytogenetic analyses in numerous basic research and clinical studies.

Coloboma and microphthalmos in chromosomal aberrations. Chromosomal aberrations and neural crest cell developmental field

A survey of more than 500 reports on patients with autosomal chromosomal aberrations associated with microphthalmos and/or coloboma shows that these anomalies are unspecific. Anterior chamber anomalies were common as were abnormal ears, preauricular pits and tags, cleft lip-palate, micrognathia, urogenital malformations, congenital heart disease, atresia of the anus and minor malformations of the hands and feet. It is proposed that the chromosomal aberrations induce faulty development of neural crest cells and rostral neural plate derivatives.

Genetic analysis of malformations causing perinatal mortality

An analysis of congenital malformations, other than neural tube defects, which have contributed to perinatal mortality in Leicestershire is presented for the years 1976 to 1982 inclusive. Chromosomal, single gene, or polygenic inheritance accounted for 67% of cases.