Case report: Detection of fetal trisomy 9 mosaicism by multiple genetic testing methods: Report of two cases

Chromosomal mosaicism remains a perpetual diagnostic and clinical dilemma. In the present study, we detected two prenatal trisomy 9 mosaic syndrome cases by using multiple genetic testing methods. The non-invasive prenatal testing (NIPT) results suggested trisomy 9 in two fetuses. Karyotype analysis of amniocytes showed a high level (42%–50%) of mosaicism, and chromosomal microarray analysis (CMA) of uncultured amniocytes showed no copy number variation (CNV) except for large fragment loss of heterozygosity. Ultrasound findings were unmarkable except for small for gestational age. In Case 1, further umbilical blood puncture confirmed 22.4% and 34% trisomy 9 mosaicism by CMA and fluorescent in situ hybridization (FISH) respectively. After comprehensive consideration of the genetic and ultrasound results, the two gravidas decided to receive elective termination and molecular investigations of multiple tissue samples from the aborted fetus and the placenta. The results confirmed the presence of true fetoplacental mosaicism with levels of trisomy 9 mosaicism from 76% to normal in various tissues. These two cases highlight the necessity of genetic counseling for gravidas whose NIPT results highly suggest the risk of chromosome 9 to ascertain the occurrence of mosaicism. In addition, the comprehensive use of multiple genetic techniques and biological samples is recommended for prenatal diagnosis to avoid false-negative results. It should also be noted that ultrasound results of organs with true trisomy 9 mosaicism can be free of structural abnormalities during pregnancy.

Pitfalls and management of corrective spinal surgery in trisomy 9 mosaicism: a report of three cases

PURPOSE

The aim of this case series is to present the outcomes of surgical correction of hyperkyphosis, and subsequent management of complications for three patients with a rare chromosomopathy, Trisomy 9 Mosaicism (T9M).

METHODS

Case series with 2 year outcomes following index surgery.

RESULTS

Case 1 presented at 9 years of age with 103° of kyphosis (T3-T10), which progressed to 118° despite bracing. Case 2 presented at 7 years of age with 113° of kyphosis (T3-T11). Case 3 presented at 4 years of age with 103° of kyphosis (T1-T11). Cases 1 and 2 underwent T2-L2 posterior instrumented spinal fusion (PISF). Upon follow up, radiographs for Cases 1 and 2 revealed severe, symptomatic proximal junctional kyphosis (PJK) of 71° and 50°, respectively, requiring surgical revision proximally to the C4 level. Case 3 underwent placement of magnetically controlled growing rods given young age and growth potential. Surgical levels for Case 3 were extended from C4-pelvis in an attempt to prevent development of symptomatic PJK. Most recent radiographs for Case 3 taken 21 months postoperatively demonstrate a stable 50° of kyphosis. PJK above C4 was noted but is stable and asymptomatic.

CONCLUSION

T9M often presents with progressive hyperkyphosis. Despite instrumentation above the upper end vertebra (UEV), PJK may be a common complication in this small patient population. This novel report on spine deformity correction in the T9M population may provide preliminary guidance for the treatment of hyperkyphosis in patients with T9M and help surgeons avoid common pitfalls.

LEVEL OF EVIDENCE

IV.

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.

Case report of a pseudo-isodicentric chromosome 9 resulting in mosaic trisomy 9

Due to the variable presentation of mosaic chromosomal abnormalities, cases such as this are needed to define the phenotypic spectrum. It also highlights the importance of chromosome analysis to identify structural abnormalities that result in aneuploidy.

A Case of Trisomy 9 Mosaicism Confirmed by Microarray Test

Trisomy 9 mosaicism syndrome is a rare chromosomal abnormality with a high incidence of natural abortion and perinatal death. This syndrome is characterized by intrauterine growth retardation, mental retardation, craniofacial dysmorphism including a prominent nasal bridge with a short root and a fish-shaped mouth with thin lips, skeletal abnormalities, congenital heart defects, and genital abnormalities. The incidence and severity of malformations depend on the percentage of trisomic cells in the different tissues. We report a neonate who had the characteristic features of trisomy 9 syndrome with dysmorphic features including micrognathia, microcephaly, a low-set and malformed ear, a prominent lip, and cardiac defect. No chromosomal abnormalities were detected on a routine peripheral blood chromosomal analysis; however, a chromosomal abnormality with trisomy 9 mosaicism (low-level mosaic type) was detected on genetic tests. This is thought to be due to the low proportion of trisomic cells, and for this reason, the patient in this case shows a better prognosis than four patients previously reported in Korea, they were all diagnosed by peripheral blood chromosome testing.

Ontogenetic and Pathogenetic Views on Somatic Chromosomal Mosaicism

Intercellular karyotypic variability has been a focus of genetic research for more than 50 years. It has been repeatedly shown that chromosome heterogeneity manifesting as chromosomal mosaicism is associated with a variety of human diseases. Due to the ability of changing dynamically throughout the ontogeny, chromosomal mosaicism may mediate genome/chromosome instability and intercellular diversity in health and disease in a bottleneck fashion. However, the ubiquity of negligibly small populations of cells with abnormal karyotypes results in difficulties of the interpretation and detection, which may be nonetheless solved by post-genomic cytogenomic technologies. In the post-genomic era, it has become possible to uncover molecular and cellular pathways to genome/chromosome instability (chromosomal mosaicism or heterogeneity) using advanced whole-genome scanning technologies and bioinformatic tools. Furthermore, the opportunities to determine the effect of chromosomal abnormalities on the cellular phenotype seem to be useful for uncovering the intrinsic consequences of chromosomal mosaicism. Accordingly, a post-genomic review of chromosomal mosaicism in the ontogenetic and pathogenetic contexts appears to be required. Here, we review chromosomal mosaicism in its widest sense and discuss further directions of cyto(post)genomic research dedicated to chromosomal heterogeneity.

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.

Cardiac Failure in a Trisomy 9 Patient Undergoing Anesthesia: A Case Report

A 27-year-old female with Trisomy 9 mosaicism presented to Children's Hospital Colorado for outpatient dental surgery under general anesthesia. The patient's past medical history was also significant for premature birth, gastroesophageal reflux, scoliosis and kyphosis, obesity, and developmental delay. Per her mother's report, the patient had no cardiac issues. She had undergone multiple previous general anesthetics, some of which documented respiratory complications such as laryngospasm, bronchospasm, and possible aspiration. During this anesthetic, the patient became hypotensive on induction, with sluggish response to intravenous fluids, glycopyrrolate, and ephedrine. Her electrocardiogram demonstrated what appeared to be left bundle branch block at baseline, with possible ST segment changes after induction. Due to her abnormal reaction to the induction and subsequent treatment for hypotension, an echocardiogram was performed. The patient was found to have an ejection fraction of 25%-30%. The anesthetic was uneventful for the remainder of the procedure, and following recovery, the patient was admitted by the heart failure team for further care.

Deletions and de novo mutations of SOX11 are associated with a neurodevelopmental disorder with features of Coffin-Siris syndrome

BACKGROUND

SOX11 is a transcription factor proposed to play a role in brain development. The relevance of SOX11 to human developmental disorders was suggested by a recent report of SOX11 mutations in two patients with Coffin-Siris syndrome. Here we further investigate the role of SOX11 variants in neurodevelopmental disorders.

METHODS

We used array based comparative genomic hybridisation and trio exome sequencing to identify children with intellectual disability who have deletions or de novo point mutations disrupting SOX11. The pathogenicity of the SOX11 mutations was assessed using an in vitro gene expression reporter system. Loss-of-function experiments were performed in xenopus by knockdown of Sox11 expression.

RESULTS

We identified seven individuals with chromosome 2p25 deletions involving SOX11. Trio exome sequencing identified three de novo SOX11 variants, two missense (p.K50N; p.P120H) and one nonsense (p.C29*). The biological consequences of the missense mutations were assessed using an in vitro gene expression system. These individuals had microcephaly, developmental delay and shared dysmorphic features compatible with mild Coffin-Siris syndrome. To further investigate the function of SOX11, we knocked down the orthologous gene in xenopus. Morphants had significant reduction in head size compared with controls. This suggests that SOX11 loss of function can be associated with microcephaly.

CONCLUSIONS

We thus propose that SOX11 deletion or mutation can present with a Coffin-Siris phenotype.