Atypical manifestations of two cases of trisomy 9 syndrome: Rethinking development delay

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.

Mosaic trisomy 9 presenting with congenital heart disease, facial dysmorphism and pigmentary skin lesions: intricate issues of genetic counseling

Chromosomal mosaicism for full aneuploidy involving chromosome 9 is an uncommon chromosomal abnormality. Mosaic trisomy 9 clinical manifestations are highly variable and difficult to predict. The authors present a case of mosaic trisomy 9 with typical clinical manifestations(facial dysmorphism, various internal organ malformations and severe psychomotor retardation), pigmentary mosaic skin lesions along the lines of Blaschko and evidence of maternal uniparental disomy in skin.

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.

Patient with trisomy 9p and a hypoplastic left heart with a tricentric chromosome 9

We present a patient with a hypoplastic left heart (HLH), dislocations of the hips and knees, and minor dysmorphic features, who had an abnormal karyotype that resulted in trisomy for 9p and a portion of 9q: 46,((, dic(or tri?)(9)(9pter --> 9q34::9q21 --> 9pter).ish(WCP9++).ish(D9Z5X4 +/+++). The derivative chromosome consisted of an additional copy of the proximal q arm and p arm attached to 9qter in an inverted fashion. Fluorescence in situ hybridization (FISH) using a chromosome 9 beta-satellite probe revealed three signals on the abnormal chromosome 9, suggesting the presence of 3 pericentromeric regions on the der(9). The 9q subtelomere was present on both the normal and derivative chromosome 9, suggesting that very little material, if any, is deleted.

Ring chromosome 8 syndrome: further characterization

We describe two de novo cases of extra r(8) confirmed by fluorescent in situ hybridization (FISH). Based on these two and eight additional cases of extra r(8) confirmed by FISH, the phenotype is better documented. One of our patients had minor facial anomalies, near-normal growth, and neurological development. She had a ring in each cell analyzed. The second had minor craniofacial anomalies and growth and mental retardation. He had a small or double-sized ring in each cell. The phenotype of these 10 cases ranges from almost normal in an adult with 10% mosaicism to variable degrees of minor anomalies, growth retardation, and mental retardation overlapping the mosaic +8 syndrome.