Partial Trisomy 2p Research Articles

Large Chromosome 2p Duplication-Associated Mechanisms and Clinical Presentations

Chromosome 2p (chr2p) duplication, also known as trisomy 2p, is a rare chromosome abnormality associated with developmental delay, intellectual disability, behavioral problems, and distinctive facial features. Most of the reported cases involving trisomy 2p include additional copy number variants (CNVs) in other regions of the genome and are usually small in size. Little is known about the clinical outcomes of large duplications of chr2p as the sole cytogenetic abnormality. In this study, 193 samples at the Greenwood Genetic Center (GGC) with CNVs involving chr2p were evaluated, out of which 86 had chr2p duplications. Among them, 8 patients were identified with large chr2p duplications ranging in size from 9.3 Mb to 89 Mb, and no deletions or duplications involving other chromosomes were identified in those patients. These duplications were associated with inverted duplication, tandem duplication, and duplication as the result of translocation, with no additional CNVs identified by microarray analysis. Confirmation by conventional cytogenetics was performed in 7 of the 8 patients, and the translocations were confirmed by fluorescence in situ hybridization. Interestingly, 1 patient was found to have mosaic complete trisomy 2p as the result of an unbalanced de novo (X;2) chromosomal translocation. X-inactivation was skewed toward the derivative X chromosome, yet it did not appear to extend into the chromosome 2 material. Various shared clinical manifestations were observed in the individuals in this study, including developmental delay, hemifacial hypoplasia, cleft palate, and short stature, and they also have distinct features such as hypotonia, cerebellar hypogenesis, and corpus callosum agenesis, which might result from a gene dosage effect of the duplication. In conclusion, single-event large chr2p duplications can result from different mechanisms, including inverted or tandem duplications within chromosome 2, or translocations involving chromosome 2 and other chromosomes. Partial or complete trisomy 2p is commonly associated with developmental delay, and additional clinical features may be related to gene dosage effects.

Partial trisomy 9p and partial monosomy 7p of an infant inherited from maternal balanced translocation: a case report

BackgroundSubchromosomal deletions and duplications are the leading cause of congenital malformations and mental retardation in children. With the recent clinical application of genomic microarrays in the evaluation of patients with developmental delays and congenital malformations, it has led to the discovery of several new microdeletion and microduplication syndromes. However, there are no published reports involving patients with both microduplications in the 9p21.1-p24.3 region and microdeletions in the 7p22.1-p22.3 region.Case presentationWe report an infant with an autosomal abnormality confirmed by conventional karyotype combined with copy number variations sequencing (CNV-seq), showing the patient with an unbalanced translocation. The karyotype of the patient was 46, XX, der (7)t (7;9) (p22; p21) and CNV-seq results showed an approximately 32.34-Mb duplication in 9p21.1-p24.3 (200000-32540000) and an approximately 3.3-Mb deletion in 7p22.2-p22.3 (40000-3340000).ConclusionsThe patient carried an unbalanced translocation 46, XX, der (7)t (7;9) (p22; p21) derived from her mother. The clinical presentation is closely related to the size and position of the missing and duplicated chromosomes. To our knowledge, the simultaneous occurrence of de novo partial trisomy 9p(9p21.1-p24.3) and partial monosomy 7p (7p22.2-p22.3) has not previously been reported up until now. The present study additionally demonstrated that CNV-seq combined with karyotype is able to reliably detect unbalanced submicroscopic chromosomal aberrations.

Molecular cytogenetic characterization of a de novo derivative chromosome X with an unbalanced t(X;9) translocation in a fetus and literature review

Partial trisomy 9p is one of the most frequent autosome anomalies in newborn infants featured by craniofacial dysmorphism, intellectual disability and psychomotor growth. Female patients carrying monosomy Xq usually show mild symptoms due to skewed X-chromosome inactivation (XCI). Unbalanced translocation between chromosome X and chromosome 9 is rare in prenatal diagnosis. The skewed inactivation of abnormal X would spread into the extra segment of chromosome 9 presented in the der(X) leading to mild phenotypes. We reported on a fetus with high risk of trisomy 9p(13.32 Mb 9p23-p24.3 duplication)suggested by noninvasive prenatal testing (NIPT), the fetus was normal by ultrasonography. G-banding with trypsin-giemsa (GTG), copy number variations sequencing (CNV-seq) and fluorescence in situ hybridization (FISH) were carried out to delineate the nature of rearrangement. Final karyotype of the fetus was identified as 46,X,der(X)t(X;9)(q27;p23)dn. An unbalanced X-autosome translocation with a deletion of Xqter-q27.2 and a duplication of 9pter-p23 led to mild phenotypes with no obvious alteration by prenatal ultrasonography, or obvious pathological alterations after pregnancy termination.

17. Chromosome 2p duplication associated mechanisms and clinical presentations

Chromosome 2p duplication, also known as trisomy 2p, is a rare chromosome abnormality, which is associated with developmental delay, intellectual disability, behavioral problems, and distinctive facial features. Most of the reported cases involving trisomy 2p include additional copy number variants in other regions of the genome and are usually small in size. Little is known about the clinical outcomes of large duplications of chromosome 2p alone. In this study, we analyzed 8 patients with large chromosome 2p duplications ranging in size from 9.3 Mb to 89 Mb. These duplications were identified in association with inverted duplication, tandem duplication, and duplication as the result of translocation, with no other copy number variant identified by microarray analysis. Seven out of 8 patients had confirmation by conventional cytogenetics and all of the translocations were confirmed by FISH. Interestingly, one case is a patient with mosaic complete trisomy 2p, who has a de novo (X;2) chromosomal translocation. X-inactivation was shown for the derivative X chromosome, yet it does not appear to extend into the chromosome 2 material. While patients share common clinical manifestations including developmental delay, hemifacial hypoplasia, cleft palate, and short stature, they also have distinct features such as hypotonia, cerebellar agenesis/hypogenesis, and corpus callosum agenesis, which might result from a gene dosage effect of the duplication. Triplosensitivity has been reported in patients with duplications covering 2p24.3 region. Global developmental delay and autism have also been reported in patients with de novo microduplications of 2p15p16.1. In conclusion, large chromosome 2p duplications could result from inverted or tandem duplications within chromosome 2, or translocations involving chromosome 2 and other chromosomes. Partial or complete trisomy 2p are commonly associated with developmental delay, and additional clinical features may be related to gene dosage effect.

Prenatal diagnosis of the Dandy–Walker malformation associated with partial trisomy 12p and distal 15q deletion

Dandy-Walker malformation (DWM) is characterized by complete or partial agenesis of the cerebellar vermis, cyatic dilatation of the forth ventricle, and enlarged posterior fossa. However, the mechanism is still not completely understood up to now. In this study, we reported a rare case that a foetus with DWM showed partial trisomy 12p and distal 15q deletion. Karyotype analysis and chromosomal microarray analysis (CMA) were not always concordant with each other, and it is suggested that they should be performed for prenatal genetic diagnosis together. DWM is a rare central nervous system malformation, reported in 1/25-30,000 live births, characterized by complete or partial agenesis of the cerebellar vermis, cyatic dilatation of the forth ventricle, and enlarged posterior fossa (Kumar et al. 2001; Klein et al. 2003; Agrawal et al. 2016). The neurological development of children with DWM may range from normal to severely retarded, and cause variable clinical feature. Although several efforts have been made to explore its pathogenesis, however, it is still not completely understood. During the past decade, some genetic loci, microdeletion or duplication have been reported to be associated with DWM, such as 9p trisomy, partial deletions of the long arm of chromosome 13, genes ZIC1 and ZIC4 (von Kaisenberg et al. 2000; McCormack et al. 2003; Grinberg et al. 2004). In the present study, we describe a prenatal diagnosis case that a foetus with DWM on ultrasound scanning accepted genetic testing, and it revealed a microduplication of 12p13.33p11.1 and microdeletion of 15q11.2 in 750K single nucleotide polymorphism (SNP) array, while it showed 46,XX,der(8)(8pter→8q24::12p10→12qter),i(12)(p10) in karyotyping.

Fetal Cystic Hygroma Associated with Terminal 2p25.1 Duplication and Terminal 3p25.3 Deletion: Cytogenetic, Fluorescent in Situ Hybridization and Microarray Familial Characterization of Two Different Chromosomal Structural Rearrangements.

We report a prenatally diagnosed case of partial trisomy 2p and partial monosomy 3p, resulting from unbalanced translocation (2;3)(p25.1;p25.3) of paternal origin. Parents were non consanguineous Caucasians, with familial history of recurrent miscarriages on the father’s side. Detailed sonographic examination of the fetus showed a septated cystic hygroma measuring 6 mm at 13 weeks’ gestation. Karyotyping and fluorescent in situ hybridization (FISH) analysis of cultured amniotic fluid cells revealed an unbalanced translocation der(3)t(2;3)(p25.1; p25.3) and apparently balanced inv(3)(p13p25.3) in a fetus. Parental cytogenetic evaluation using karyotyping and FISH analysis showed the presence of both a balanced translocation and a paracentric inversion in father t(2;3) (p25.1;p25.3) inv(3)(p13p25.3). Microarray analysis showed a 11.6 Mb deletion at 3p26.3-p25.3 and duplication of 10.5 Mb at the 2p25.3-p25 region. The duplicated region at 2p25.1p25.3 contains 45 different genes, where 12 are reported as OMIM morbid genes with different phenotypical implications. The deleted region at 3p26.3-p25.3 contains 65 genes, out of which 27 are OMIM genes.Three of these (CNTN4, SETD5 and VHL) were curated by Clingene Dosage Gene Map and were given a high haplo-insufficiency score. Genes affected by the unbalanced translocation could have contributed to some specific phenotypic changes of the fetus in late pregnancy. The application of different cytogenetic methods was essential in our case, allowing the detection of different types of structural chromosomal aberrations and more thorough genetic counseling for future pregnancies.

A case of partial trisomy 2p with cleft palate treated by palatoplasty

A case of partial trisomy 2p with cleft palate treated by palatoplasty

Prenatal diagnosis of maternal partial trisomy 9p23p24.3 and 14q11.2q21.3 in a fetus: a case report

ObjectiveThis study aimed to report a fetus with maternal partial trisomy 9p and 14q and the phenotype detected in ultrasound.MethodsThe chromosome rearrangements in the fetus were characterized by G-banding and chromosome microarray analysis based on single nucleotide polymorphism (SNP) array of cultured amniocytes and compared with the parents’ karyotypes.ResultsThe fetal abnormal karyotype was 47,XY,+der(14)(9;14)(p23;q22). The SNP array revealed a duplicate 11.8-Mb 9p23-p24.3 fragment and a duplicate 29.6-Mb 14q11.2-q21.3 fragment. The peripheral blood karyotype of the mother was 46,XX,t(9;14)(p23;q22), while the father’s was normal at the level of 300~400 bands. A high-resolution karyotype analysis conformed the same abnormality of the mother at the level of 550~650 bands. These results indicated that the fetal chromosomal abnormality probably derived from the mother. The fetal nuchal translucency thickness was 3.5 mm, and the fetal heart was detected with around 1.0-mm ventricular defect by the ultrasound examination at 12-week gestation. The couple decided to terminate the pregnancy. They opted for in vitro fertilization and embryo transfer for the fourth pregnancy, which was successful.ConclusionsThe SNP array combined with cytogenetic analysis was particularly effective in identifying abnormal chromosomal rearrangements. These methods combined with the existing database information and fetal ultrasonography might provide a comprehensive and efficient way for the prenatal assessment of fetal situations. Preimplantation genetic diagnosis might effectively assist those women with an adverse pregnancy history in their next pregnancy.

A Case of Dental Treatment in a Patient with Partial Trisomy 7p Syndrome

A Case of Dental Treatment in a Patient with Partial Trisomy 7p Syndrome

Chromosomal Heterogeneity of the G-401 Rhabdoid Tumor Cell Line: Unusual Partial 7p Trisomy.

Rhabdoid tumor is a very aggressive and hardly curable pediatric malignancy. It commonly starts in the kidneys but also can occur in the brain, liver, and other organs. The treatment of this tumor usually involves a combination of surgery, radiation, and chemotherapy. Because this tumor is rare, there is still limited experience with a defined standard of care. Cytogenetic analysis is an important routine method to monitor chromosomal aberrations. We have analyzed metaphases of the G-401 rhabdoid tumor cell line. In these cells we have observed metaphases with derivative chromosome 12 arising from partial trisomy 7p. With increasing passage number the numbers of metaphases having this derivative chromosome 12 were found to be higher. In passage number 2 only one metaphase had this pathological chromosome 12. By passage number 10 and passage number 15 about 25 and 95% of this derivative chromosome 12 were found, respectively. We were able to subclone G-401 cells by limiting dilutions and successfully separated cells having apparently normal karyotypes from cells having derivative chromosome 12. Using the cell proliferation assay we showed that clones possessing the derivative chromosome 12 grew more rapidly than clones with normal chromosomes. The cell cycle analysis confirmed this observation. Overall, in this study we describe for the first time a 7p triplication in a rare rhabdoid tumor of kidney. Both types of clones described in this study could be used as a preclinical model to study the involvement of partial chromosome 7 alterations in the development of rhabdoid tumors.

OR38 Unusual HLA a locus resolution for a patient with partial trisomy 6p syndrome

OR38 Unusual HLA a locus resolution for a patient with partial trisomy 6p syndrome

Genotype/Phenotype correlation with partial duplications of 6p and 6q

Partial trisomy 6p and 6q are rare and clinical features include craniofacial changes, mental retardation and developmental delay. The study aims to correlate the genotype/ phenotype of a 6p and 6q duplication carrier. MVSN, female, single daughter of nonconsanguineous and healthy young couple. From an earlier relationship, the father had a 13-year-old son. Delivered by C-section, gestation of 37 weeks. The clinical analysis revealed: microcephaly, brachycephaly, syndromic facies, prominent forehead, hyperarousalism, strabismus, short nose, anteverted nares, smooth philtrum, thin lip, upper lip tented, micrognathism, dental anomalies, low-set ears, slender fingers, nails malformation, digitiform thumb, bilateral flat foot, hypotonia and neuropsychomotor developmental delay (NPMD). In the physical examination performed at 2 years of age, weight was 7,570 Kg (<3,58%), length was 74 cm (<3,95%) and cephalic perimeter was 43 cm (<2%). Classic cytogenetic techniques were performed (GTG banding and high resolution GTG), molecular cytogenetic (FISH) and cytogenetic (aCGH). The karyotype showed a mosaicism 47, XX, + mar [9]/46, XX [11] (ISCN, 2016). The parental karyotype was normal. The chromosomal changes found by aCGH indicate a genetic gain at chromosomal regions 6p11.2?q12 and 6q14.1?q14.3 with a size of 10.335 Mb and 10. 765 Mb, respectively. The patient presented mosaicism of a marker chromosome (sSMC) identified by the technique of FISH as coming from chromosome 6. In region 6p11.2?q12 the genes present are: PRIM2, GUSBP4, MTRNR2L9, KHDRBS2, LGSN, PTP4A1, PHF3, EYS and MCART3P. Heart defects and kidney problems were cited in the literature as being characteristic of trisomy 6p. However, patient did not present any of these phenotypic changes. The region 6q14.1?q14.3 contains more than 20 genes. The clinical signs found in patient such as: developmental delay, mental retardation, forehead prominent, short nose and thin lips has been described in other studies in the literature as characteristic of 6q trisomy. The presence of mosaicism excludes the possibility of sSMC as the sole responsible for the patient's phenotype. Our study correlates the phenotypic characteristics presented by the patient with partial trisomy 6q collaborating for family genetic counseling.

Familial Translocation t(5;15)(p14.2;q26.2) Causing a Mirror Combination of Several Known Genetic Conditions

AbstractTwo siblings with an unbalanced cytogenetic composition are described: a brother with partial trisomy 5p and distal 15q microdeletion, and a sister with partial monosomy 5p and distal 15q microduplication, resulting from a familial balanced translocation 46,XY; t(5;15)(p14.2;q26.2). To our best knowledge, there are no previous clinical and cytogenetic reports in the literature describing a family with concomitant presence of such a unique mirror combination. Clinical features of pure imbalances and the effects of their combination are discussed.

Clinical and molecular genetic characterization of two siblings with trisomy 2p24.3-pter and monosomy 5p14.3-pter.

Partial trisomy 2p syndrome is occasionally associated with neural tube defects (NTDs), such as anencephaly, encephalocele, and spina bifida, in addition to common features of intellectual disability, developmental delay, and characteristic facial appearance. The 2p24 region has been reported to be associated with NTDs. Here, we report the cases of 2 siblings with trisomy 2p24.3-pter and monosomy 5p14.3-pter caused by the paternal translocation t(2;5)(p24.3;p14.3). Of the two siblings, the elder sister had spina bifida. We determined the nucleotide sequences of the chromosomal breakpoints and found that the sizes of trisomy 2p and monosomy 5p segments were 18.77 and 17.89 Mb, respectively. NTDs were present in four of seven previously reported patients with trisomy 2p and monosomy 5p as well as in one of the two patients examined in the present study. Although the monosomy 5p of the nine patients were similar in size, the two patients reported here had the smallest size of trisomy 2p. When the clinical features of the nine patients were compared to the present two patients, the elder sister had postaxial polydactyly of the left foot in addition to the characteristic facial appearance and spina bifida, indicating that these features were associated with trisomy 2p24.3-pter. To our knowledge, this is the first study on spina bifida to determine the nucleotide sequences of breakpoints for trisomy 2p24.3-pter and monosomy 5p14.3-pter. Increased gene dosages of dosage-sensitive genes or genes at the trisomy segment (2p24.3) of the presented patients could be associated with NTDs of patients with trisomy 2p.

Prenatal diagnosis of partial monosomy 5p (5p15.1→pter) and partial trisomy 7p (7p15.2→pter) associated with cystic hygroma, abnormal skull development, and ventriculomegaly

ObjectivePrenatal diagnosis of concomitant chromosome 5p deletion syndrome and chromosome 7p duplication syndrome in a fetus with abnormal prenatal ultrasound is presented. Case ReportA 34-year-old woman was referred for amniocentesis at 22 weeks of gestation because of an irregular-shaped skull, bilateral ventriculomegaly, and nuchal cystic hygroma. Amniocentesis revealed a derivative chromosome 5 with a distal 5p deletion and an addendum of an extra unknown chromosomal segment at the breakpoint of 5p. Cytogenetic analysis of parental bloods revealed a karyotype of 46, XX, t(5;7)(p15.1;p15.2) in the mother and a karyotype of 46,XY in the father. The karyotype of the fetus was 46, XX, der(5) t(5;7)(p15.1;p15.2)mat consistent with partial monosomy 5p (5p15.1→pter) and partial trisomy 7p (7p15.2→pter). A malformed fetus was subsequently delivered with an irregular-shaped skull, a large anterior fontanelle, brachycephaly, hypertelorism, a high and prominent forehead, a large nuchal cystic hygroma, large low-set ears, a short and flattened nose, and micrognathia. Array comparative genomic hybridization analysis of the placenta revealed the result of arr 5p15.33p15.1 (22,179-18,133,327)×1.0, 7p22.3p15.2 (54,215-25,551,540)×3.0, indicating an 18.11-Mb deletion of 5p (5p15.33-p15.1) and a 22.5-Mb duplication of 7p (7p22.3-p15.2). Cord blood sampling revealed a karyotype of 46, XX, der(5)t(5;7) (p15.1;p15.2)mat. ConclusionFetuses with 5p deletion syndrome and 7p duplication syndrome may present ventriculomegaly, abnormal skull development, and cystic hygroma on prenatal ultrasound.

Prenatal diagnosis of a case with combined Wolf-Hirschhorn syndrome and Jacobsen syndrome

To detect chromosomal imbalance in a fetus with complex congenital heart disease, and to correlate the genotype with the phenotype. Routine G-banding was carried out to analyze the karyotypes of the fetus and its parents, and single nucleotide polymorphisms array (SNP-array) was used for delineating fine genomic aberrations. The detected aberrations were confirmed with multiplex ligation-dependent probe amplification (MLPA). The fetus and its parents all showed a normal karyotype, while array-SNP has detected a 13.87 Mb duplication at 4p16.3-p15.33 and a 15.65 Mb deletion at 11q23.3-q25 in the fetus. The results were confirmed by the MLPA assay. The partial trisomy 4p (Wolf-Hirschhorn syndrome) and partial monosomy 11q (Jacobsen syndrome) probably underlie the complex heart defects detected in the fetus. Analysis of the karyotypes of its parents offered no help for the determination of the aberrant type and recurrent risk. Compared with routine karyotype analysis, aberrant regions can be identified with array-SNP with greater resolution and accuracy. This has provided useful information for prenatal diagnosis and genetic counseling.

Clinical features of a case with trisomy 10q and monosomy 3p resulting from a maternal balanced translocation

Here we describe clinical and cytogenetic data on 2-year-old female child with partial trisomy for the distal part of the long arm of chromosome 10 (10q22–>qter) and a concomitant monosomy 3(p25–>pter) as a result of a maternal balanced reciprocal translocation. Her karyotype was ascertained as 46,XX,der(3)t(3;10)(p25;q22). The father had normal karyotype. The mother had an apparently balanced translocation involving chromosome 3 and 10 [46,XX,t(3;10)(p25;q22)]. This is the second reported case of partial trisomy 10q and partial trisomy 3p. Clinical features of this case and a few published cases will be reviewed briefly.

Large Cryptic Derivative Chromosome 8 Detected by SNP Chromosomal Microarray

Large Cryptic Derivative Chromosome 8 Detected by SNP Chromosomal Microarray

Streamlining NGS Workflows Using Cancer Samples by the Application of Tthe DNA Integrity Number (DIN) from the Genomic DNA Screentape Assay

Streamlining NGS Workflows Using Cancer Samples by the Application of Tthe DNA Integrity Number (DIN) from the Genomic DNA Screentape Assay

4p16.1-p15.31 duplication and 4p terminal deletion in a 3-years old Chinese girl: Array-CGH, genotype-phenotype and neurological characterization

Microscopically chromosome rearrangements of the short arm of chromosome 4 include the two known clinical entities: partial trisomy 4p and deletions of the Wolf-Hirschhorn critical regions 1 and 2 (WHSCR-1 and WHSCR-2, respectively), which cause cranio-facial anomalies, congenital malformations and developmental delay/intellectual disability. We report on clinical findings detected in a Chinese patient with a de novo 4p16.1-p15.32 duplication in association with a subtle 4p terminal deletion of 6Mb in size. This unusual chromosome imbalance resulted in WHS classical phenotype, while clinical manifestations of 4p trisomy were practically absent. This observation suggests the hypothesis that haploinsufficiency of sensitive dosage genes with regulatory function placed in WHS critical region, is more pathogenic than concomitant 4p duplicated segment. Additionally clinical findings in our patient confirm a variable penetrance of major malformations and neurological features in Chinese children despite of WHS critical region's deletion.