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Abstract In this case report, we describe a rare prenatal finding of a small marker chromosome. This marker chromosome corresponds to an inverted duplication of the 13q region 13q31.1q34 (or 13q31.1 → qter) with a neocentromere, detected during genetic analysis of a chorionic villus sample in a fetus with multiple congenital anomalies after a normal prenatal screening result by noninvasive prenatal testing.

In this case report, we describe a rare prenatal finding of a small marker chromosome. This marker chromosome corresponds to an inverted duplication of the 13q region 13q31.1q34 (or 13q31.1 → qter) with a neocentromere, detected during genetic analysis of a chorionic villus sample in a fetus with multiple congenital anomalies after a normal prenatal screening result by noninvasive prenatal testing. [ABSTRACT FROM AUTHOR]

We present a case of a fetus with cranial abnormalities typical of open spina bifida but with an intact spine shown on both ultrasound and fetal MRI. Expert ultrasound examination revealed a very small tract between the spine and the skin, and a postmortem examination confirmed the diagnosis of a dorsal dermal sinus. Genetic analysis found a mosaic 3q23q27 duplication in the form of a marker chromosome. This case emphasizes that meticulous prenatal ultrasound examination has the potential to diagnose even closed subtypes of neural tube defects. Furthermore, with cerebral anomalies suggesting a spina bifida, other imaging techniques together with genetic tests and measurement of alpha-fetoprotein in the amniotic fluid should be performed.

Background and objective A small supernumerary marker chromosome (sSMC) is a rare structurally abnormal chromosome in which no part can be identified by conventional cytogenetic banding technique. There is little known about the association of marker chromosomes with male infertility. We performed a molecular cyto-genetic characterization sSMCs and investigated their association with male infertility. Methods Among 4230 infertile male patients who underwent cytogenetic analyses from January 2008 to December 2018, the records of 15 patients who were diagnosed with sSMCs were reviewed. After ini-tial infertility evaluation, the patients received additional genetic tests including G-bands by trypsin using Giemsa (GTG-banding), Nucleolar organizer region (NOR) banding, Fluorescence in situ hybridization (FISH), and array comparative genomic hybridization (aCGH) analyses to further char-acterize and identify the origin of their marker chromosome. Testis biopsy was performed for the azoospermic patients to evaluate spermatogenic status. Results Among 15 infertile males with sSMCs, eight had nonobstructive azoospermia, five had severe oligozo-ospermia, and two had sperm concentrations above the lower normal limit. The marker chromosomes were identified as Y ring chromosomes (n = 8), an isodicentric Y chromosome (n = 1), a neocen-tromere Y chromosome (n = 1), a derivative chromosome 1 (n = 1), and an acrocentric short arms (n = 4). Conclusion Marker chromosomes appear to be a rare genetic cause of male infertility. Additional cytogenetic tests, including NOR banding, FISH, and aCGH, could help to characterize the origin of the marker chromosome. Appropriate genetic counseling for couples with infertility caused by a marker chromo-some should be recommended.

Abstract Background With only 11 patients reported, 5p tetrasomy belongs to rare postnatal findings. Most cases are due to small supernumerary marker chromosomes (sSMCs) or isochromosomes. The patients share common but unspecific symptoms such as developmental delay, seizures, ventriculomegaly, hypotonia, and fifth finger clinodactyly. Simple interstitial duplications leading to trisomies of parts of 5p are much more frequent and better described. Duplications encompassing 5p13.2 cause a defined syndrome with macrocephaly, distinct facial phenotype, heart defects, talipes equinovarus, feeding difficulties, respiratory distress and anomalies of the central nervous system, developmental delay and hypotonia. Case presentation We present a boy with dysmorphic features, developmental delay, intellectual disability and congenital anomalies, and a mosaic sSMC inv dup(5)(p15.33p15.1). He is the fourth and the oldest reported patient with distal 5p tetrasomy. His level of mosaicism was significantly different in lymphocytes (13.2%) and buccal cells (64.7%). The amplification in our patient is smaller than that in the three previously published patients but the only phenotype difference is the absence of seizures in our patient. Conclusions Our observations indicate that for the assessment of prognosis, especially with respect to intellectual functioning, the level of mosaicism could be more important than the extent of amplification and the number of extra copies. Evaluation of the phenotypical effect of rare chromosomal aberrations is challenging and each additional case is valuable for refinement of the genotype-phenotype correlation. Moreover, our patient demonstrates that if the phenotype is severe and if the level of sSMC mosaicism is low in lymphocytes, other tissues should be tested.

We report a rare case of a 14-month-old male child who was referred for developmental delay. Clinical examination revealed a hypotonic infant with speech delay and no dysmorphic features. The banding cytogenetics revealed a small supernumerary marker chromosome. Upon silver staining, the marker showed the presence of satellite regions on either ends. Further, analysis using fluorescence in situ hybridization on marker chromosome revealed its origin from chromosome 15. [ABSTRACT FROM AUTHOR]

Two autistic children with a chromosome 15q11-q13 inverted duplication are presented. Both had uneventful perinatal courses, normal electroencephalogram and magnetic resonance imaging scans, moderate motor delay, lethargy, severe hypotonia, and modest lactic acidosis. Both had muscle mitochondrial enzyme assays that showed a pronounced mitochondrial hyperproliferation and a partial respiratory chain block most parsimoniously placed at the level of complex III, suggesting candidate gene loci for autism within the critical region may affect pathways influencing mitochondrial function.

A 15-year-old boy was referred due to gynecomastia and short stature. He was overweight and showed the knuckle-dimple sign on the left hand, a short fourth toe on the left foot, and male external genitalia with a small phallus. His levels of estradiol and follicle-stimulating hormone were increased, and his testosterone concentration was normal. Other hormonal tests were within the normal range. Radiographs showed short fourth and fifth metacarpals and fourth metatarsal bones. The karyotype was reported as 46,X,+mar, and the marker chromosome was shown to originate from the Y chromosome, which was identified by fluorescence in situ hybridization. Polymerase chain reaction and direct sequencing were used to clarify the deleted loci of the Y chromosome by making use of Y-specific sequence-tagged sites (STSs). The sex-determining region Y and centromere were verified, and there were microdeletions on the long arm of the Y chromosome. The azoospermia factor (AZF) b region was partially deleted, and AZFa and AZFc were completely deleted. Two STS probes of sY143 and the Y chromosome RNA recognition motif in AZFb showed positive signals corresponding to Yq11.223. The karyotype of the patient was interpreted as 46,X,der(Y)del(Y)(q11.21q11.222)del(Y)(q11.23qter). Herein, we report a rare case of a boy presenting with gynecomastia and short stature with 46, X, +mar, which originated from the Y chromosome, which was identified to have Yq microdeletions.

Abstract Background Small supernumerary marker chromosomes can be derived from autosomes and sex chromosomes and can accompany chromosome pathologies, such as Turner syndrome. Case presentation Here, we present a case report of a patient with mosaic Turner syndrome and Dandy-Walker syndrome carrying a marker chromosome. We showed the presence of the marker chromosome in 33.8% of blood cells. FISH of the probe derived from the marker chromosome by microdissection revealed that it originated from the centromeric region of chromosome X. Additionally, we showed no telomeric sequences and no XIST sequence in the marker chromosome. This is the first report of these two syndromes accompanied by the presence of a marker chromosome. Conclusion Marker chromosome was X-derived and originated from centromeric region. Patient has mild symptoms but there is no XIST gene in marker chromosome. Trial registration CPG137 . Registered 03 March 2017.

In the process of generating presumably clonal human induced pluripotent stem cells (hiPSCs) from two carriers of a complex structural rearrangement, each having a psychotic disorder, we also serendipitously generated isogenic non-carrier control hiPSCs, finding that the rearrangement occurs as an extrachromosomal marker (mar) element. All confirmed carrier hiPSCs and differentiated neural progenitor cell lines were found to be mosaic. We caution that mar elements may be difficult to functionally evaluate in hiPSC cultures using currently available methods, as it is difficult to distinguish cells with and without mar elements in live mosaic cultures.

We report a case of a primary pulmonary mucosa‐associated lymphoid tissue (MALT) lymphoma with chromosomal aberration (49, XX, +3, +i(6)(p10), +mar). A 59‐year‐old woman was referred to our hospital for an abnormal chest shadow detected during a routine health check‐up in 2014. Chest computed tomography revealed a 3.2‐ × 2.3‐ × 2.0‐cm tumour shadow in the right middle lobe. Transbronchial biopsy did not result in the diagnosis of the tumour. Accordingly, as the tumour could have been malignant, right middle lobectomy was performed via video‐assisted thoracic surgery. On the basis of the results of immunohistochemical staining and gene analysis, the tumour was diagnosed as a primary pulmonary MALT lymphoma with chromosomal aberration (49, XX, +3, +i(6)(p10), +mar).

Background & Objective: Spontaneous pregnancy loss has always been the frustrating experience for the couples and concern clinician. Chromosomal abnormality in either of the parent is considered to be the one of the leading cause of recurrent spontaneous miscarriages. This study was designed to evaluate the possible chromosomal etiology of miscarriage and the subsequent intimacy of maternal or paternal genetic abnormality. Methods: This case-control study was conducted between January 2016 and October 2016 at a tertiary care hospital in Karachi. A total of thirty-two couples were selected who had suffered with recurrent spontaneous miscarriages (RSM). Using conventional cytogenetic technique karyotyping was performed on all of the subjects. For the control twenty couples were also selected with no history of pregnancy loss. All the karyotypes were recorded on the standard method. Data was analyzed through SPSS version 22. Results: Among thirty-two cases nine cases were found to have abnormal karyotype. In which sex chromosomal trisomy=02 (46,XY/47,XXY), marker chromosome=01 (47,XX,+mar), Robertsonian translocation=01 (45,XY,der,(14:21),(q10;q10)), reciprocal translocation=01 (46,XX,t(11;22)(q23;q11.2)), inversion=02 (46,XX,inv(9)(p11q13)) and minor structural abnormalities=02 (46,XX,15PS+) were found. Approximately equal ratio with 1:1.25 was observed among male and female carrier respectively. Nonsignificant difference was found between the ages of both carriers (p=0.34). Though a significant different value was calculated in the case of number of miscarriage (p=0.004*). Moreover, no significant association was found among spontaneous miscarriage (SM) and recurrent spontaneous miscarriage (RSM) with respect to maternal age (p= 0.157). Conclusion: In the recent study possible chromosomal abnormalities suggested the evaluation of the patient with the history of recurrent spontaneous miscarriage must include conventional cytogenetic. Moreover, probe development and extended investigation can ease the prognosis among pregnancy related complication. [ABSTRACT FROM AUTHOR]

The present study described the diagnosis of a fetus with sex chromosome mosaicism in three cell lines and two marker chromosomes. A 24-year-old woman underwent amniocentesis at 21 weeks and 4 days of gestation due to noninvasive prenatal testing identifying that the fetus had sex chromosome abnormalities. Amniotic cell culture revealed a karyotype of 45,X[13]/46,X,+mar1[6]/46,X,+mar2[9], and prenatal ultrasound was unremarkable. The woman underwent repeat amniocentesis at 23 weeks and 4 days of gestation for molecular detection. Single nucleotide polymorphism (SNP) microarray analysis on uncultured amniocytes revealed that the fetus had two Y chromosomes and 7.8-Mb deletions in Yq11.222q12. The deletion regions included DAZ, RBMY and PRY genes, which could cause spermatogenesis obstacle and sterility. Interphase fluorescence in situ hybridization (FISH) using centromeric probes DXZ1/DYZ3/D18Z1 was performed on uncultured amniocytes to verify the two marker chromosomes to be Y chromosome derivatives. According to these examinations, the mar1 was identified as a derivative of the Y chromosome with a deletion in Yq11.222q12, and the mar2 was identified as a dicentric derivative of the Y chromosome. The molecular karyotype was therefore 45,X,ish(DXZ1+, DYZ3-,D18Z1++)[5]/46,X,del(Y)(q11.222),ish(DXZ1+,DYZ3+,D18Z1++)[11]/46, X,idic(Y)(q11.222),ish(DXZ1+,DYZ3++,D18Z1++)[14]. The comprehensive use of cytogenetic, SNP array and FISH detections was advantageous for accurately identifying the karyotype, identifying the origin of the marker chromosome and preparing effective genetic counseling. [ABSTRACT FROM AUTHOR]

A Holstein-Fresian calf with multiple congenital malformations was subjected postmortem to anatomical and genetic investigation. The calf was small (20 kg), had shortened limbs and was unable to stand up. It lived only 44 days. Detailed anatomical investigation revealed the following features: head asymmetry, the relocation of the frontal sinus and eye orbits, hypoplastic thymus without neck part, ductus Botalli, unfinished obliteration in umbilical arteries, and a bilateral series of tooth germs in the temporal region. Cytogenetic examination, performed on in vitro cultured fibroblasts, showed a unique mosaic karyotype with a marker chromosome—60,XX[9 2%]/60,XX,+mar[8%], which was for the first time described in cattle. No other chromosome abnormalities indicating chromosome instabilities, like chromatid breaks or gaps were identified, thus teratogenic agent exposure during pregnancy was excluded. The marker chromosome (mar) was small and it was not possible to identify its origin, however, sequential DAPI/C (4’,6-diamidino-2-phenylindole) band staining revealed a large block of constitutive heterochromatin, which is characteristic for centromeric regions of bovine autosomes. We suppose that the identified marker chromosome was a result of somatic deletion in an autosome and its presence could be responsible for the observed developmental malformations. In spite of the topographic distance among the affected organs, we expected a relationship between anatomical abnormalities. To the of our best knowledge, this is the first case of a mosaic karyotype with a cell line carrying a small marker chromosome described in a malformed calf.

Abstract: Marker chromosomes are structurally abnormal chromosomes that may be supernumerary in karyotype or replace one of the chromosomes. Marker chromosomes very frequently can be a cause of different pathologies, including a intellectual disability. This study considers the molecular cytogenetic analysis of an acrocentric marker chromosome in a patient with autism and a intellectual disability. With the help of the painting probe localization of human chromosomes, its origin from the pericentromeric regions of the p and q arms of chromosome 15 is shown. For more detailed detection of the region of origin of this chromosome, its microdissection following localization on both healthy control and patient metaphase plates was carried out. Its origin from the nucleolus-containing chromosome 15 is confirmed. Because of the rDNA-containing plasmid localization, two of the ribosome RNA gene clusters were detected on the patient's chromosomes. Ag-NOR staining showed that both clusters are active. A possible contribution of the revealed chromosome pathology in clinical picture formation is discussed. [ABSTRACT FROM AUTHOR]

The prenatal finding of a small supernumerary marker chromosome (sSMC) is a challenge for genetic counseling. Our analytic algorithm is based on sSMC frequencies and multicolor FISH to accelerate the procedure. The chromosomal origin, size, and degree of mosaicism of the sSMC then determine the prognosis. We illustrate the effectiveness on 4 prenatally identified de novo mosaic sSMCs derived from chromosomes 13/21, X, 3, and 17. Three sSMC carriers had a good prognosis and apparently healthy children were born, showing no abnormality till the last examination at the age of 4 years. One case had a poor prognosis, and the parents decided to terminate the pregnancy. Our work contributes to the laboratory and clinical management of prenatally detected sSMCs. FISH is a reliable method for fast sSMC evaluation and prognosis assessment; it prevents unnecessary delays and uncertainty, allows informed decision making, and reduces unnecessary pregnancy terminations. [ABSTRACT FROM AUTHOR]

Abstract: Small supernumerary marker chromosomes (sSMC) are chromosomal fragments difficult to characterize genomically. Here, we detail a proband with schizoaffective disorder and a mother with bipolar disorder with psychotic features who present with a marker chromosome that segregates with disease. We explored the architecture of this marker and investigated its temporal origin. Array comparative genomic hybridization (aCGH) analysis revealed three duplications and three triplications that spanned the short arm of chromosome 9, suggestive of a chromoanasynthesis‐like event. Segregation of marker genotypes, phased using sSMC mosaicism in the mother, provided evidence that it was generated during a germline‐level event in the proband's maternal grandmother. Whole‐genome sequencing (WGS) was performed to resolve the structure and junctions of the chromosomal fragments, revealing further complexities. While structural variations have been previously associated with neuropsychiatric disorders and marker chromosomes, here we detail the precise architecture, human life‐cycle genesis, and propose a DNA replicative/repair mechanism underlying formation. [ABSTRACT FROM AUTHOR]

Background: Small supernumerary marker chromosomes can be derived from autosomes and sex chromosomes and can accompany chromosome pathologies, such as Turner syndrome. Case presentation: Here, we present a case report of a patient with mosaic Turner syndrome and Dandy-Walker syndrome carrying a marker chromosome. We showed the presence of the marker chromosome in 33.8% of blood cells. FISH of the probe derived from the marker chromosome by microdissection revealed that it originated from the centromeric region of chromosome X. Additionally, we showed no telomeric sequences and no XIST sequence in the marker chromosome. This is the first report of these two syndromes accompanied by the presence of a marker chromosome. Conclusion: Marker chromosome was X-derived and originated from centromeric region. Patient has mild symptoms but there is no XIST gene in marker chromosome. [ABSTRACT FROM AUTHOR]

Background: Marker chromosomes are small supernumerary chromosomes that cannot be unambiguously identified by chromosome banding techniques alone. However, the precise characterization of marker chromosomes is important for prenatal diagnosis and proper genetic counseling. In this study, we evaluated the chromosomal origin of marker chromosomes using a combination of banding cytogenetics and molecular cytogenetic techniques including diverse fluorescence in situ hybridization (FISH) assays and array comparative genomic hybridization (array CGH). Results: In a series of 2871 patients for whom cytogenetic analysis was requested, 14 cases with small supernumerary marker chromosomes (sSMCs) were identified. Nine sSMCs were mosaic, and five nonmosaic. Of the nine cases with known parental origins, four were identified as de novo, and four and one were maternally and paternally inherited, respectively. Six sSMCs were identified by FISH using centromeric probes; three sSMCs were derived from chromosome 15, including two heterochromatic sSMC(15)s and a large sSMC(15) spanning 15q11.1q13.1, and three sSMCs originated from chromosome 14 or 22. Array CGH revealed two cases with derivatives of chromosome 2 and whole chromosome painting multicolor-FISH (M-FISH) identified three cases with derivatives of chromosome 6, 16, and 19, respectively. One maker chromosome in Turner syndrome was characterized as sSMC(X) by preferential application of a centromeric probe for X-chromosome. In addition, one sSMC composed of genomic materials from chromosomes 12 and 18 was identified in parallel with parental karyotype analysis that revealed the reciprocal balanced translocation. Conclusions: This report is the largest study on sSMCs in Korea and expands the spectrum of sSMCs that are molecularly characterized. [ABSTRACT FROM AUTHOR]

Patients with Turner syndrome are generally characterized by having short stature with no secondary sexual characteristics. Some abnormalities, such as webbed neck, renal malformations (>50%) and cardiac defects (10%) are less common. The intelligence of these patients is considered normal. Non-mosaic monosomy X is observed in approximately 45% of postnatal patients with Turner syndrome and the rest of the patients have structural abnormalities or mosaicism involving 46,X,i(Xq), 45,X/46,XX, 45,X and other variants. The phenotype of 45,X/46,X,+mar individuals varies by the genetic continent and degree of the mosaicism. The gene content of the marker chromosome is the most important when correlating the phenotype with the genotype. Here we present an 11-year-old female who was referred for evaluation of her short stature and learning disabilities. Conventional cytogenetic investigation showed a mosaic 45,X/46,X,+mar karyotype. Fluorescencein situhybridization showed that the marker chromosome originated from the X chromosome within the androgen receptor (AR) and X-inactive specific transcript (XIST) genes. Therefore, it is possible that aberrant activation of the marker chromosome, compromising the AR and XIST genes, may modify the Turner syndrome phenotype. [ABSTRACT FROM PUBLISHER]

The presence of marker chromosomes in the human karyotype always requires a special diagnostic approach. Determination of the marker chromosome type and structure is of great diagnostic and prognostic importance. There are several methods of marker chromosomes identification, which differ in their informative value. The paper presents the results of cytogenetic and FISH diagnostics of supernumerical marker chromosomes (SMC) in patients' karyotype. Aim. To analyze the results of the cytogenetic and molecular cytogenetic diagnostics for patients with marker chromosomes, and to evaluate and compare the efficiency of the methods used. Methods. Karyotyping was done according to the standard methods. GTG, CBG, QFQ and NOR-Ag methods of differential staining were used. FISH was performed according to the manufacturer's instructions for CEP, LSI and WCP DNA-probes. Results. Marker chromosome was found in 15 of 7989 patients. Application of standard staining methods was effective in 66.6 % of cases. Combination of differential staining and FISH allowed identifying a marker chromosome in 83.3 %. 90 % of all marker chromosomes were identified as isochromosomes and 60 % of them were derivative from chromosome 15. Conclusions. The use of WCP probes is a main step in the marker chromosome identification with further application of CEP/LSI probes. If a marker chromosome has nonspecific DNA sequences more sensitive methods should be used. [ABSTRACT FROM AUTHOR]