Showing papers on "Ring chromosome published in 2013"

De novo centromere formation on a chromosome fragment in maize

Abstract: The centromere is the part of the chromosome that organizes the kinetochore, which mediates chromosome movement during mitosis and meiosis. A small fragment from chromosome 3, named Duplication 3a (Dp3a), was described from UV-irradiated materials by Stadler and Roman in the 1940s [Stadler LJ, Roman H (1948) Genetics 33(3):273–303]. The genetic behavior of Dp3a is reminiscent of a ring chromosome, but fluoresecent in situ hybridization detected telomeres at both ends, suggesting a linear structure. This small chromosome has no detectable canonical centromeric sequences, but contains a site with protein features of functional centromeres such as CENH3, the centromere specific H3 histone variant, and CENP-C, a foundational kinetochore protein, suggesting the de novo formation of a centromere on the chromatin fragment. To examine the sequences associated with CENH3, chromatin immunoprecipitation was carried out with anti-CENH3 antibodies using material from young seedlings with and without the Dp3a chromosome. A novel peak was detected from the ChIP-Sequencing reads of the Dp3a sample. The peak spanned 350 kb within the long arm of chromosome 3 covering 22 genes. Collectively, these results define the behavior and molecular features of de novo centromere formation in the Dp3a chromosome, which may shed light on the initiation of new centromere sites during evolution.

Rapid assessment of high-dose radiation exposures through scoring of cell-fusion-induced premature chromosome condensation and ring chromosomes.

Abstract: Analysis of premature chromosome condensation (PCC) mediated by fusion of G0-lymphocytes with mitotic CHO cells in combination with rapid visualization and quantification of rings (PCC-Rf) is proposed as an alternative technique for dose assessment of radiation-exposed individuals. Isolated lymphocytes or whole blood from six individuals were γ-irradiated with 5, 10, 15 and 20Gy at a dose rate of 0.5Gy/min. Following either 8- or 24-h post-exposure incubation of irradiated samples at 37°C, chromosome spreads were prepared by standard PCC cytogenetic procedures. The protocol for PCC fusion proved to be effective at doses as high as 20Gy, enabling the analysis of ring chromosomes and excess PCC fragments. The ring frequencies remained constant during the 8-24-h repair time; the pooled dose relationship between ring frequency (Y) and dose (D) was linear: Y=(0.088±0.005)×D. During the repair time, excess fragments decreased from 0.91 to 0.59 chromatid pieces per Gy, revealing the importance of information about the exact time of exposure for dose assessment on the basis of fragments. Compared with other cytogenetic assays to estimate radiation dose, the PCC-Rf method has the following benefits: a 48-h culture time is not required, allowing a much faster assessment of dose in comparison with conventional scoring of dicentrics and rings in assays for chemically-induced premature chromosome condensation (PCC-Rch), and it allows the analysis of heavily irradiated lymphocytes that are delayed or never reach mitosis, thus avoiding the problem of saturation at high doses. In conclusion, the use of the PCC fusion assay in conjunction with scoring of rings in G0-lymphocytes offers a suitable alternative for fast dose estimation following accidental exposure to high radiation doses.

Human Ring Chromosomes - New Insights for their Clinical Significance.

Abstract: Twenty-nine as yet unreported ring chromosomes were characterized in detail by cytogenetic and molecular techniques For FISH (fluorescence in situ hybridization) previously published high resolution approaches such as multicolor banding (MCB), subcentromere-specific multi-color-FISH (cenM-FISH) and two to three-color-FISH applying locus-specific probes were used Overall, ring chromosome derived from chromosomes 4 (one case), 10 (one case), 13 (five cases), 14, (three cases), 18 (two cases), 21 (eight cases), 22 (three cases), X (five cases) and Y (one case) were studied Eight cases were detected prenatally, eight due developmental delay and dysmorphic signs, and nine in connection with infertility and/or Turner syndrome In general, this report together with data from the literature, supports the idea that ring chromosome patients fall into two groups: group one with (severe) clinical signs and symptoms due to the ring chromosome and group two with no obvious clinical problems apart from infertility

Ring chromosome 9 in a girl with developmental delay and dysmorphic features: case report and review of the literature.

Abstract: In this report, we describe a female child with dysmorphic features and developmental delay. Chromosome microarray analysis followed by conventional karyotyping revealed a ring chromosome 9 with a 12 Mb deletion at 9pter-p23 and a 540 kb deletion at 9q34.3-qter. Four percent of the analyzed cells had monosomy 9. The patient has the features of both the Kleefstra syndrome and the chromosome 9p-syndrome, including trigonocephaly, long philtrum, hypertelorism, and retro-/micronagthia. The deletion of the patient overlaps with several of the proposed critical regions for the 9p deletion syndrome.

Array-CGH characterization and genotype-phenotype analysis in a patient with a ring chromosome 6

Abstract: Background Ring chromosome 6 is a rare constitutional abnormality that generally occurs de novo. The related phenotype may be highly variable ranging from an almost normal phenotype to severe malformations and mental retardation. These features are mainly present when genetic material at the end of the chromosome is lost. The severity of the phenotype seems to be related to the size of the deletion. About 25 cases have been described to date, but the vast majority reports only conventional cytogenetic investigations.

Smallest critical region for microcephaly in a patient with mosaic ring chromosome 13.

Abstract: A ring chromosome 13 or r(13) exhibits breakage and reunion at breakage points on the long and short arms of chromosome 13, with deletions of the chromosomal segments distal to the breakage points. The r(13) chromosome accounts for approximately 20% of ring chromosomes compatible with life. We describe a female patient with mental retardation, growth retardation, microcephaly, craniofacial dysmorphy, hearing impairment, and prolonged prothrombin time. Chromosomal analysis via GTG banding of peripheral blood lymphocytes revealed a karyotype of 46,XX,r(13)(p13q34)[71]/45,XX,-13[12]/ 46,XX,dic r(13;13)(p13q34;p13q34)[9]/46,XX,-13,+mar[5]/47, XX,+r(13) (p13q34)x2[2]/46,XX[1] at the age of 6 years and 46,XX,r(13)(p13q34)[82]/45,XX,-13[14]/46,XX,dic r(13;13)(p13q34; p13q34)[2]/46,XX, -13,+mar[2]. Array comparative genomic hybridization analysis of the blood demonstrated a 4.37-Mb deletion on chromosome 13q [arr cgh 13q34q34(109,743,729-144,110,721)]. A cytogenetic study of peripheral blood revealed a rare chromosomal abnormality associated with different cell lines that included structural and numerical abnormalities of chromosome 13. This case, along with 14 previously reported cases, indicate that the smallest critical region for chromosome 13 microcephaly is 109,743,729-144,110,721.

Ring chromosome 10: report on two patients and review of the literature

Abstract: Ring chromosome 10—r(10)—is a rare disorder, with 14 cases reported in the literature, but only two with breakpoint determination by high-resolution techniques. We report here on two patients presenting a ring chromosome 10, studied by G-banding, fluorescent in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA) and SNP-array techniques, in order to investigate ring instability and determine breakpoints. Patient 1 showed a r(10)(p15.3q26.2) with a 7.9 Mb deletion in 10q26.2-q26.2, while patient 2 showed a r(10)(p15.3q26.13) with a 1.0 Mb deletion in 10p15.3 and a 8.8 Mb deletion in 10q26.13-q26.3, both unstable. While patient 1 presented with clinical features usually found in patients with r(10) and terminal 10q deletion, patient 2 presented characteristics so far not described in other patients with r(10), such as Dandy-Walker variant, osteopenia, semi-flexed legs, and dermal pigmentation regions. Our data and the data from literature show that there are no specific clinical findings to define a r(10) syndrome.

Clinical, cytogenetic and molecular characterization of two cases of mosaic ring chromosome 13

Abstract: The occurrence of mosaic ring chromosome 13 is rare. The mechanism of ring chromosome formation is usually associated with loss of genetic material. We report 2 cases of mosaic ring chromosome 13, resulting in deletion of 13qter. The first patient, a 15 year-old boy, presented a delayed psychomotor development, mental retardation, dysmorphic features and bleeding disorders associated with a de novo terminal 13q34 deletion. The second case was a foetus of 31 weeks with prenatal diagnosis of severe malformation such as holoprosencephaly, congenital cardiac defects, gastro-intestinal abnormalities with intrauterine growth retardation, the molecular analysis showed a de novo deletion encompassing the region 13q31.3-q34.

Molecular cytogenetic and phenotypic characterization of ring chromosome 13 in three unrelated patients.

Abstract: We report on the cytogenetic and molecular investigations of constitutional de-novo ring chromosome 13s in three unrelated patients for better understanding and delineation of the phenotypic variability characterizing this genomic rearrangement The patient’s karyotypes were as follows: 46,XY,r(13)(p11q34) dn for patients 1 and 2 and 46,XY,r(13)(p11q14) dn for patient 3, as a result of the deletion in the telomeric regions of chromosome 13 The patients were, therefore, monosomic for the segment 13q34 → 13qter; in addition, for patient 3, the deletion was larger, encompassing the segment 13q14 → 13qter Fluorescence in situ hybridization confirmed these rearrangement and array CGH technique showed the loss of at least 29 Mb on the short arm and 47 Mb on the long arm of the chromosome 13 in patient 2 Ring chromosome 13 (r(13)) is associated with several phenotypic features like intellectual disability, marked short stature, brain and heart defects, microcephaly and genital malformations in males, including undescended testes and hypospadias However, the hearing loss and speech delay that were found in our three patients have rarely been reported with ring chromosome 13 Although little is known about its etiology, there is interesting evidence for a genetic cause for the ring chromosome 13 We thus performed a genotype-phenotype correlation analysis to ascertain the contribution of ring chromosome 13 to the clinical features of our three cases

Gain of 11q by an additional ring chromosome 11 and trisomy 18 in CD5-positive intravascular large B-cell lymphoma.

Abstract: Chromosomal abnormalities of intravascular large B-cell lymphoma (IVLBCL), a rare form of extranodal diffuse large B-cell lymphoma, have been described in only a small number of cases. A 59-year-old female presented with pancytopenia and splenomegaly. Bone marrow was normocellular with 30.4% abnormal large lymphoid cells that were positive for CD5, CD19, CD20, HLA-DR and λ chain. Bone marrow biopsy showed intrasinusoidal infiltration of large lymphoid cells. G-banding and spectral karyotyping of the bone marrow cells demonstrated a complex karyotype as follows : 48,XX,-8,+r(11),+12,del(12)(p?) ×2,+18,der(19)(19?::p13 → qter),der(21)t(8;21)(q11.2;p11.2). Fluorescence in situ hybridization on interphase nuclei revealed three signals of CCND1 at 11q13, but two signals of BIRC3 at 11q22 and MLL at 11q23, indicating that r(11) contained CCND1. Together with other reported cases, our results indicate that the gain of 11q as well as trisomy 18 may be among the recurrent chromosomal aberrations in IVLBCL. Furthermore, an additional ring chromosome 11 could be a novel mechanism leading to the gain of 11q.

Interstitial Duplication and Distal Deletion in a Ring Chromosome 13 with Pulmonary Atresia and Ventricular Septal Defect: A Case Report and Review of Literature

Abstract: We report on a newborn female infant with a unique ring chromosome 13. Prenatal findings include intrauterine growth restriction (IUGR); ventricular septal defect (VSD), overriding aorta, and pulmonary stenosis. Postnatal examination found mild dysmorphic features of flat fontanels and hypertelorism. Echocardiogram confirmed the diagnosis of Tetralogy of Fallot (TOF), pulmonary atresia (PA) and VSD. Cytogenetic analysis detected a mosaic pattern of a ring chromosome 13, monosomy 13 and dicentric ring chromosome in about 90%, 9% and 1% of blood lymphocytes, respectively. Oligonucleotide array comparative genomic hybridization (aCGH) analysis revealed a 28.476 Mb interstitial duplication of 13q14.11-q21.33 and a 10.217 Mb distal deletion of 13q33.2-q34. Review of the literature suggested three groups of ring chromosome 13 with variable phenotypes based on the size of 13q deletions and noted two cases of ring chromosome 13 with a distal deletion defined by genomic analysis. A heat map of ring chromosome 13 phenotypes was constructed. The present case represents a new group of ring chromosome 13 with compound segmental duplication and deletion. This study demonstrates the importance of genomic characterization of constitutional ring chromosome for better disease classification and phenotype correlation. [N A J Med Sci. 2013;6(4):208-212. DOI: 10.7156/najms.2013.0604208]

Supernumerary Ring Chromosome: An Etiology for Pallister-Killian Syndrome?

Abstract: Characterization of marker chromosomes before the introduction of array CGH (aCGH) assays was only based on their banding patterns (G, C, and NOR staining) and fluorescent in situ hybridization techniques. The use of aCGH greatly improves the identification of marker chromosomes in some cases. We describe an atypical case of Pallister-Killian syndrome (PKS) detected at prenatal diagnosis with a very unusual cytogenetic presentation: a supernumerary ring chromosome including two copies of 12p. A similar anomaly described in a postnatal patient suggests ring chromosome as a possible cause of PKS. Extra ring chromosomes might be a more common etiology for PKS than previously thought, given the difficulty in their characterization before the advent of aCGH.

G-banding and fluorescence in situ hybridization in childhood acute myeloid leukemia from South India.

Abstract: Background The current WHO classification of hematologic malignancies defines distinct entities of myeloid disorders based on the presence of recurrent cytogenetic abnormalities. Diagnostic clonal chromosomal abnormalities provide important prognostic information and are among the most important factors in predicting initial response to chemotherapy, duration of remission and overall survival. Methods This study analyzed chromosomal abnormalities in bone marrow aspirates of 50 children diagnosed with acute myeloid leuckemia (AML). Results The culture success rate was 94%, clonal chromosomal abnormalities constituted 62% and recurrent chromosomal abnormalities were 56%. In the favorable prognostic category, there were 51.6% of cases with t(8;21)(q22;q22), 16.1% had t(15;17)(q22;q21), and a total of 12.9% had chromosome 16 rearrangement. The adverse risk category showed a low frequency of t(9;11)(p22;q13); t(1;22)(p13;q13); inv(3)( q21q26); add 4(q35) and ring chromosome. According to fluorescent in situ hybridization (FISH) results in 16 cytogenetically normal patients, there were no CBFβ/MYH11 fusion genes observed in chromosome 16 rearrangements. Discussion Larger studies of this kind may provide more information about chromosome 16 rearrangements in cytogenetically normal patients. The present analysis suggests that both age and cytogenetics are important strategies for risk stratification (outcome). Additional laboratory parameters should also be considered in childhood AML.

Ring chromosome 15: expanding the phenotype.

Abstract: Summary: Ring chromosome 15: expanding the phenotype: Ring chromosome 15 is a rare disorder, with less than 50 cases reported in the literature to date. We report the clinical and cytogenetic evaluation of a patient with ring chromosome 15. Diagnostic tests including echocardiography, abdominal ultrasound, brain computerized tomography (CT), magnetic resonance imaging (MRI) and electroencephalogram (EEG) were done. Clinical examination of the patient revealed the characteristic features of ring chromosome 15, such as growth retardation, hypertelorism, frontal bossing, a highly arched palate, small hands and feet and cafe-au-lait spots. In addition, the patient presented with a mild intellectual disability, a congenital atrial septal heart defect, and abnormal EEG records. We also report 2 novel findings, which to our knowledge; have not been reported before in ring chromosome 15 patients: large areas of hyperpigmentation on the front of both legs and feet and hypogenesis of the corpus callosum. Cytogenetic studies using both conventional G-banding and fluorescence in situ hybridization (FISH) with a Sub Tel 15q probe confirmed the diagnosis of ring chromosome 15.Key-words: Ring chromosome 15 - FISH - Subtelomeric region - Hypogenesis of corpus callosum - Cafe-au-lait pigmentation.___INTRODUCTIONRing chromosomes usually arise from breaks at the ends of both chromosome arms, followed by fusion of the broken ends (25). They may also result from fusion of subtelomeric sequences or telomere-telomere fusion without deletion, leading to incomplete ring chromosome formation (2, 8). Ring chromosomes have been reported in all human chromosomes (24). The clinical phenotype of patients with ring chromosomes may be related to different factors as gene haploinsufficiency, duplications or the instability of the ring. However, the epigenetic factors due to the circular architecture of ring chromosomes should also be considered, since even complete ring chromosomes may result in phenotypic alterations (5).Ring chromosome 15 (r(l 5)} is a rare genetic disorder which was first described by Jacobsen and his colleagues (10). To our knowledge, less than 50 patients with r( 15) have been described in literature with a wide diversity of phenotypic presentation. The most common shared features in patients with ring (15) are: severe intrauterine growth retardation, microcephaly, hypertelorism, ear anomaly, high arched palate, intellec- tuai disability, clinodactyly and brachydactyly of the fifth finger, small hands and feet, and multiple hyperpigmented and/or hypopigmented spots (12). Severe phenotypes were also observed as congenital heart defects and renal anomalies, others presented with hypotonia, hydrocephaly, micrognathia, retinal abnormalities, behavioral disorders and speech delay. Hypogenitalism, cryptorchidism and azospermia were reported in males. On the contrary, female patients had normal sexual development and gonadal function, although uterine hypoplasia has been reported (1,18, 22, 24). A precise genotype-phenotype correlation of ring 15 chromosome is still difficult to be established because of the differences in the breakpoints, level of mosaicism and ring instability that resulted in a variable loss of genetic materials (6).CLINICAL REPORTWe report a 2 years old female patient complaining of failure to thrive and delayed milestones of development who was referred to the Department of Clinical Genetics, National Research Center, Egypt. She was the offspring of a non-consanguineous 24 and 27 years old mother and father, respectively. The pregnancy and delivery histories were unremarkable except for intrauterine growth retardation and low birth weight. On physical examination, the proband was alert, recognized the surrounding and able to follow commands. She had delayed milestones of development, could stand with support and vocalized with single syllable word.Her current weight was 5.8 kg (-4. …

Molecular and Phenotypic Characterization of Ring Chromosome 22 in Two Unrelated Patients

Abstract: We report on the cytogenetic and molecular characterization of a constitutional de novo ring chromosome 22 (r(22)) in 2 unrelated patients with emphasis on different hypotheses proposed to explain the phenotypic variability characterizing this genomic disorder. In both patients, molecular investigations using FISH and array-CGH techniques revealed a 22q terminal deletion involving the 22q13.33 critical region. The size of the deletion was estimated to at least 1.35 Mb in the first proband and to only 300 kb in the second. They both exhibited the major features of r(22) syndrome, but the first patient was more profoundly affected. He had a more severe phenotype, further complicated by behavioral anomalies, autistic-like features with abnormal EEG pattern and brain MRI profile. Haploinsufficiency of the SHANK3 gene, lying in the minimal critical region, is nowadays considered as responsible for most neurobehavioral anomalies. Nevertheless, phenotypic severity and occurrence of additional features in the first patient suggest a potential involvement of one or more specific gene(s) located proximally to SHANK3 (as PLXNB2, PANX2, ALG12 or MLC1), acting either independently of it or by regulating or promoting its expression and thus disrupting its function when deleted.

A Case of Autism with Ring Chromosome 14.

Abstract: Background: Autism is a complex neuropsychiatric disorder that manifests in early childhood. Although the etiology is unknown yet but, new hypothesis focused on identifying the key genes related to autism may elucidate its etiology. The main objective of the present study was to verify the value of karyotyping in autistic children and identifying association between chromosome abnormalities and autism. Methods: We examined the peripheral blood lymphocytes cell culture for cytogenetic alterations by GTG-banding technique. The investigation was carried out on 50 autistic patients referred by Pediatric neurologist to Cytogenetic Laboratory in Khorasan-e-razavi Province, Iran. Results: Using GTG-banding technique, the chromosome analysis of patients identified an unbalanced male karyotype with a r (14) in all 50 metaphases were examined. Conclusion: Since structural abnormalities may have a critical role in the etiology of autism, according to the region where is affected and number of related genes, therefore an outcome with wide spectrum of clinical manifestations could be expected. Furthermore by considering of recent study, the results indicated that there is an association between chromosome 14 with brain development and neurological disorders, but, in conclusion, it could not be suggested that in order to postulate cytogenetic testing in idiopathic autism patients, specifically screening for chromosome 14 which might has diagnostic value.

A Mosaic Ring Chromosome 21 in a Patient with Mild Intellectual Disability not Evidenced by Array-Cgh

Abstract: We report a case of a two year-old girl with persistent thrombocytopenia, syndactyly, and mild psychomotor delay with speech delay. Proband chromosomal analysis from peripheral blood detected a mosaicism with two cell lines: the first with a ring chromosome 21 46,XX,r (21) (88%), and the second 45,XX,-21 (12%). In uncultured cells the level of mosaicism was 15% for the 46,XX,r(21) cell line and 85% for the 45,XX,-21 cell line. A different level of mosaicism was detected on buccal smear cells with a r(21) in 94%, and monosomy 21 in 6% of cells. The findings in the different cell lines are consistent with loss of the ring chromosome in the blood line.

Two siblings with similar phenotypes: one of them had ring 20 chromosome.

Abstract: We present the electroclinical features and cytogenetic findings of 2 siblings with the ring 20 chromosome (r(20)) phenotype, one of which had r(20) mosaicism. A history of epilepsy or learning problems should be determined in family members, although these relatives had no ring formation in chromosome 20. Whether the clinical features result from possible deletions or ring formation is discussed.

Anal atresia, abnormal genitalia, and absent thumb: congenital malformations associated with mosaic ring chromosome 13.

Abstract: Because of the deletion of a segment of the chromosome during the formation of a ring, several clinical findings may be associated with ring chromosomes. Ring chromosome 13 is one of such disorders in which the genotype-phenotype correlation is stronger by virtue of the accumulating literature. It can be associated with multiple congenital abnormalities and severe mental retardation. We report a case with mosaic ring chromosome 13 whose prenatal ultrasound revealed bilateral ventriculomegaly. Anal atresia, unidentifiable external genitalia, and an absent thumb were observed in the postmortem examination.

45,X/46,X,r(Y)/46,X,dic r(Y) karyotype in an azoospermic male: a case report.

Abstract: Y chromosome abnormalities are frequently associated with male infertility. Men with ring Y chromosomes can present with sexual infantilism, ambiguous genitalia, hypospadias, or azoospermia. AZF microdeletions can result in spermatogenic defects in such patients. Here, we report an unusual karyotype of 45,X/46,X,r(Y)/46,X,dic r(Y) in an azoospermic man. However, the reason for this patient's azoospermia is not an AZF microdeletion but might be the abnormal structure of the r(Y) chromosome, the 45,X cell line, mosaicism of the 3 cell lines, or another unknown cause. In such cases, if the couple wishes to reproduce, cytogenetic, molecular and fluorescent in situ hybridization evaluations should be performed, and preimplantation genetic diagnosis should be used together with assisted reproductive technology.

Persisting ring chromosomes detected by mFISH in lymphocytes of a cancer patient—A case report

Abstract: We report the case of an 84 years old prostate cancer patient with severe side effects after radiotherapy in 2006. He was cytogenetically analysed in 2009 and in 2012 in a comparative study for individual radiosensitivity of prostate cancer patients. No other patient had clonal aberrations, but this patient showed ring chromosomes in the range of 21-25% of lymphocytes. He received 5 cycles of 5-fluorouracil/folic acid for chemotherapy of sigmoid colon carcinoma in 2003, three years before radiotherapy of prostate cancer. Blood samples were irradiated ex vivo with Cs-137 γ-rays (0.7Gy/min) in the G0-phase of the cell cycle. 100 FISH painted metaphases were analysed for the control and the irradiated samples each. Multicolour in situ hybridisation techniques like mFISH and mBand as well as MYC locus, telomere and centromere painting probes were used to characterise ring metaphases. Metaphase search and autocapture was performed with a Zeiss Axioplan 2 imaging microscope followed by scoring and image analysis using Metafer 4/ISIS software (MetaSystems). In 2009 chromosome 8 rings were found in about 25% of lymphocytes. Rings were stable over time and increased to about 30% until 2012. The ring chromosome 8 always lacked telomere signals and a small amount of rings displayed up to four centromere signals. In aberrant metaphases 8pter and 8qter were either translocated or deleted. Further analyses revealed that the breakpoint at the p arm is localised at 8p21.2-22. The breakpoint at the q arm turned out to be distal from the MYC locus at 8q23-24. We hypothesise that the ring chromosome 8 has been developed during the 5 FU/folic acid treatments in 2003. The long term persistence might be due to clonal expansion of a damaged but viable hematopoietic stem cell giving rise to cycling progenitor cells that permit cell survival and proliferation.

Ring chromosome with deletion 7q in acute myeloid leukaemia

Abstract: Cytogenetic abnormalities can be detected in approximately 50–60% of newly diagnosed adult patients with acute myeloid leukaemia (AML) Monosomy of the chromosome 7 (−7) and deletion of the long arm of the chromosome 7 (7q–) are considered as high cytogenetic-risk AML with a poor prognosis These abnormalities can occur, as a single chromosomal aberration, in approximately 8% of newly diagnosed AML We report an elderly patient with AML who had deletion 7q (7q–) along with ring chromosome, which was demonstrated in conventional cytogenetics and fluoresecent in-situ hybridisation techniques

Prenatal Diagnosis of 4p and 4q Subtelomeric Microdeletion in De Novo Ring Chromosome 4

Abstract: Ring chromosomes are unusual abnormalities that are observed in prenatal diagnosis. A 23-year-old patient (gravida 1, para 0) referred for amniocentesis due to abnormal maternal serum screening result in the 16th week of second pregnancy. Cytogenetic analysis of cultured amniyotic fluid cells revealed out ring chromosome 4. Both maternal and paternal karyotypes were normal. Terminal deletion was observed in both 4p and 4q arms of ring chromosome 4 by fluorescence in situ hybridization (FISH). However deletion was not observed in the WHS critical region of both normal and ring chromosome 4 by an additional FISH study. These results were confirmed by means of array-CGH showing terminal deletions on 4p16.3 (130 kb) and 4q35.2 (2.449 Mb). In the 21th week of pregnancy, no gross anomalia, except two weeks symmetric growth retardation, was present in the fetal ultrasonographic examination. According to our review of literature, this is the first prenatal case with 4p and 4q subtelomeric deletion of ring chromosome 4 without the involvement of WHS critical region. Our report describes the prenatal case with a ring chromosome 4 abnormality completely characterized by array-CGH which provided complementary data for genetic counseling of prenatal diagnosis.

Ring chromosome 14 syndrome presenting with intractable epilepsy: a case report

Abstract: Ring chromosome 14 syndrome is a rare genetic disorder. Typically, children with this syndrome have distinct facial features, development delay, microcephaly, seizures, ocular abnormalities, and recurrent respiratory infections. Epilepsy associated with ring chromosome 14 generally shows intractable seizures. We describe a six-month-old girl with ring chromosome 14 syndrome who presented with early-onset and drug-resistant seizures.

A Case with Mosaic Ring Chromosome 18

Abstract: The classical mode of ring chromosome formation is by break forming in both arms of the affected chromosome, fusion of the breaking points and loss of the distal fragments. Ring chromosome of the chromosome 18 is relatively common among ring chromosomes and the rate of having typical clinical sings of 18p and 18q sydromes vary related to the length of the deletion in 18p and 18q. Ring 18 phenotype is characterised by growth retardation, mental retardation and nonspecific abnormalities, also facial dysmorphism and malformations may be observed. Our case referred with congenital malformation, motor mental retardation (MMR), short stature, high palate, pectus excavatus was evaluated genetically. GTL banding and FISH methods were performed for the metaphase plaques obtained from peripheral lymphocytes cultered for 72 hours. The karyotype of the case was detected to be 46,XX,r(18)[25]/46,XX[75] and confirmed by FISH analysis.