Molecular cytogenetic diagnosis of a case with ring chromosome 18 syndrome / 中华医学遗传学杂志

Objective@#To explore the genetic basis for a child with developmental delay and congenital syndactyly.@*Methods@#G-banding chromosomal karyotyping and chromosomal microarray analysis (CMA) were performed on peripheral blood sample from the child.@*Results@#The child was ascertained as 46, XY, r(18)[52]/45, XY, ? 18[3]. A 18q21.32-q23 deletion was identified by CMA with a size of 19.85 Mb, which has encompassed 99 genes including CTDP1, TXNL4A, TSHZ1, PIGN, RTTN, TNFRSF11A, KDSR and CYB5A.@*Conclusion@#Clinical phenotype of the patient with ring chromosome 18 is associated with the size of the euchromatin loss and involved genes. As a useful complement to conventional karyotyping, CMA has provided an powerful tool for delineating complex chromosomal aberrations.

Síndrome del anillo del cromosoma 18: reporte de un caso y revisión de la literatura / Chromosome 18 ring syndrome: case report and review of the literature

El Síndrome del Anillo del Cromosoma 18 (18 [(r)18]) es un trastorno cromosómico que se incluye dentro de las anomalías estructurales desequilibradas donde dicho cromosoma se encuentra en forma de anillo el cual resulta de la pérdida simultánea de ambos segmentos terminales de los brazos corto y largo con la subsecuente fusión de sus extremos, constituyendo una estructura circular que microscópicamente se asemeja a un anillo, de allí su nomenclatura r (del inglés ring, que significa anillo). Tiene una incidencia de 1/40.000 nacidos vivos y hasta la fecha se han reportado aproximadamente entre 80 a 100 casos a nivel mundial sin embargo sólo existen alrededor de nueve reportes de r(18) en mosaico, aislado o asociado con otras alteraciones cromosómicas. A continuación, se presenta el caso de una paciente pediátrica con Síndrome del Anillo del cromosoma 18 estudiado y diagnosticado en la Unidad de Genética Médica de la Universidad Centroccidental Lisandro Alvarado en Barquisimeto, Venezuela, con la correspondiente revisión de la literatura relacionada con este síndrome(AU)

Chromosome 18 Ring Syndrome (18 [(r) 18]) is a chromosomal disorder that is included among the unbalanced structural anomalies in which chromosome 18 has a ring form which results from the simultaneous loss of both terminal segments of the short and long arms with the subsequent fusion of their ends forming a circular structure that microscopically resembles a ring, hence its nomenclature r (of the English ring, which means ring).18r Syndrome has an incidence of 1/40,000 live births; to date approximately 80-100 cases worldwide have been reported. There are only about nine reports of r(18) in mosaic, isolated or associated with other chromosomal alterations. We present a case of a pediatric patient with Chromosome 18 Ring Syndrome, evaluated and diagnosed in the Unidad de Genética Médica of the Universidad Centroccidental Lisandro Alvarado in Barquisimeto, Venezuela with the corresponding review of the literature(AU)

Clinical and cytogenetic characterization of a patient with tetrasomy 18p / Caracterización clínica y citogenética de un paciente con tetrasomía 18p

The 18p tetrasomy is a structural chromosomal abnormality with the presence of an extra isochromosome 18p, caused by a nondisjunction failure during maternal meiosis II. This additional i(18p) occurs in 1 of 180,000 live-born children worldwide, affecting males and females equally. It is characterized by craniofacial dysmorphisms; ears, nose and throat (ENT) abnormalities; musculoskeletal alterations; and global development delay. We aim to present the clinical and cytogenetic findings of a 3-year-10-month-old Latin American male with i(18p), to support the gene dosage effects, comparing his features with the ones reported in literature. This patient was product of the second pregnancy of a 39-year-old woman and the first son of a 49-year-old man. His main clinical features were microcephaly, facial dysmorphism, generalized hypotonia, and developmental delay. A blood sample of the patient was required to perform a GTG-banded karyotype and a fluorescence in situ hybridization (FISH) for chromosome 18 short arm. In addition, an SNP microarray analysis was carried out to detect genomic imbalances. Cytogenetic analysis revealed the presence of a metacentric supernumerary marker chromosome. The FISH study confirmed the origin of the marker chromosome by showing two signals for the 18p subtelomere and an intermediate signal for the 18 centromere. The microarray analysis showed a copy number gain of 18,385 Mb within the 18p.Tetrasomy tends to be a result of de novo events. The presence of the patient's isochromosome could be explained by advanced maternal age as it is known that this factor has high influence in isochromosome formation. Despite that there were no genes associated with the i(18p)'s clinical manifestations, these features are negatively correlated with dosage effects of the entire short arm. Physical and language therapy was recommended to the patient; the family received medical orientation, and awareness in family planning was raised.

La tetrasomía 18p es una anormalidad cromosómica estructural con la presencia de un isocromosoma extra 18p, causado por una no disyunción durante la meiosis materna II. Este adicional i(18p) ocurre en 1 de 180.000 niños nacidos vivos en todo el mundo, y afecta a hombres y mujeres por igual. Se caracteriza por dismorfias craneofaciales; anomalías en oídos, nariz y garganta (ENT); alteraciones musculoesqueléticas y del desarrollo global. Nuestro objetivo es presentar los hallazgos clínicos y citogenéticos de un varón latinoamericano de 3 años y 10 meses de edad con i(18p), para explicar los efectos de dosificación génica, comparando sus características con las reportadas en la literatura. Este paciente es producto del segundo embarazo de una mujer de 39 años y el primer hijo de un hombre de 49 años. Sus principales características clínicas fueron microcefalia, dismorfia facial, hipotonía generalizada y retraso global en el desarrollo. Se requirió una muestra de sangre del paciente para realizar un cariotipo con bandas GTG y una hibridación fluorescente in situ (FISH) para el análisis del brazo corto del cromosoma 18. Además, se llevó a cabo un análisis de microarreglos para detectar desequilibrios genómicos. El análisis citogenético reveló la presencia de un cromosoma supernumerario metacéntrico. Mientras que el estudio FISH confirma el origen del cromosoma marcador al mostrar dos señales para subtelómeros 18p y una señal intermedia para el centrómero 18. El análisis de microarreglos mostró una ganancia en el número de copias de 18,385 Mb dentro de la región 18p.La tetrasomía tiende a ser el resultado de eventos de novo. El isocromosoma del paciente podría explicarse por la edad materna avanzada, ya que se sabe que tiene una gran influencia en su formación. A pesar de que no hay genes asociados con las manifestaciones clínicas de i(18p), estas características están negativamente correlacionadas con los efectos de dosificación de todo el brazo corto. Se le recomendó terapia física y de lenguaje al paciente, la familia recibió orientación médica y se concientiza sobre la planificación familiar.

A Prenatal Case of Paracentric Inversion of Chromosome 18, inv(18)(q21.1q22)

Paracentric inversion of chromosome 18 is a rare cytogenetic abnormality. The vast majority of paracentric inversions are harmless and the offspring of paracentric inversion carriers have only slightly elevated risks for unbalanced karyotypes. However, various clinical phenotypes are seen due to breakpoint variation or recombination. We report a prenatally detected case of familial paracentric inversion of chromosome 18, inv(18)(q21.1q22), with normal clinical features.

A Prenatal Case of Paracentric Inversion of Chromosome 18, inv(18)(q21.1q22)

Paracentric inversion of chromosome 18 is a rare cytogenetic abnormality. The vast majority of paracentric inversions are harmless and the offspring of paracentric inversion carriers have only slightly elevated risks for unbalanced karyotypes. However, various clinical phenotypes are seen due to breakpoint variation or recombination. We report a prenatally detected case of familial paracentric inversion of chromosome 18, inv(18)(q21.1q22), with normal clinical features.

18p- syndrome: presentation of two cases with alobar holoprosencenphaly / Síndrome 18p-: presentación de dos casos con holoprosencefalia alobar

Introduction: The syndrome by deletion of the short arm of chromosome 18 is an infrequent syndrome, and its phenotypical variability makes it difficult to recognize. Its most frequently observed clinical characteristics include mental retardation, growth retardation, craniofacial malformations, including long ears, microcephaly and short neck; other less frequent associated malformations include holoprosencephaly. Case report: We present two patients with deletion of the short arm of chromosome 18, one presented a de novo mutation and the other was produced by a balanced translocation 6p/18p of maternal origin. Both patients presented alobar holoprosencephaly and cebocephaly, low-frequency clinical characteristics in this syndrome. Discussion: alobar holoprosencephaly is a malformation appearing in 10% of patients with deletion of the short arm of chromosome 18; we review the probable physiopathology of holoprosencephaly in this syndrome.

Introducción: El síndrome por deleción del brazo corto del cromosoma 18, es un síndrome poco frecuente y su variabilidad fenotípica lo hace difícil de reconocer. Las características clínicas observadas con más frecuencia incluyen retardo mental y de crecimiento, malformaciones craneofaciales que incluyen orejas largas, microcefalia y cuello corto; otras malformaciones asociadas menos frecuentes incluyen la holoprosencefalia. Reporte de casos: Se presentan dos pacientes con deleción del brazo corto del cromosoma 18, uno presentado de novo y otro producido por translocación balanceada 6p/18p de origen materno. Ambos pacientes presentaron holoprosencefalia alobar y cebocefalia, características clínicas de baja frecuencia en este síndrome. Discusión: La holoprosencefalia alobar es una malformación que se presenta en 10% de los pacientes con deleción del brazo corto del cromosoma 18; se revisa la probable fisiopatología de la holoprosencefalia en este síndrome.

Diagnóstico molecular de cromosomopatías fetales en Costa Rica / Molecular diagnosis of fetal chromosomal defects in Costa Rica

En Costa Rica, el diagnóstico de anomalías cromosómicas fetales se realiza solo mediante el análisis citogenético convencional de cromosomas obtenidos de cultivos celulares. Además de que la espera por los resultados puede ser larga, con alguna frecuencia fracasa el cultivo, por contaminación o por mala calidad de la muestra, o las figuras mitóticas no se pueden analizar, por lo que es necesario disponer de una metodología sencilla y barata, para obtener un diagnóstico prenatal rápido y fiable de trisomía 21, 18 ó 13, en embarazos de alto riesgo genético sometidos a amniocentesis o cordocentesis. Métodos: Se diseñaron tres PCRs multiplex para amplificar cuatro distintas repeticiones cortas en tándem, de cada uno de los cromosomas 21, 18 y 13. Se colectaron 93 muestras (88 líquidos amnióticos y 5 sangres fetales), recibidas en el laboratorio entre 2006 y 2008, con solicitud de análisis cromosómico. Los resultados de la reacción en cadena de la polimerasa cuantitativa fluorescente, fueron comparados con el cariotipo obtenido de las mismas muestras para demostrar la fiabilidad del ensayo. Resultados: Para este grupo de datos, la exactitud del ensayo fue del 100 por ciento y se consiguió obtener resultados en 48 horas. Se logró realizar el análisis de repeticiones cortas en tándem en el 77 por ciento de las muestras en las que no se pudo obtener crecimiento celular. Conclusión: La reacción en cadena de la polimerasa cuantitativa fluorescente demostró ser una metodología sencilla, fiable y rápida, por lo que podría convertirse en una herramienta complementaria del análisis cromosómico convencional. La obtención de resultados rápidos en casos de diagnóstico prenatal podría disminuir el periodo de ansiedad parental por la espera de los resultados, así como permitir un mejor abordaje terapéutico de los fetos afectados.

In Costa Rica, the diagnosis of chromosomal fetal anomalies is realizedonly by conventional cytogenetic analysis of chromosomes obtained from cellular cultures. The waiting for the results can be long. Moreover with some frequency culture fails due tocontamination or bad quality of the sample or they cannot be analyzed. This makes it necessary to have a simple and cheap methodology to obtain an accurate and rapid fetal diagnosis of trisomy 21, 18 or 13, in pregnancies of high genetic risk submitted to amniocentesis or cordocentesis. Materials and methods: Three multiplex PCRs were designed to amplify four different short tandem repeats of each of the chromosomes 21, 18 and 13. There were collected 93 samples (88amniotic fluids and 5 fetal bloods), received in the laboratory between 2006 and 2008 with request ofor chromosomal analysis. The results of the quantitative fluorescent PCR werecompared with the obtained cariotype of the same samples to stablish the accuracy demonstrate the reliability of the assay. Results: Accuracy of the assay was 100% and it was possible to obtain results within 48 hours.STRs analysis could be made in 77% of the samples where the cellular culture could not be done. Conclusion: The quantitative fluorescent PCR demonstrated to be a simple, accurate and rapid methodology, from what it might turn into a complementary tool of the chromosomal conventional analysis. The securing of rapid results in cases of antenatal diagnosis might diminish the period of anxiety parental for the waiting of the results, as well as to allow a better therapeutic management of the affected fetuses.

Seckel syndrome with chromosomal 18 deletion.

Four case records of patients with Seckel Syndrome (SS) were retrieved. Typical of bird headed dwarfism was seen in all. Chromosome 18 deletion was seen in one child with SS. MRI abnormalities were detected in 3 patients. Cytogenetic studies and neuroimaging is likely to provide important diagnostic and prognostic information.

A Case of De Novo 18p Deletion Syndrome with SensorineuralHearing Loss: A case report

Chromosome 18p deletion syndrome is one of the most frequent autosomal abnormalities with more than 150 reported cases in the world and 7 reported cases in South Korea. Frequent clinical features of 18p deletion syndrome include intellectual disability, growth retardation, and dysmorphic features including ptosis. To the best of our knowledge, sensorineural hearing loss has not been reported in the 18p deletion syndrome until now. A case with sensorineural hearing impairment associated with hypoplasia of bilateral cochlear nerves is presented in this paper. The sensorineural hearing impairment seen in this case could be related with deleted gene(s) located in the short arm of chromosome 18 or be an independent feature unrelated with 18p deletion. Further case reports are required in order to better define the relation between sensorineural hearing loss and the 18p deletion syndrome.

The Prognostic Significance of Chromosome 18 Monosomy in the Colon Cancer: Correlations with the Expressions of Smad4 and TGF-beta Receptor II Proteins

PURPOSE: Chromosomal instability of chromosome 18 and inhibition of the transforming growth factor beta (TGF-beta) signaling pathway, which is mediated through Smad4, play important roles in the tumorigenesis of colon cancer. This study evaluated the value of the expression of chromosome 18 monosomy in colon cancer as a prognostic factor and its correlations with the expressions of Smad4 and TGF-beta receptor II proteins. METHODS: We analyzed the rate of the expression of chromosome 18 monosomy in 66 colon cancers with using chromogenic in situ hybridization (CISH) and we evaluated its value as a prognostic factor by determining its correlation with the pathologic factors and immunohistochemical expressions of Smad4 and TGF-beta receptor II proteins. RESULTS: Of the 66 colon cancers, monosomy of chromosome 18, as determined by CISH, was observed in 18 cases (27.3%), and the decreased expression of Smad4 and TGF-beta receptor II proteins was observed in 30 cases (45.5%) and 25 cases (37.9%), respectively. The monosomy of chromosome 18 and the decreased expression of Smad4 proteins showed statistically significant correlations with the histologic differentiation, the presence of tumor emboli, the nodal status and the stage. The decreased expression of TGF-beta receptor II proteins had statistically significant correlations with the histologic differentiation, the T-stage, the nodal status and the stage. The monosomy of chromosome 18 showed a statistically significant correlation with the decreased expression of Smad4 and TGF-beta receptor II proteins. CONCLUSION: These results suggested that chromosome 18 monosomy may have prognostic value for colon cancer.

Clinical and Cytogenetic Analysis of Children with Maternal Chromosomal Balanced Translocation / 소아과

PURPOSE: Parents' genetic information plays an important role in their children's genetic expression. Human chromosome has 23-paternal chromosomes and 23-maternal chromosomes. Parental chromosomal translocation can induce clinical problems in their children because of imbalance in genetic information. We intent to analyze the cytogenentic and clinical features about children with maternal balanced translocation between chromosome 15 and 18. METHODS: We detected by one family's FISH study of chromosome 15. We have evaluated children born to clinically normal parents about peripheral bood analysis, endocrine, metabolic, radiologic study, electroencephalogram and social & intelligence scale. and We analysis their clinical manifestation by hospital records. RESULTS: Patient's father and elder sister are normal clinically and genetically. Her mother's chromosome show balanced translocation, 46, XX, t (15; 18) (p11.2; p11.3). One child has 46, XX, der (18) t (15; 18) (p11.2; p11.3), mental retardation, growth retardation, speech & social developmental delay, recurrent infection and mild mitochondria dysfunction. Her young brother has 46, XY, der (15) t (15; 18) (p11.2; p11.3), mental retardation, aggressive behavior, obesity and speech developmental delay. CONCLUSION: In this study we observed the children with developmental delay, dysmorphic facial features, mental retardation, growth retardation associated with growth hormone deficiency and aggressive behavior due to unbalanced translocation between chromosome 15 and 18.