Practice patterns of prenatal and perinatal testing in Canadian cytogenetics laboratories.

OBJECTIVE: To survey patterns of practice in Canadian cytogenetics laboratories and evaluate whether newer technologies have influenced testing algorithms for the detection of common aneuploidies and other genomic imbalances in the prenatal and perinatal settings. METHODS: Cytogenetics laboratories across Canada were invited to participate in two patterns-of-practice surveys: one in 2016 and one in 2019. They were asked to identify the prenatal and perinatal specimen types tested at their facility and which testing methods were used for initial testing and for follow-up. RESULTS: All clinical laboratories performing prenatal testing offer rapid aneuploidy detection (RAD). Most laboratories also offer microarray analysis. A positive result is either followed up by karyotyping or no further testing is performed. For prenatal samples, a negative result may be followed up by microarray or karyotyping and is dependent on the reason for referral. For perinatal samples, availability of microarray to follow up a negative result is increasing. CONCLUSIONS: Since 2016, the availability of RAD as a first-line test in Canadian cytogenetics laboratories remains consistent, while microarray has become the preferred follow-up testing method over traditional karyotyping following a normal RAD result. Despite a universal healthcare system, disparities in prenatal and perinatal cytogenetic testing algorithms are apparent.

JAK2-mutated acute myeloid leukemia: comparison of next-generation sequencing (NGS) and single nucleotide polymorphism array (SNPa) findings between two cases

JAK2 mutations are rare in de novo acute myeloid leukemia (AML), and JAK2-mutated acute myeloid leukemia (AML) patients usually have a previous history of myeloproliferative neoplasms (MPNs). Current advances in laboratory techniques, such as single nucleotide polymorphism array (SNPa) and next-generation sequencing (NGS), have facilitated new insight into the molecular basis of hematologic diseases. Herein, we present two cases of JAK2-mutated AML in which both SNPa and NGS methods added valuable information. Both cases had leukemogenic collaboration, namely, copy-neutral loss of heterozygosity (CN-LOH), detected on chromosome 9. One of the cases exhibited both JAK2 and IDH2 mutations, most likely having originated as an MPN with leukemic transformation, while the other case was classified as a de novo AML with JAK2, CEBPA, and FLT3 mutations.

Interstitial 10q21.1q23.31 Duplication due to Meiotic Recombination of a Paternal Balanced Complex Rearrangement: Cytogenetic and Molecular Characterization.

Complex chromosomal rearrangements (CCRs) are structural aberrations involving more than 2 chromosomal breakpoints. They are associated with different outcomes depending on the deletion/duplication of genomic material, gene disruption, or position effects. Balanced CCRs can also undergo missegregation during meiotic division, leading to unbalanced derivative chromosomes and, in some cases, to affected offspring. We report on a patient presenting with developmental and speech delay, growth retardation, microcephaly, hypospadias, and dysmorphic features, harboring an interstitial 10q21.1q23.31 duplication, due to recombination of a paternal CCR. Application of several cytogenetic and molecular techniques allowed determining the biological bases of the rearrangement, understanding the underlying chromosomal mechanism, and assessing the reproductive risk.

[Research progress in lampbrush chromosomes and some suggestions for their use in genetics teaching].

Lampbrush chromosomes (LBCs) are transient giant transcripts that exist at the diplotene stage of the first meiotic division in female gametocytes of almost all animals except mammals. LBCs are named for their lampbrush-like structure, however, they received the lowest research attention in studies of three classical cytogenetic chromosomes. They have been excellent models for studying the structure, organization, transcription, and transcriptional processing of chromosomes during meiosis. Here we briefly summarized these studies and LBCs forming mechanism and also discussed their possible functions, such as providing enough transcriptional products for embryonic development by oocytes LBCs or polyploidy demonstrated by previous reports. Finally, we discussed the possibility of introducing this typical case into our genetics teaching to inspire students' interest in genetics.

Evidence of incipient speciation in astyanax scabripinnis species complex (teleostei: characidae)

Two populations of the Astyanax scabripinnis complex, isolated by a waterfall with over 100 meters depth and inhabiting different altitudes of the same river (1850 m a.s.l. and 662 m a.s.l.) were compared in reproductive data, geometric morphometry, tooth morphology, anal-fin rays counts, and karyotype, in order to test the hypothesis of speciation between the two populations. The results in the geometric morphometry analysis showed differences between the populations. Discriminant function analysis (DFA) and canonical variance analysis revealed sexual dimorphism. Secondary sexual characters, such as hooks in the anal fin rays of the males are absent in the lower altitude population. Both populations had the same macro karyotype structure, except for the absence of B chromosomes in the lower altitude population. The fluorescence in situ hybridization showed differences for both markers (18S rDNA and 5S rDNA), and reproductive data suggests pre-zygotic reproductive isolation among the two populations. The data showed the absence of gene flow, indicating that an incipient speciation process has occurred, which leads the two populations to follow independent evolutionary pathways.

Duas populações do complexo Astyanax scabripinnis isoladas por uma queda d´água de mais de 100 metros de altura e localizadas em diferentes altitudes do mesmo rio (662 m e 1850 m a.s.l.) foram comparadas através de dados de reprodução, cariótipo, morfometria geométrica, morfologia dentária, e número de raios da nadadeira anal, de modo a testar a hipótese de especiação entre as duas populações. Os resultados de morfometria geométrica mostraram diferenças entre as populações. A análise da função discriminante (DFA) e a análise de variância canônica (CVA) demonstraram a presença de dimorfismo sexual. Caracteres sexuais secundários, como ganchos em raios da nadadeira anal dos machos, estão ausentes na população de menor altitude. Ambas as populações têm a mesma macro estrutura cariotípica, exceto pela ausência de cromossomos B na população de menor altitude. A hibridação in situ mostrou diferenças para ambos os marcadores (rDNA 18S e rDNA 5S), e os dados de reprodução sugerem isolamento reprodutivo pré-zigótico entre as duas populações. Os dados mostram ausência de fluxo gênico, indicando que ocorreu um processo de especiação incipiente, o que leva as duas populações seguirem vias evolutivas independentes.

Histiocitoma fibroso angiomatoide Presentación de un caso y revisión de la literatura / Angiomatoid fibrous histiocytoma. A case report and a review of the literature

El histiocitoma fibroso angiomatoide es una neoplasia mesenquimal de malignidad intermedia e histogénesis incierta que se da frecuentemente en las extremidades de niños o adultos jóvenes. Su morfología es peculiar, y está constituida como una lesión circunscrita de células fusiformes, infiltrado linfoplasmocitario periférico, cavidades quísticas rellenas de sangre y frecuente expresión de desmina. Nosotros presentamos un nuevo caso y revisamos la literatura, en particular con respecto a acontecimientos genéticos, de diferenciación, morfológicos, inmunohistoquímicos y de diagnóstico diferencial (AU)

Angiomatoid fibrous histiocytoma is a mesenchymal neoplasm of intermediate grade malignancy which is most commonly found in the extremities of children and young adults. Its histogenesis is uncertain and its morphology is unusual as it is a circumscribed lesion with spindle cells, peripheral lymphoplasmacytic infiltrate, blood-filled cystic cavities and frequent desmin expression. We report a new case and review the literature, paying special attention to genetic developments, differentiation, morphology, immunohistochemistry and differential diagnosis (AU)

Diagnóstico prenatal en la provincia de Girona en el período 1999-2009 / Prenatal diagnosis in the Girona area in the period 1999-2009

Objetivo. El objetivo de este trabajo es dar una visión global del uso y evolución del diagnóstico citogenético prenatal en la provincia de Girona en el período 1999-2009 y relacionar el diagnóstico citogenético con el cribado prenatal de aneuploidías. A partir de los datos recogidos se obtuvieron diversos indicadores presentados básicamente en forma de gráficos y tablas descriptivas. Resultados. Los resultados obtenidos indican lo siguiente: el uso del diagnóstico citogenético prenatal y posnatal aumentó a través del tiempo. El cribado prenatal de aneuploidías de procedencia pública en el período 1999-2009 mostró una tendencia creciente hasta el año 2005 y decreciente hasta el año 2009, cuando volvió a aumentar ligeramente. En pacientes del PASSIR Gironès-Pla de l’Estany la detección de la trisomía 21 fue del 88,9% en el cribado del primer trimestre y del 45% en el del segundo trimestre. La tasa media de detección de los cariotipos prenatales anómalos fue del 1,4% sin una tendencia temporal clara. Conclusiones. Las conclusiones principales son: - Se constata un aumento del uso del diagnóstico citogenético en el período 1999-2009. - La casuística de anomalías cromosómicas coincide con la bibliografía. - La sustitución del cribado del segundo trimestre por el del primer trimestre ha supuesto un incremento importante en la detección de aneuploidías. -La contribución de las pruebas de cribado prenatal es importante(AU)

Objective. The main goal of this research is to give a broad view of the use and evolution of prenatal cytogenetic diagnosis in Girona province between 1999 and 2009 and linking prenatal cytogenetic diagnosis with aneuploidy prenatal screening. The information collected allowed several indicators to be extracted, primarily presented as descriptive tables and charts. Results. The results show as follows: The use of prenatal and postnatal cytogenetic diagnosis increased in the mentioned period. The evolution of demand for aneuploidy prenatal screening in public health services during 1999-2009 showed an upward trend until 2005. From then on, it varied following a downward path until 2009, when it had a slight increase. Among PASSIR Gironès-Pla de l’Estany patients, detection of trisomy 21 through first-trimester screening was 88.9%, and through second-trimester screening was 45%. The average detection rate of abnormal prenatal karyotyping was 1.4%, with no clear trend in the above mentioned period. Conclusions. The main conclusions of this work are the following: - A rise in the use of cytogenetic diagnosis has been detected in Girona province between 1999 and 2009. - Case studies of chromosome abnormalities match the literature consulted. - Moving from second-trimester to first-trimester screening has meant a significant increase in aneuploidy detections. - Prenatal cytogenetic diagnosis is seen as an interdisciplinary field in which the extent of prenatal screening tests is crucial(AU)

Mosaicos cromosómicos en vellosidad corial / Chromosomal mosaicism in chorionic villi

Introducción. El estudio de vellosidades coriales comprende realizar 2 cultivos celulares que pueden no tener resultados coincidentes. Estas discrepancias pueden ser debidas a mosaicos citogenéticos de origen in vivo o in vitro. En este trabajo nos planteamos analizar los cariotipos en mosaicos, ligado con los rendimientos de los cultivos celulares y los resultados citogenéticos. Material y métodos. Se han analizado 2.360 muestras prenatales y 510 de vellosidades de abortos. Con las muestras prenatales se efectúan rutinariamente 2 cultivos celulares, cultivo corto y cultivo largo, y para los abortos además se han estudiado muestras de restos fetales. Resultados. El porcentaje de muestras con resultado citogenético para el grupo prenatal fue del 99,9% y para el grupo de abortos del 87,1%. El porcentaje de anomalías cromosómicas en el grupo prenatal fue del 10,6% siendo las aneuploidías comunes (trisomías 13, 18, y 21) las más frecuentes, y para el grupo de abortos fue del 55,1% siendo las aneuploidías no-comunes las más frecuentes. El porcentaje de cariotipos en mosaico para el grupo prenatal fue del 3,1% y para el grupo de abortos del 6,8%. El mosaico confinado a la placenta tipo ii fue el más frecuente. Conclusiones. Para el estudio de los mosaicos en vellosidades coriales la mejor estrategia es realizar los 2 cultivos paralelos en muestras prenatales y los 3 cultivos en muestras de abortos. Teniendo en cuenta el riesgo que asume la pareja ante una prueba invasiva, es nuestro deber dar el resultado citogenético más completo posible(AU)

Introduction. The study of chorionic villus samples comprises performing two cell cultures that may not have matching results. These discrepancies may be due to cytogenetic mosaics of in vivo or in vitro origin. This study included analysing the karyotypes in mosaics, associated with the cell culture and cytogenetic results. Material and methods. Prospective study based on the analysis of 2,360 chorionic villus samples and 510 spontaneous abortion samples. Two cultures were routinely performed on the prenatal samples (short and long), as well as on the abortion samples. Results. The success rate was 99.9% in the prenatal group, and 87.1% in the abortion group. The percentage of chromosomal anomalies in the prenatal group was 10.6%, with the common aneuploidies (trisomy 13, 18, and 21) being the most frequent. In the abortions group there 55.1% anomalies, with uncommon aneuploidy the most frequent. The percentage of mosaicism in the prenatal group was 3.1%, and it was 6.8% in the abortion group. The confined placental mosaicism type ii was the most frequent. Conclusions. For the study of the mosaicism in chorionic villi samples the best strategy is to perform 2 prenatal samples cultures in parallel, and 3 abortion samples cultures. Given the risk to the mother and child using this invasive test, it is our duty to give the most comprehensive cytogenetic results achievable(AU)

DNA barcode of parodontidae species from the La Plata river basin - applying new data to clarify taxonomic problems

In the past years, DNA barcoding has emerged as a quick, accurate and efficient tool to identify species. Considering the difficulty in identifying some Parodontidae species from the La Plata basin and the absence of molecular data for the group, we aimed to test the effectiveness of DNA barcoding and discuss the importance of using different approaches to solve taxonomic problems. Eight species were analyzed with partial sequences of Cytochrome c oxidase I. The mean intraspecific K2P genetic distance was 0.04% compared to 4.2% for mean interspecific K2P genetic distance. The analyses of distance showed two pairs of species with K2P genetic divergence lower than 2%, but enough to separate these species. Apareiodon sp. and A. ibitiensis, considered as the same species by some authors, showed 4.2% genetic divergence, reinforcing their are different species. Samples of A. affinis from the Uruguay and Paraguay rivers presented 0.3% genetic divergence, indicating a close relationship between them. However, these samples diverged 6.1% from the samples of the upper Paraná River, indicating that the latter represents a potentially new species. The results showed the effectiveness of the DNA barcoding method in identifying the analyzed species, which, together with the morphological and cytogenetic available data, help species identification.

Nos últimos anos o DNA barcoding surgiu como uma ferramenta rápida, precisa e eficiente para identificar espécies. Considerando a dificuldade na identificação de algumas espécies de Parodontidae da bacia do rio da Prata e da ausência de dados moleculares para o grupo, testamos a eficácia do código de barras de DNA e discutimos a importância do uso de diferentes abordagens para resolver problemas taxonômicos. Oito espécies foram analisadas com sequencias parciais do gene citocromo c oxidase I. A distância genética média K2P intraespecífica foi de 0,04% comparado com 4,2% para distância genética média K2P interespecífica. As análises de distância mostraram dois pares de espécies com divergência genética K2P inferior a 2%, mas o suficiente para separar estas espécies. Apareiodon sp. e A. ibitiensis, consideradas a mesma espécie por alguns autores, mostraram 4,2% de divergência genética, confirmando serem espécies diferentes. Amostras de A. affinis dos rios Uruguai e Paraguai apresentaram 0,3% de divergência genética, indicando um maior grau de relação entre elas, no entanto, esses exemplares divergiram em 6,1% em relação aos exemplares do alto rio Paraná, o que indica que estes últimos representam uma espécie potencialmente nova. Os resultados mostraram a eficácia do método de DNA barcoding na identificação das espécies analisadas, os quais, em conjunto com os dados morfológicos e citogenéticos disponíveis auxiliam na identificação inequívoca das espécies.

Caracterização citogenética para identificação dos níveis de ploidia em cinco espécies do gênero Mentha L / Citogenetic characterization to determination of ploidy level on five Mentha L. species

Neste trabalho foi feita a caracterização citogenética da: microsporogênese, tétrades, estimativa da viabilidade do pólen pelo método de coloração e contagem do número máximo de nucléolos por célula interfásica, para identificação dos níveis de ploidia, em cinco espécies do gênero Mentha L. Foram coletadas inflorescências em 30 plantas de cada espécie, em duas florações sucessivas, nos anos 2006 e 2007. As inflorescências foram tratadas em etanol-ácido acético (3:1), em temperatura ambiente durante seis horas, transferidas para álcool 70% (v/v) e conservadas em geladeira até análise. Nas análises da microsporogênese, tétrades e pólen o corante usado foi carmin propiônico 2% e na identificação dos nucléolos nitrato de prata (AgNO3). Os resultados demonstraram que as cinco espécies são poliplóides. M. crispa heptaplóide (2n=7x=84) com 11 nucléolos, M. spicata tetraplóide (2n=4x=48) com 8 nucléolos, M.x gentilis pentaplóide (2n=5x=60) com 12 nucleólos, M. piperita e M.x piperita ambas hexaplóides (2n=6x=72) com 8 e 9 nucléolos respectivamente. M. spicata e M. crispa mantiveram as mais altas porcentagens de células normais na microsporogênese, na formação de tétrades e na estimativa da viabilidade do pólen por coloração, sugerindo maior estabilidade meiótica quando comparados aos demais poliplóides estudados.

The cytogenetic characterization of five species of Mentha L. genus, including the data: regularity of microsporogenesis and tetrads, and polen viability, using the coloration method and the counting of the maximum number of nucleolus by interphasic cell were carried out in this study to identify the ploid levels. These analyses were performed from inflorescences collected in 30 plants of each species, during two successive florations in 2006 and 2007. Inflorescences were treated in 3:1 ethanol:acetic acid mixture at room temperature during six hours, then transferred to 70%(v/v) ethanol solution and refrigerated until the analysis. For microsporogenis, tetrad and pollen analysis, we used carmine propionic 2% (m/v) and for nucleolus identification, we used AgNO3 solution. It was possible to observe that all five species were polyploids. M. crispa heptaploid (2n=7x=84) with 11 nucleolus, M. spicata tetraploid (2n=4x=48) with 8 nucleolus, M. x gentilis pentaploid (2n=5x=60) with 12 nucleolus, M. piperita and M. x piperita both hexaploid (2n=6x=72) with 8 and 9 nucleolus respectively. M. spicata and M. crispa kept the highest percentual values of normal cells in microsporogenesis as well as in tetrads formation and pollen viability, suggesting a higher meiotic stability when compared to the other polyploids studied.

Multicolour interphase cytogenetics: 24 chromosome probes, 6 colours, 4 layers.

From the late 1980s onwards, the use of DNA probes to visualise sequences on individual chromosomes (fluorescent in-situ hybridisation - FISH) revolutionised the study of cytogenetics. Following single colour experiments, more fluorochromes were added, culminating in a 24 colour assay that could distinguish all human chromosomes. Interphase cytogenetics (the detection of chromosome copy number in interphase nuclei) soon followed, however 24 colour experiments are hampered for this application as mixing fluorochromes to produce secondary colours produces images that are not easily distinguishable from overlapping signals. This study reports the development and use of a novel protocol, new fast hybridising FISH probes, and a bespoke image capture system for the assessment of chromosome copy number in interphase nuclei. The multicolour probe sets can be used individually or in sequential hybridisation layers to assess ploidy of all 24 human chromosomes in the same nucleus. Applications of this technique are in the investigation of chromosome copy number and the assessment of nuclear organisation for a range of different cell types including human sperm, cancer cells and preimplantation embryos.

Testing hygrometers used in cytogenetics laboratories for metaphase preparation.

This protocol describes procedures for checking small laboratory hygrometers for accuracy at three relative humidity (rh) levels. The work arose out of the need to provide laboratory assessors with documentary evidence that the hygrometer used to monitor humidity in the vicinity of the laboratory where medical cytogenetics testing slides are prepared and dried in the ambient environment is reproducible and sufficiently accurate. The procedure is based upon the physicochemical principle that when water or certain saturated salt solutions are placed into a sealed environment, the humidity will equilibrate to well defined levels. We choose to check our hygrometers at three points: 95%, 75%, and 33% rh, using distilled water, saturated sodium chloride solution, and saturated magnesium chloride solution, respectively. Our results have demonstrated that the procedure is convenient and of sufficient accuracy to be fit for this annual hygrometer validation purpose. The procedure takes 24 hr per relative humidity point checked.

Malformaciones esqueléticas: diagnóstico ecográfico y resultados perinatales / Skeletal malformations: ultrasound diagnosis and perinatal results

Introducción. la incidencia de las alteraciones del desarrollo de las estructuras osteocartilaginosas fetales es baja. Aunque su diagnóstico ecográfico es sencillo, especialmente en las osteocondrodisplasias letales, llegar a un diagnóstico etiológico es complicado. El objetivo del presente trabajo es presentar los hallazgos ecográficos y resultados perinatales de las malformaciones esqueléticas diagnosticadas en nuestro centro. Material y métodos. estudio descriptivo retrospectivo de serie de casos. Se incluyeron las malformaciones esqueléticas diagnosticadas prenatalmente en la Sección de Medicina Fetal del Hospital General Universitario Gregorio Marañón (noviembre de 2004-febrero de 2010). Los casos se clasificaron en defectos del esqueleto axial o radial, tanto focales aislados como cuadros generalizados de displasias óseas. Se analizaron la edad gestacional al diagnóstico, los defectos congénitos asociados y los resultados perinatales. Resultados. durante el período de estudio se registraron 56 casos. La edad gestacional media al diagnóstico fue de 23,7 semanas (rango 12-37; desviación estándar 7,25). Veintiséis (46,4%) se presentaron como malformación aislada; 14 (25%) asociadas a otras malformaciones, y 16 (28,6%) en el contexto de un síndrome polimalformativo. De los 29 (51,8%) casos en que se realizó estudio citogenético, en 10 (34,5%) se diagnóstico una cromosomopatía. En 40 casos (71,4%) el diagnóstico fue de anomalía focal del esqueleto radial; en 5 (8,9%), de anomalía del esqueleto axial, y en 14 (25%), de osteocondrodisplasia. Sólo en 11 casos se estableció un diagnóstico nosológico. La supervivencia en el período neonatal fue del 61,1% (33/54). Conclusiones. las malformaciones esqueléticas se asocian frecuentemente a otros defectos congénitos, de difícil diagnóstico etiológico y con una alta tasa de resultado perinatal adverso(AU)

Introduction. The incidence of disorders in the development of foetal bone and cartilage structures is low. Although ultrasound diagnosis is easy, especially in lethal skeletal dysplasias, to reach an aetiological diagnosis can be difficult. The aim of this study was to present the ultrasound findings and perinatal outcomes of skeletal malformations diagnosed in our centre. Material and methods. A retrospective descriptive study of case series. Skeletal malformations prenatally diagnosed in the Foetal Medicine Unit at the Gregorio Marañón General University Hospital (HGUGM) Madrid between November 2004 and February 2010 were included. Cases were classified as axial or radial skeletal defects, including isolated defects, as well as generalised skeletal dysplasias. Gestational age at diagnosis, presence of associated congenital defects and perinatal outcome were recorded. Results. A total of 56 cases were included during the study period. The mean gestational age at diagnosis was 23.7 weeks (range 11-36, standard deviation 7.25). Twenty-six (46.4%) occurred as an isolated malformation, 14 (25%) associated to other malformations, and 16 (28.6%) as a multiple malformation syndrome. Among the 29 (51.8%) cases in which a cytogenetic study was performed, 10 (34.5%) had a chromosomal abnormality. The diagnosis was a radial skeletal focal anomaly in 40 cases (71.4%); anomalies of the axial skeleton in 5 (8.9%); and osteochondrodysplasia in 14 (25%). A nosological diagnosis was established in only 11 cases. Neonatal survival was 61.1% (33/54). Conclusions. Skeletal malformations are often associated with other congenital defects. Aetiological diagnosis may be extremely difficult and the rate of adverse perinatal outcomes is high(AU)

The assessment of array comparative genomic hybridization in complex karyotype analyses.

Molecular-cytogenetic methods were used to analyse and specify complex genome rearrangements in malignant cells. Twelve samples of bone marrow cells were collected from patients with myelodysplastic syndromes (MDS). The complex karyotypes were examined by multicolour fluorescence in situ hybridization (mFISH), high-resolution multicolour banding (mBAND) and array comparative genomic hybridization (aCGH). For aCGH, DNA was isolated from fixed bone marrow cells in methanol and acetic acid and amplified by whole-genome amplification. Three samples were analysed by the oligonucleotide array NimbleGen on the basis of full service. BAC-based Haematochips (BlueGnome) were used for the other nine samples. Sensitivity and detection limits of both methods were compared. The results obtained by mFISH/mBAND were in most cases confirmed by the microarray technique. aCGH detected 43 unbalanced chromosomal changes that were also identified by classical cytogenetics and FISH. Moreover, aCGH discovered 14 additional changes. Cryptic amplifications and deletions were characterized with a resolution of 0.5 Mb. In one bone marrow sample with suspected monosomy 5 detected by conventional cytogenetic analysis, aCGH revealed a 22.3 Mb region of chromosome 5 inserted in another autosome within the complex karyotype. Amplified DNA was successfully used for aCGH in 11 out of 12 cases, improving resolution of unbalanced chromosomal aberrations. The combination of both approaches brought more detailed description of complex karyotypes and is highly recommended.

Combing genomic DNA for structural and functional studies.

Molecular combing is a process whereby single DNA molecules bind by their extremities to a silanised surface and are then uniformly stretched and aligned by a receding air/water interface (1). This method, with a high resolution ranging from a few kilobases to megabases, has many applications in the field of molecular cytogenetics, allowing structural and functional analysis at the genome level. Here we describe protocols for preparing DNA for combing and for the use of fluorescent hybridisation (FH) applied to combed DNA to conduct physical mapping or genomic structural analysis. We also present the methodology for visualising and studying DNA replication using combed DNA.

Genética molecular del cáncer renal: utilidad en pronóstico y posibilidades terapéuticas / Molecular genetics of renal cancer: usefulness in prognosis and therapeutic possibilities

El cáncer renal tiene una incidencia del 3% del total de las neoplasias en adultos, y puede ser tanto de origen hereditario como esporádico. Histológicamente se clasifica en 5 tipos principales. Las técnicas actuales de citogenética y biología molecular han permitido conocer con más detalle algunos de los sucesos genéticos iniciales que causa la patogenia de los tipos mayoritarios como, por ejemplo, que un defecto en el cromosoma 3p está implicado en el desarrollo del carcinoma de células claras (ccRCC) o que en un 13% de los RCC de tipo papilar está mutado el gen c-MET (cromosoma 7), y en el resto de cánceres de este tipo existe duplicación de este mismo cromosoma, o que, en los oncocitomas la pérdida de los cromosomas 1 y/o 14 podría representar el suceso inicial. Aparte de estos defectos, el conocimiento de otros genes y alteraciones cromosómicas implicados, junto con otros factores, permite definir de manera aproximada el pronóstico en cada caso. Debido a que este tipo de cáncer desarrolla metástasis rápidamente, las terapias actuales, como la cirugía y el uso de interleucina (IL) 2, son poco eficaces y sólo consiguen alargar en unos meses la supervivencia del paciente. Aunque se están ensayando nuevas terapias, es necesario un conocimiento más profundo de los procesos moleculares implicados para obtener el éxito deseado tanto en el diagnóstico precoz como en el pronóstico y el tratamiento de la enfermedad(AU)

Renal cancer has a 3% incidence of all neoplasms in adults and it can be of hereditary or sporadic origin. Histologically, it is classified into 5 main types. The current cytogenetic and molecular biology techniques allow some of the initial genetic events responsible for the main types of pathogenesis to be studied in more detail, such as the implication of a defect in chromosome 3p in the development of clear cell renal cell carcinoma (ccRCC), or the presence of the mutated c-MET gene (chromosome 7) in 13% of papillary RCCs and the presence of the same chromosome duplication in the rest of these types of cancer, or the loss of chromosomes 1 and/or 14 which could represent the initial event in oncocytomas. Apart from these defects, knowledge other genes involved and chromosomic defects, as well as other factors, may enable an approximate prognosis to be made in each case. As the metastatic process in this cancer type develops very early, the current therapies, such as surgery and the use of IL-2, are not very effective and they only manage to extend patient survival by a few months. Although newer therapies are being assessed, a deeper knowledge about the molecular processes involved is necessary to obtain the desirable success both in the early diagnosis, as well as the prognosis and treatment of the disease(AU)

A support vector machine classifier for recognizing mitotic subphases using high-content screening data.

High-content screening studies of mitotic checkpoints are important for identifying cancer targets and developing novel cancer-specific therapies. A crucial step in such a study is to determine the stage of cell cycle. Due to the overwhelming number of cells assayed in a high-content screening experiment and the multiple factors that need to be taken into consideration for accurate determination of mitotic subphases, an automated classifier is necessary. In this article, the authors describe in detail a support vector machine (SVM) classifier that they have implemented to recognize various mitotic subphases. In contrast to previous studies to recognize subcellular patterns, they used only low-resolution cell images and a few parameters that can be calculated inexpensively with off-the-shelf image-processing software. The performance of the SVM was evaluated with a cross-validation method and was shown to be comparable to that of a human expert.

Analysis of RNA recovery and gene expression in the epidermis using non-invasive tape stripping.

BACKGROUND: The recovery of RNA from the upper epidermis by tape stripping yields variable RNA mass but has not been evaluated for its dependence on anatomical location. Gene expression at different body locations and the origin of RNA recovered by tape stripping have not been investigated. OBJECTIVES: To characterize the recovery of RNA from different anatomical locations by tape stripping; to correlate the recovery of RNA and removal of barrier by tape stripping, as assayed by transepidermal water loss; and to investigate gene expression in the upper epidermis at different body locations. METHODS: Twelve subjects were tape stripped at 15 body locations. RNA mass was evaluated and gene expression assayed. Subjects were tape stripped 4, 8 and 12 times on the upper back and transepidermal water loss and RNA recovery assayed. RESULTS: Ranked by median RNA recovery, the following order was observed: mastoid>forehead>chest>upper back>mid back>cheek>lower back>deltoid>forearm>abdomen>ventral thigh>inner arm>shin>dorsal thigh>lower leg. Expression of the housekeeping gene mRNAs is found to be uniform and reproducible while IL-8 and TNFalpha mRNAs are expressed in different quantities both at different body sites within an individual and between individuals at a specific anatomical site. Data show a significant and high correlation between the number of tapes used to strip a site and transepidermal water loss but no strong correlation between transepidermal water loss and RNA recovery or number of tapes used to strip a site and RNA recovery. CONCLUSIONS: Subjects and anatomical location are shown to be significantly different for the ability to recover RNA by tape stripping. We hypothesize that RNA recovered by tape strip is not derived from corneocytes but from cells associated with the stratum corneum.

Trisomia parcial del cromosoma 6(q27): presentación de un caso / Partial trisomy of chromosome 6(q27): a case report

Presentamos un caso de un paciente de sexo masculino de 5 meses de edad, múltiple malformado. Mediante técnicas de citogenética clásica y bandeamiento G, se determino, trisomía parcial del brazo largo del cromosoma 6, (dup parcial 6 (q27). Una enfermedad cromosómica extremadamente rara, por lo que se busco una relación con otros casos similares reportados y la probable acción de los genes involucrados en esta región para la expresión de los signos clínicos reportados.

Measurement of cytogenetic damage in rodent blood with a single-laser flow cytometer.

The in vivo rodent micronucleus test is widely utilized to screen chemicals for genotoxic activity. Double-strand chromosome breaks or dysfunction of the mitotic spindle apparatus can lead to micronuclei formation in dividing cells. Erythrocytes have become the target population of choice, as precursor cells are continuously dividing and micronuclei are readily observable after extrusion of nuclei. The traditional method has been to stain peripheral blood or bone marrow smears and microscopically determine the frequency of micronucleated erythrocytes. Because these events are rare, the process is tedious and time consuming. This unit describes a procedure for fixing and staining rodent peripheral blood for flow cytometric enumeration. The combination of reagents provides for differential labeling and enumeration of four subpopulations: mature erythrocytes, micronucleus-containing mature erythrocytes, young erythrocytes (reticulocytes), and micronucleus-containing young erythrocytes. Malaria-infected rodent erythrocytes, which closely mimic micronucleus-containing erythrocytes, serve as a biological standard to facilitate rational and consistent equipment calibration.