Performance of conventional cytogenetic analysis on chorionic villi when only one cell layer, cytotrophoblast or mesenchyme alone, is analyzed.

OBJECTIVE: To provide an estimation of the probability of error when chorionic villi (CV) cytogenetic analysis is limited to a single placental layer; either a direct preparation (Dir) or long-term culture (LTC). METHODS: We retrospectively reviewed cytogenetic studies on 81,593 consecutive CV samples in which both Dir and LTC were analyzed. All mosaic cases received amniocentesis. The false omission and false discovery rates were calculated by assessing the results that would have been reported when analysis was limited to either Dir or LTC. RESULTS: For all abnormalities combined, the proportion of normal Dir or LTC only reports that would have been inconsistent with a subsequent amniocentesis was 0.09% and 0.03%, respectively (false omissions). Among abnormal reports based on Dir or LTC alone, 8.01% and 3.17%, respectively, would be inconsistent with a subsequent amniocentesis result (false discoveries). Differences are present for individual abnormalities. CONCLUSIONS: From the perspective of identifying all abnormalities of potential clinical significance, the analysis of both placental layers is optimal. LTC alone is the preferred approach if only one layer of placenta is to be analyzed. Although rare, it is important to acknowledge that one cell layer analysis alone can cause misdiagnosis due to undetected mosaicism.

Increased Fetal Chromosome Detection with the Use of Operative Hysteroscopy During Evacuation of Products of Conception for Diagnosed Miscarriage.

STUDY OBJECTIVE: To determine whether incorporation of operative hysteroscopy with biopsy of products of conception, in conjunction with a suction curettage for a first trimester missed abortion, affected the rate of maternal cell contamination when chromosomal analysis was performed on the products of conception, and to determine the rates of retained products of conception with incorporation of hysteroscopy after suction curettage. DESIGN: Retrospective chart study. SETTING: Private, minimally invasive surgery and infertility practice with academic-community hospital affiliation. PATIENTS: Infertility patients undergoing evacuation of products of conception for documented first trimester miscarriages between 2006 and 2017. INTERVENTIONS: Suction curettage or hysteroscopic biopsy and suction curettage, followed by chromosomal analysis of products of conception for determination of fetal genetics. MEASUREMENTS AND RESULTS: A total of 264 charts were analyzed. Patients were categorized into 2 groups based on surgical collection of products of conception: group 1 (N = 174), suction curettage only, and group 2 (N = 90), a single procedure consisting of operative hysteroscopy with biopsy of products of conception followed by suction curettage and then diagnostic hysteroscopy to look for retained products. Data for chromosome detection and retained products of conception were available for 246 and 239 patients, respectively. No significant differences were detected between the groups for age, body mass index, ethnicity, gravida, parity, primary infertility, secondary infertility, spontaneous conception, single or multiple gestation, and surgical complications. Fetal chromosome detection was significantly higher without maternal contamination in group 2 (88.5%) compared with group 1 (64.8%) (p < .001). There was no significant between-group difference in postoperative retained products of conception. CONCLUSION: Obtaining fetal genetics can be useful when planning for a future successful pregnancy. The addition of operative hysteroscopy to biopsy the gestational sac, chorionic villi, and/or fetus significantly decreases the risk of maternal contamination and increases the ability to detect fetal chromosomes for genetic analysis without an increased risk of surgical complications. Despite the low risk of surgical complications, immediate second-look hysteroscopy after the completion of suction evacuation does not reduce the risk of postoperative retained products of conception.

Should cell-free DNA testing be used in pregnancy with increased fetal nuchal translucency?

OBJECTIVE: To assess the frequency of atypical chromosomal and submicroscopic anomalies, as well as fetal structural abnormalities, observed on first-trimester ultrasound scan in fetuses with nuchal translucency (NT) thickness > 99th centile, in order to evaluate the suitability of using standard cell-free DNA (cfDNA) testing as the sole screening test in these pregnancies. METHODS: This was a retrospective cohort study of 226 fetuses with NT > 99th centile at 11-14 weeks' gestation, between January 2013 and December 2017, in a clinical setting in which greater than 95% of pregnant women receive first-trimester combined screening. All patients underwent genetic testing by means of quantitative fluorescence polymerase chain reaction and chromosomal microarray analysis, mainly in chorionic villus samples. We assessed the theoretical yield of two cfDNA testing models, targeted cfDNA (chromosomes 21, 18 and 13) and extended cfDNA (chromosomes 21, 18, 13 and sex chromosomes), and compared it with that of cytogenetic testing and ultrasound assessment in the first and second or third trimesters. RESULTS: In the 226 fetuses analyzed, cytogenetic testing revealed 84 (37%) anomalies, including 68 typical aneuploidies (involving chromosomes 13, 18 or 21), six sex chromosome aneuploidies (four cases of monosomy X and two of trisomy X), three clinically relevant atypical chromosomal anomalies (one trisomy 22, one trisomy 21 mosaicism and one unbalanced translocation), five submicroscopic pathogenic variants and two cases with Noonan syndrome. Targeted and extended cfDNA testing would miss at least 12% (10/84) and 19% (16/84), respectively, of genetic anomalies, accounting for 4.4% and 7.1% of the fetuses with an increased NT, respectively. Finally, of the 142 fetuses with no identified genetic anomaly, a major fetal malformation was observed in 15 (10.6%) fetuses at the early anomaly scan, and in 19 (13.4%) in the second or third trimester. CONCLUSIONS: cfDNA does not appear to be the appropriate genetic test in fetuses with NT > 99th centile, given that it would miss 12-19% of genetic anomalies in this group. Additionally, first-trimester ultrasound will identify a major structural abnormality in 11% of the fetuses with NT > 99th centile and no genetic anomaly. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Cytogenetic and molecular genetic characterization of KMT2A-PTD positive acute myeloid leukemia in comparison to KMT2A-Rearranged acute myeloid leukemia.

To define the biological differences in acute myeloid leukaemia (AML) with KMT2A gene involvements and their prognostic impact, we compared 190 de novo AML patients at diagnosis, 95 harbouring KMT2A-rearrangement (KMT2Ar) and 95 KMT2A-PTD by performing cytogenetic and molecular genetic analyses. Both AML subtypes had an unfavourable outcome, particularly in patients > 60 years. Patients with KMT2Ar were younger compared to patients with KMT2A-PTD (mean 52 vs 65 years, p < 0.001) and had a higher rate of additional cytogenetic abnormalities (ACA) (46% vs 25% of cases). In both groups, occurrence of ACA did not influence the overall survival (OS). Regarding molecular genetics, 66% of patients with KMT2Ar and 99% of patients with KMT2A-PTD had additional gene mutations. In multivariate analysis, KRAS mutations and 10p12 rearrangement resulted as adverse prognostic factors in KMT2Ar subgroup. In the KMT2A-PTD group, apart from age, only the occurrence of DNMT3A non-R882 mutations correlated with shorter OS.

The cytogenetic constitution of human blastocysts: insights from comprehensive chromosome screening strategies.

BACKGROUND: Embryos that are able to form blastocysts have succeeded in activating their genome and differentiating into two cell types-an external layer of trophectoderm cells, which will go on to form extra-embryonic tissues such as the placenta, and the inner cell mass, which will give rise to the embryo proper. Culturing embryos to the blastocyst stage has become an increasingly popular IVF practice over the past decade. Additionally, it has been proposed that the identification and transfer of euploid blastocysts could significantly improve IVF outcomes. Toward this end, comprehensive molecular cytogenetic methods have been developed. The application of such methods in both clinical and research contexts has yielded cytogenetic data from large numbers of blastocysts. Questions have been raised concerning the implantation potential of blastocysts diagnosed 'euploid' or 'aneuploid', and there has been particular debate over the detection and viability of embryos categorized as 'mosaic'-composed of a mixture of normal and aneuploid cells. OBJECTIVE AND RATIONALE: This review aims to summarize data from studies using comprehensive molecular cytogenetic methods to examine blastocyst-stage embryos, describing current knowledge related to rates of euploidy, uniform aneuploidy and mosaicism. Issues associated with the developmental capacity of blastocysts of different cytogenetic constitutions will also be addressed. Guidelines on the clinical management of blastocysts with varying chromosome complements will be considered. SEARCH METHODS: Rates of euploidy, uniform aneuploidy (in which all cells have the same abnormal karyotype) and mosaicism were determined via a thorough literature search (PubMed). The keywords used in the search were as follows: preimplantation embryo development, blastocyst stage, embryonic aneuploidy, meiotic chromosome malsegregation, post-zygotic chromosome malsegregation, comprehensive chromosome screening, array comparative genomic hybridization, single-nucleotide polymorphism array, next-generation sequencing, embryo mosaicism and implantation of mosaic embryos. Relevant articles written in English and published up to March 2018 were reviewed. OUTCOMES: Different types of aneuploidy, including some complex forms, are capable of persisting to the blastocyst stage. As expected, euploidy rates decreased with advancing female age, whereas uniform aneuploidy increased. Analysis of multiple cells from individual blastocysts revealed that most of those classified 'abnormal' contained no euploid cells (due to meiotic errors arising in the gametes and therefore present in every cell), some having additional mosaic (post-fertilization, mitotic) errors. Blastocysts with a mix of normal and aneuploid cells were observed less frequently than other classes of embryo. The transfer of embryos with diploid-aneuploid mosaic biopsy specimens is reportedly associated with higher miscarriage and lower implantation rates, compared to embryos in which only euploid cells are detected. WIDER IMPLICATIONS: Detailed investigations into the chromosome constitution of human blastocysts suggest that a significant proportion is euploid in every cell, although the exact fraction is strongly influenced by female age. These findings do not support the notion that mosaic chromosome abnormalities are a natural part of embryo development. Mosaic aneuploidies, arising post-zygotically, were detected by various different comprehensive molecular cytogenetic methods, suggesting that the majority of these represent genuine findings. However, it remains possible that certain comprehensive molecular cytogenetic methods may carry a risk of mosaicism being incorrectly assigned, in a minority of samples, as a result of technical artifact. This may be a consequence of degraded DNA in the trophectoderm biopsy or other technical issues. According to published studies, blastocysts considered to have uniform aneuploidy and, to a lesser extent, those with mosaic abnormalities were associated with poorer clinical outcomes in comparison with euploid embryos.

Treatment With JAK Inhibitors in Myelofibrosis Patients Nullifies the Prognostic Impact of Unfavorable Cytogenetics.

INTRODUCTION: In the era before Janus kinase (JAK) inhibitors, cytogenetic information was used to predict survival in myelofibrosis patients. However, the prognostic value of cytogenetics in the setting of JAK inhibitor therapy remains unknown. PATIENTS AND METHODS: We performed a retrospective analysis of 180 patients with bone marrow biopsy-proven myelofibrosis from 3 US academic medical centers. We fit Cox proportional hazards models for overall survival and transformation-free survival on the bases of 3 factors: JAK inhibitor therapy as a time-dependent covariate, dichotomized cytogenetic status (favorable vs. unfavorable), and statistical interaction between the two. The median follow-up time was 37.1 months. RESULTS: Among patients treated with best available therapy, unfavorable cytogenetic status was associated with decreased survival (hazard ratio = 2.31; P = .025). At initiation of JAK inhibitor therapy, unfavorable cytogenetics was (nonsignificantly) associated with increased survival compared to favorable cytogenetics (hazard ratio = 0.292; P = .172). The ratio of hazard ratios was 0.126 (P = .034). These findings were similar after adjusting for standard clinical prognostic factors as well as when measured against transformation-free survival. CONCLUSION: The initiation of JAK inhibitor therapy appears to change the association between cytogenetics and overall survival. There was little difference in survival between treatment types in patients with favorable cytogenetics. However, the use of JAK inhibitor therapy among patients with unfavorable cytogenetics was not associated with worse survival compared to favorable cytogenetics. Our analyses suggest that initiation of JAK inhibitor therapy nullifies the negative prognostic implication of unfavorable cytogenetics established in the pre-JAK inhibitor therapy era.

Prenatal diagnosis of Down syndrome: A 13-year retrospective study.

OBJECTIVE: The aim of this study is to summarize the experience on prenatal diagnosis of Down syndrome. MATERIALS AND METHODS: The study includes a retrospective data analysis of 157 prenatally detected cases of Down syndrome, routinely diagnosed among 6448 prenatal investigations performed during a 13-year period (2002-2014) in a single tertiary center. RESULTS: The prevalence of diagnosed Down syndrome cases was 2.4%. Maternal age alone was indication for prenatal diagnosis in 47 cases (45.2%), increased first-/second-trimester biochemical screening test in 34 cases (21.7%), abnormal ultrasound examination in 69 cases (43.9%), positive familial history for chromosomal abnormalities in four cases, and high risk for trisomy 21 revealed by cell-free DNA testing in three cases. Ultrasound anomalies were present in total of 94 fetuses (59.8%). The most common abnormality was cystic hygroma found in 46 cases (29.3%). A regular form of Down syndrome (trisomy 21) was found in 147 cases (93.6%), Robertsonian translocation in six cases (3.8%), and mosaic form in four cases (2.6%). CONCLUSION: In prenatal diagnosis of Down syndrome noninvasive screening methods are important for estimation of individual risks, in both, young population of woman and older mothers, while conventional and molecular cytogenetic methods are essential for definite diagnosis and proper genetic counseling.

[Hygienic environmental assessment in the oil-and-gas bearing area on the base of cytogenetical and molecular-genetic methods].

The study have been conducted in settlements located near oilfields of the Nizhnevartovsk area, the Khanty-Mansi autonomous district (Russian Federation). There were examined 802 persons aged of from 18 to 56 years not proximately employed in processes of the oil extraction. Control group was consisted of329 residents of the north of Tomsk Region living in the area without any polluting environment industry. By using such methods of analysis as micronucleus test in human buccal cells, the xenobiotic biotransformation of both GSTM1 and GSTT1 gene polymorphism, as well as the assessment of oil contamination of local drinking water there was executed the hygienic assessment of ecology in the settlements located near oil fields. The elevated rate of cytogenetic disorders was established to be observed most of all in the residents of this region, as well as in persons recently moved to this area. Most significant deviations from the control according to the micronucleus test were detected in individuals with the GSTM1 (0) /GSTT1(0) genotype. In the control group no such consistent pattern was seen.

Cytogenetic place in managing myelodysplastic syndromes: an update by the Groupe francophone de cytogénétique hématologique (GFCH).

The myelodysplastic syndromes (MDS) are preleukemic diseases of elderly patients characterized by defective maturation of clonal hematopoietic progenitor cells resulting in peripheral blood cytopenias. Clonal chromosomal abnormalities are heterogeneous and can be detected in less than 50% of patients with de novo MDS and more frequently in secondary MDS (up to 80%). The karyotype plays an important role in the pathogenesis, diagnosis, and prognosis to evaluate the risk of leukemic transformation and, more recently, in treatment allocation. The gold standard for cytogenetic diagnosis in MDS is conventional chromosome banding analyses of bone marrow metaphases. The most frequent abnormalities are deletions and losses of chromosomes 5 (-5/5q-) and 7 (-7/7q-) and various isolated or combined abnormalities. Fluorescent in situ hybridization and array comparative genomic hybridization can reveal cryptic genetic abnormalities but are not recommended in routine diagnosis. New techniques including next generation sequencing revealed somatic driver mutations especially those affecting genes involved in RNA splicing or those harboring important prognostic value (TP53, ASXL1…) with potential applications in clinical practice in the future.

Fenotipos neurológicos en pacientes estudiados con citogenética en el Hospital de Puerto Montt / Neurological phenotypes in cytogenic study from Puerto Montt Hospital patients

El examen citogenético, es una herramienta importante para confirmar el diagnóstico, manejo y consejo genético. El objetivo es analizar las características del fenotipo neuroconductual, protocolizar y orientar en la eficaz solicitud del estudio citogenético. Se revisaron las fichas clínicas de los pacientes controlados del policlínico de Neuropediatría del Hospital de Puerto Montt, con cariograma anormal entre los años 2007 y 2012. De 248 pacientes, 12% se identificó una alteración; 58% aberraciones estructurales, 20% aneuploidías, y 20% alteraciones genético - moleculares. Los elementos clínicos que se encontraron fueron microcefalia 48%, retraso mental 67%, historia familiar 67%, hipotonía 70%, convulsiones 41%, alteraciones del SNC 37%.

Cytogenetic examination is an important tool for confirming diagnosis, case management and genetic counseling. The aim is to analyze the characteristics of neurobehavioral phenotypes, formalize and guide the effective application of cytogenetics. The medical records of patients with abnormal karyotype seen between 2007 and 2012 at the Hospital of Puerto Montt's neuropaediatric outpatient clinic were reviewed. Of 248 patients, in 12% an alteration was identified; 58% structural aberrations, 20% aneuploidy, and 20% genetic-molecular alterations. The clinical elements found were 48% microcephaly, 67% mental retardation, 67% family history, 70% hypotonia, 41% seizures, 37% CNS disorders.

Emerging issues in invasive prenatal diagnosis: Safety and competency in the post-NIPT era.

BACKGROUND: Numbers of invasive prenatal procedures are declining in response to improved aneuploidy screening methods. OBJECTIVE: To assess current practice and attitudes of clinicians performing invasive prenatal diagnosis in regard to patient consent and safety, maintaining procedural competence and uptake of chromosomal microarrays (CMAs). METHODS: Anonymous online survey of the Australian Association of Obstetrical and Gynaecological Ultrasonologists conducted in March 2015. RESULTS: The survey had a 45% response rate with 59 respondents from Australia. Of these, 34 were subspecialists in maternal fetal medicine or obstetric and gynaecological ultrasound. Fifty-six (95%) currently performed amniocentesis or chorionic villus sampling. Of these, 14 (25%) performed <25 procedures and 8 (14%) performed >150 annually, with most respondents (60%) proposing 10-25 amniocenteses/year as adequate activity to maintain their skills. The majority neither expected referrers to provide results of hepatitis B and HIV serology, nor followed up missing results. There was uncertainty regarding the procedure-related vertical transmission risk of HBV in women with high viral load, with most respondents stating they were either unsure of the risk (22%) or that the risk was unknown (30%). Fifty per cent of practitioners routinely ordered CMA after invasive testing; all recommended CMA following a diagnosis of structural abnormality. CONCLUSIONS: In a period of declining testing, many Australian specialists are performing <25 procedures annually. Consideration of the potential risks of bloodborne viruses is limited. CMAs are rapidly being incorporated into clinical practice. These data have implications for patient consent and safety, and workforce training and practice.

Connect MM Registry: The Importance of Establishing Baseline Disease Characteristics.

BACKGROUND: Connect MM is the first and largest observational, noninterventional, prospective registry of patients newly diagnosed with multiple myeloma (NDMM) in the United States. It collects longitudinal data on patients within clinical practice including patients in clinical trials. PATIENTS AND METHODS: Of the 1513 patients enrolled, 1493 were protocol-eligible. RESULTS: Median age was 67 years, 81.9% (1223/1493) were Caucasian, and 57.2% (854/1493) were male. Of these patients, 26.5% (232/877) were International Staging System stage I, 34.9% (306/877) stage II, and 38.7% (339/877) stage III. Eastern Cooperative Oncology Group performance status of 0/1/2 were reported in 96.6% (1017/1053). Clonal plasma cells > 10% were found in 91.6% (1282/1399) of patients and M-component in 98.8% (1343/1359). Hypercalcemia was present in 7.3% (108/1481) of patients, serum creatinine > 2 mg/dL in 18.3% (271/1484), anemia in 45.1% (673/1493), and bone involvement in 76.7% (1143/1490). Of the 15 National Comprehensive Cancer Network (NCCN) recommended diagnostic tests, a median of 12 were performed. Lactate dehydrogenase assessment, serum free light chain ratio, and immunofixation were reported in 38.4% (574/1493), 62.1% (927/1493), and 66% (985/1493) of patients, respectively. Quantitative immunoglobulin, ß-2 microglobulin, and protein electrophoresis (serum or urine) were reported in 72.3% (1080/1493), 74.1% (1107/1493), and 78.0% (1164/1493) of patients, respectively. Bone marrow biopsy was reported in 92.2% (1376/1493), but conventional cytogenetic and fluorescence in situ hybridization analysis were reported in only 63.2% (944/1493) and 59.8% (893/1493) of patients, respectively. A high-risk cytogenetic profile (according to International Myeloma Working Group [IMWG] criteria) was found in 16.9% (253/1493). CONCLUSION: This analysis provides insight into the demographic and disease characteristics of NDMM patients in a range of clinical practices. Creating solid records of baseline patient disease characteristics using suggested NCCN diagnostic work-up and IMWG criteria provides a foundation for monitoring disease progression and response to treatment.

Current status of prenatal diagnosis in Cuba: causes of low prevalence of Down syndrome.

OBJECTIVES: To analyze trends in cytogenetic prenatal diagnosis in Cuba and to analyze possible causes leading to a low Down syndrome prevalence in a country where the triple test is not available. METHODS: An analysis of the Cuban program in prenatal cytogenetic diagnosis from 1984 to 2012 was conducted. Results are described, with particular emphasis on indications, abnormal results, types of invasive procedures, and terminations of pregnancy. RESULTS: Cytogenetic prenatal diagnostic analyses (n = 75,095) were conducted; maternal age was the indication for 77.9% of the amniocenteses and chorionic villus samplings. The detection rate of chromosomally abnormal pregnancies was 2.3% for maternal age and increased to 8-9% for other indications. When a chromosomal abnormality was identified, 88.5% terminated the pregnancy. In 2002, the live birth prevalence of Down syndrome was 8.4 per 10,000 live births, and in 2012, 7 per 10,000. CONCLUSION: Prenatal diagnosis in Cuba has contributed to a significant reduction in chromosomal aberrations. The impact increased because of the demographic trends of the population, the high index of terminations of pregnancy, and the establishment of a network of cytogenetic laboratories throughout Cuba.

Blastocyst biopsy with comprehensive chromosome screening and fresh embryo transfer significantly increases in vitro fertilization implantation and delivery rates: a randomized controlled trial.

OBJECTIVE: To determine whether blastocyst biopsy and rapid quantitative real-time polymerase chain reaction (qPCR)-based comprehensive chromosome screening (CCS) improves in vitro fertilization (IVF) implantation and delivery rates. DESIGN: Randomized controlled trial. SETTING: Academic reproductive medicine center. PATIENT(S): Infertile couples in whom the female partner (or oocyte donor) is between the ages of 21 and 42 years who are attempting conception through IVF. INTERVENTION(S): Embryonic aneuploidy screening. MAIN OUTCOME MEASURE(S): Sustained implantation and delivery rates. RESULT(S): We transferred 134 blastocysts to 72 patients in the study (CCS) group and 163 blastocysts to 83 patients in the routine care (control) group. Sustained implantation rates (probability that an embryo will implant and progress to delivery) were statistically significantly higher in the CCS group (89 of 134; 66.4%) compared with those from the control group (78 of 163; 47.9%). Delivery rates per cycle were also statistically significantly higher in the CCS group. Sixty one of 72 treatment cycles using CCS led to delivery (84.7%), and 56 of 83 (67.5%) control cycles ultimately delivered. Outcomes were excellent in both groups, but use of CCS clearly improved patient outcomes. CONCLUSION(S): Blastocyst biopsy with rapid qPCR-based comprehensive chromosomal screening results in statistically significantly improved IVF outcomes, as evidenced by meaningful increases in sustained implantation and delivery rates. CLINICAL TRIAL REGISTRATION NUMBER: NCT01219283.

Chromosome analysis of nuclear power plant workers using fluorescence in situ hybridization and Giemsa assay.

The aim of this study was to evaluate the genotoxic effects of ionizing radiation in vivo in exposed Bulgarian nuclear power plant workers by using classical cytogenetic and molecular cytogenetic analyses of peripheral lymphocytes. Chromosome analysis using fluorescence in situ hybrydization (FISH) and Giemsa techniques was undertaken on 63 workers and 45 administrative staff controls from the Bulgarian Nuclear Power Plant. Using the Giemsa method, the frequencies of cells studied with chromosome aberrations, dicentrics plus rings and chromosome fragments in the radiation workers were significantly higher compared with the control group (P = 0.044, P = 0.014, and P = 0.033, respectively). A significant association between frequencies of dicentrics plus rings and accumulated doses was registered (P < 0.01). In the present study, a FISH cocktail of whole chromosome paints for chromosomes 1, 4 and 11 was used. A significant association between frequency of translocations and accumulated doses was also observed (P < 0.001). Within the control group, a correlation was found between age and the spontaneous frequency of translocations. No correlation was found between smoking status and frequency of translocations. When compared with the control group, workers with accumulated doses up to 100 mSv showed no increase in genome translocation frequency, whereas workers with accumulated doses from 101 to 200 mSv showed a statistically significant doubling of genome translocation frequency (P = 0.009). Thus, in cases of chronic exposure and for purposes of retrospective dosimetry, the genome frequency of translocations is a more useful marker for evaluation of genotoxic effects than dicentric frequency.

Impact of introducing a national policy for prenatal Down syndrome screening on the diagnostic invasive procedure rate in England.

OBJECTIVE: To evaluate the impact of the introduction of a Down syndrome screening policy in England, including implementation of the first-trimester combined screening test, on reducing prenatal invasive diagnostic procedure rates. METHODS: All English cytogenetic laboratories were asked to submit data from the fiscal years 2003/2004 until 2011/2012 on all samples received from prenatal invasive procedures, including those that were undertaken following a higher-risk Down syndrome screening result. RESULTS: There was a gradual decline in the number of invasive procedures undertaken subsequent to a positive Down syndrome screening result in England, from 36 968 in 2003/2004 to 11 446 in 2008/2009, with only a relatively small subsequent decrease, to 10 215, in 2011/2012. This corresponds to a 72% reduction in the number of referrals received by the cytogenetic laboratories over a 9-year period and correlates with the national policy of implementing the combined screening test in place of second-trimester screening, which has reduced the overall screen-positive rate to 3.1% from an initial level of 6.0%. CONCLUSIONS: Implementation of a national Down syndrome screening policy based on the combined screening test has significantly reduced the number of invasive tests performed. However, as the combined screening test has become the replacement for second-trimester testing and has been almost completely implemented it appears that improvements in screening using current approaches may have reached their limits.

Clinical utilization of high-resolution single nucleotide polymorphism based oligonucleotide arrays in diagnostic studies of pediatric patients with solid tumors.

High-resolution single nucleotide polymorphism (SNP) arrays have been effectively implemented as a first tier test in clinical cytogenetics laboratories for the detection of constitutional chromosomal abnormalities in patients with suspected genomic disorders. We recently published our experience utilizing SNP array analysis of bone marrow aspirates as a clinical test for patients with suspected leukemia or lymphoma in the Clinical Cancer Cytogenetics Laboratory at The Children's Hospital of Philadelphia. In the present report we summarize our clinical experience using the Illumina HumanHap610 BeadChip array (Illumina, San Diego, CA) for whole genome analysis of pediatric solid tumors. A total of 168 DNA samples isolated from a variety of solid tumors, including brain tumors, sarcomas, neuroblastomas, and Wilms tumors, as well as benign neoplasms and reactive processes, were analyzed over a 2 1/2 year period. One hundred thirty-seven of 168 (82%) specimens had at least one copy number alteration or region of loss of heterozygosity detected by the SNP array. Thirty-three of 168 (20%) of cases had a normal karyotype or targeted fluorescence in situ hybridization (FISH) study, but had an abnormal finding by the array analysis. Sixty-three of 168 (37%) samples for which cytogenetic studies were unsuccessful or not performed demonstrated an abnormal array result. In 44 of 168 cases (26%) the array and karyotype or FISH were abnormal, but each demonstrated alterations not detected by the other methodology. Based on our experience in the last 2 1/2 years, we suggest that SNP array analysis can be used as a first tier clinical test for the majority of pediatric solid tumors.

Sister chromatid exchange (SCE) and high-frequency cells (HFC) in peripheral blood lymphocytes of healthy Tunisian smokers.

Cigarette smoking is a major public health problem in Tunisia as it concerns up to 30-35% of the adult population, raising important national issues on tobacco-related disease. The aim of this study was to establish whether cigarette smoking increases sister chromatid exchange (SCE) in peripheral blood lymphocytes of smokers (n=14) compared with non-smokers (n=15) in Sfax, Tunisia. The smokers were subdivided in two subgroups according to the duration of the smoking habit: heavy smokers (>10 years) and light smokers (≤10 years). After signing a consent form, volunteers provided a blood sample (5ml) to establish cell cultures during 72h. For SCE analysis, 30 second-division metaphases were examined from each subject. We determined the frequency of SCE, the percentage of high-frequency cells (HFC) and that of the high-frequency cell individual (HFI). The results show a significantly higher SCE frequency in smokers (8.65±1.43) than in non-smokers (7.16±1.3; p<0.01). A significant difference in SCE frequency was also shown when comparing the two subgroups of smokers (p<0.05). Interestingly, no significant difference was found when comparing the light smokers with non-smokers (7.82±1 vs 7.16±1.3, respectively, p>0.05). The percentages of HFC and HFI were significantly higher in smokers (11.2±7.8% and 78.6%, respectively) than in non-smokers (4±2.2% and 20%, respectively, p<0.01). Our study indicates that the genotoxic effects in lymphocytes from healthy Tunisian smokers are most likely caused by cigarette-smoke constituents. This effect was mainly observed in smokers who had been smoking during more than 10 years. These results provide scientific evidence to urge the prevention of tobacco consumption.

Weighted clustering of called array CGH data.

Array comparative genomic hybridization (aCGH) is a laboratory technique to measure chromosomal copy number changes. A clear biological interpretation of the measurements is obtained by mapping these onto an ordinal scale with categories loss/normal/gain of a copy. The pattern of gains and losses harbors a level of tumor specificity. Here, we present WECCA (weighted clustering of called aCGH data), a method for weighted clustering of samples on the basis of the ordinal aCGH data. Two similarities to be used in the clustering and particularly suited for ordinal data are proposed, which are generalized to deal with weighted observations. In addition, a new form of linkage, especially suited for ordinal data, is introduced. In a simulation study, we show that the proposed cluster method is competitive to clustering using the continuous data. We illustrate WECCA using an application to a breast cancer data set, where WECCA finds a clustering that relates better with survival than the original one.