Immortalization of normal human mammary epithelial cells in two steps by direct targeting of senescence barriers does not require gross genomic alterations.

Telomerase reactivation and immortalization are critical for human carcinoma progression. However, little is known about the mechanisms controlling this crucial step, due in part to the paucity of experimentally tractable model systems that can examine human epithelial cell immortalization as it might occur in vivo. We achieved efficient non-clonal immortalization of normal human mammary epithelial cells (HMEC) by directly targeting the 2 main senescence barriers encountered by cultured HMEC. The stress-associated stasis barrier was bypassed using shRNA to p16(INK4); replicative senescence due to critically shortened telomeres was bypassed in post-stasis HMEC by c-MYC transduction. Thus, 2 pathologically relevant oncogenic agents are sufficient to immortally transform normal HMEC. The resultant non-clonal immortalized lines exhibited normal karyotypes. Most human carcinomas contain genomically unstable cells, with widespread instability first observed in vivo in pre-malignant stages; in vitro, instability is seen as finite cells with critically shortened telomeres approach replicative senescence. Our results support our hypotheses that: (1) telomere-dysfunction induced genomic instability in pre-malignant finite cells may generate the errors required for telomerase reactivation and immortalization, as well as many additional "passenger" errors carried forward into resulting carcinomas; (2) genomic instability during cancer progression is needed to generate errors that overcome tumor suppressive barriers, but not required per se; bypassing the senescence barriers by direct targeting eliminated a need for genomic errors to generate immortalization. Achieving efficient HMEC immortalization, in the absence of "passenger" genomic errors, should facilitate examination of telomerase regulation during human carcinoma progression, and exploration of agents that could prevent immortalization.

Genome-wide analysis reveals the unique stem cell identity of human amniocytes.

Human amniotic fluid contains cells that potentially have important stem cell characteristics, yet the programs controlling their developmental potency are unclear. Here, we provide evidence that amniocytes derived from multiple patients are marked by heterogeneity and variability in expression levels of pluripotency markers. Clonal analysis from multiple patients indicates that amniocytes have large pools of self-renewing cells that have an inherent property to give rise to a distinct amniocyte phenotype with a heterogeneity of pluripotent markers. Significant to their therapeutic potential, genome-wide profiles are distinct at different gestational ages and times in culture, but do not differ between genders. Based on hierarchical clustering and differential expression analyses of the entire transcriptome, amniocytes express canonical regulators associated with pluripotency and stem cell repression. Their profiles are distinct from human embryonic stem cells (ESCs), induced-pluripotent stem cells (iPSCs), and newborn foreskin fibroblasts. Amniocytes have a complex molecular signature, coexpressing trophoblastic, ectodermal, mesodermal, and endodermal cell-type-specific regulators. In contrast to the current view of the ground state of stem cells, ESCs and iPSCs also express high levels of a wide range of cell-type-specific regulators. The coexpression of multilineage differentiation markers combined with the strong expression of a subset of ES cell repressors in amniocytes suggests that these cells have a distinct phenotype that is unlike any other known cell-type or lineage.

Rapid aneusomy detection in products of conception using the KaryoLite™ BACs-on-Beads™ assay.

OBJECTIVE: Chromosome analysis is the traditional method for detecting genetic abnormalities in products of conception, but it is prone to a high failure rate because of the requirement for cell culture. Molecular genetic tests do not require cell culture, but are either more expensive (e.g. chromosomal microarray) or less sensitive than chromosome analysis (e.g. fluorescence in situ hybridization, multiplex ligation mediated amplification). The KaryoLite™ BACs-on-Beads™ (KL-BoBs™) assay is highly multiplexed with low resolution coverage and is designed to detect aneusomy for any chromosome. METHODS: We retrospectively tested 100 products of conception samples previously characterized by karyotype (n = 90), and/or microarray (n = 61) using KL-BoBs™. We included samples extracted from either cultured or direct specimens from placental villi or fetal somatic tissue, with a variety of chromosomal abnormalities typically identified in our clinical cytogenetics laboratory. RESULTS: KL-BoBs™ and microarray results were concordant for all cases of aneusomy. On the basis of a review of 3794 consecutive cases in our laboratory, aneusomy accounts for 74.3% of abnormalities detected. Polyploidy and structural abnormalities were not detected by KL-BoBs™. CONCLUSION: KL-BoBs™ is potentially very useful as a first line test for aneusomy detection because of its lower cost, rapid detection, and ability to generate a molecular karyotype for samples that fail to grow in culture.

Polyostotic fibrous dysplasia in a cynomolgus Macaque (Macaca fascicularis).

A 2.3-y-old female cynomolgus macaque (Macaca fascicularis) presented with a broken right tibia and fibula. Radiographs showed multiple cyst-like defects in all long bones. We suspected that both fractures were pathologic because they occurred through these defects. Ultrasonography, MRI, and dual X-ray absorptiometry revealed that the defects were filled with soft tissue. Grossly, the bones were abnormal in shape, and a gelatinous material filled the defects and the surrounding marrow cavity. Histologically, the gelatinous material was composed of fibrin and cartilage; few normal bone cells were seen. Genetic testing revealed extra material on the short arm of chromosome 8 in all tissues examined, but no copy number alterations of likely clinical significance were observed, and no abnormalities were found that were unique to the lesions. In light of the clinical signs and radiographic and pathologic findings, polyostotic fibrous dysplasia was diagnosed. This report represents the first documented case of fibrous dysplasia in a cynomolgus macaque.

An evidence-based approach to establish the functional and clinical significance of copy number variants in intellectual and developmental disabilities.

PURPOSE: Copy number variants have emerged as a major cause of human disease such as autism and intellectual disabilities. Because copy number variants are common in normal individuals, determining the functional and clinical significance of rare copy number variants in patients remains challenging. The adoption of whole-genome chromosomal microarray analysis as a first-tier diagnostic test for individuals with unexplained developmental disabilities provides a unique opportunity to obtain large copy number variant datasets generated through routine patient care. METHODS: A consortium of diagnostic laboratories was established (the International Standards for Cytogenomic Arrays consortium) to share copy number variant and phenotypic data in a central, public database. We present the largest copy number variant case-control study to date comprising 15,749 International Standards for Cytogenomic Arrays cases and 10,118 published controls, focusing our initial analysis on recurrent deletions and duplications involving 14 copy number variant regions. RESULTS: Compared with controls, 14 deletions and seven duplications were significantly overrepresented in cases, providing a clinical diagnosis as pathogenic. CONCLUSION: Given the rapid expansion of clinical chromosomal microarray analysis testing, very large datasets will be available to determine the functional significance of increasingly rare copy number variants. This data will provide an evidence-based guide to clinicians across many disciplines involved in the diagnosis, management, and care of these patients and their families.

College of American Pathologists/American College of Medical Genetics proficiency testing for constitutional cytogenomic microarray analysis.

PURPOSE: To evaluate the feasibility of administering a newly established proficiency test offered through the College of American Pathologists and the American College of Medical Genetics for genomic copy number assessment by microarray analysis, and to determine the reproducibility and concordance among laboratory results from this test. METHODS: Surveys were designed through the Cytogenetic Resource Committee of the two colleges to assess the ability of testing laboratories to process DNA samples provided and interpret results. Supplemental questions were asked with each Survey to determine laboratory practice trends. RESULTS: Twelve DNA specimens, representing 2 pilot and 10 Survey challenges, were distributed to as many as 74 different laboratories, yielding 493 individual responses. The mean consensus for matching result interpretations was 95.7%. Responses to supplemental questions indicate that the number of laboratories offering this testing is increasing, methods for analysis and evaluation are becoming standardized, and array platforms used are increasing in probe density. CONCLUSION: The College of American Pathologists/American College of Medical Genetics proficiency testing program for copy number assessment by cytogenomic microarray is a successful and efficient mechanism for assessing interlaboratory reproducibility. This will provide laboratories the opportunity to evaluate their performance and assure overall accuracy of patient results. The high level of concordance in laboratory responses across all testing platforms by multiple facilities highlights the robustness of this technology.

Craniorachischisis and omphalocele in a stillborn cynomolgus monkey (Macaca fascicularis).

Nonhuman primates have been a common animal model to evaluate experimentally induced malformations. Reports on spontaneous malformations are important in determining the background incidence of congenital anomalies in specific species and in evaluating experimental results. Here we report on a stillborn cynomolgus monkey (Macaca fascicularis) with multiple congenital anomalies from the colony maintained at the Southwest National Primate Research Center at the Texas Biomedical Research Institute, San Antonio, Texas. Physical findings included low birth weight, craniorachischisis, facial abnormalities, omphalocele, malrotation of the gut with areas of atresia and intussusception, a Meckel diverticulum, arthrogryposis, patent ductus arteriosus, and patent foramen ovale. The macaque had normal male external genitalia, but undescended testes. Gestational age was unknown but was estimated from measurements of the limbs and other developmental criteria. Although cytogenetic analysis was not possible due to the tissues being in an advanced state of decomposition, array Comparative Genomic Hybridization analysis using human bacterial artificial chromosome clones was successful in effectively eliminating aneuploidy or any copy number changes greater than approximately 3-5 Mb as a cause of the malformations. Further evaluation of the animal included extensive imaging of the skeletal and neural tissue defects. The animal's congenital anomalies are discussed in relation to the current hypotheses attempting to explain the frequent association of neural tube defects with other abnormalities.

Cytogenomic aberrations associated with prostate cancer.

Genetic changes associated with prostate cancer have finally begun to elucidate some of the mechanisms involved in the etiology of this complex and common disease. We highlight consistent and relatively frequent abnormalities seen by various methodologies. Specifically, the results of conventional and molecular cytogenetic studies, genome-wide association studies with single nucleotide polymorphisms, recurrent gene fusions, and epigenetic analyses are discussed.

Prognostic value of an RNA expression signature derived from cell cycle proliferation genes in patients with prostate cancer: a retrospective study.

BACKGROUND: Optimum management of clinically localised prostate cancer presents unique challenges because of the highly variable and often indolent natural history of the disease. To predict disease aggressiveness, clinicians combine clinical variables to create prognostic models, but the models have limited accuracy. We assessed the prognostic value of a predefined cell cycle progression (CCP) score in two cohorts of patients with prostate cancer. METHODS: We measured the expression of 31 genes involved in CCP with quantitative RT-PCR on RNA extracted from formalin-fixed paraffin-embedded tumour samples, and created a predefined score and assessed its usefulness in the prediction of disease outcome. The signature was assessed retrospectively in a cohort of patients from the USA who had undergone radical prostatectomy, and in a cohort of randomly selected men with clinically localised prostate cancer diagnosed by use of a transurethral resection of the prostate (TURP) in the UK who were managed conservatively. The primary endpoint was time to biochemical recurrence for the cohort of patients who had radical prostatectomy, and time to death from prostate cancer for the TURP cohort. FINDINGS: After prostatectomy, the CCP score was useful for predicting biochemical recurrence in the univariate analysis (hazard ratio for a 1-unit change [doubling] in CCP 1·89; 95% CI 1·54-2·31; p=5·6×10(-9)) and the best multivariate analysis (1·77, 1·40-2·22; p=4·3×10(-6)). In the best predictive model (final multivariate analysis), the CCP score and prostate-specific antigen (PSA) concentration were the most important variables and were more significant than any other clinical variable. In the TURP cohort, the CCP score was the most important variable for prediction of time to death from prostate cancer in both univariate analysis (2·92, 2·38-3·57, p=6·1×10(-22)) and the final multivariate analysis (2·57, 1·93-3·43; p=8·2×10(-11)), and was stronger than all other prognostic factors, although PSA concentration also added useful information. Heterogeneity in the hazard ratio for the CCP score was not noted in any case for any clinical variables. INTERPRETATION: The results of this study provide strong evidence that the CCP score is a robust prognostic marker, which, after additional validation, could have an essential role in determining the appropriate treatment for patients with prostate cancer. FUNDING: Cancer Research UK, Queen Mary University of London, Orchid Appeal, US National Institutes of Health, and Koch Foundation.

Deletion 17q12 is a recurrent copy number variant that confers high risk of autism and schizophrenia.

Autism spectrum disorders (ASD) and schizophrenia are neurodevelopmental disorders for which recent evidence indicates an important etiologic role for rare copy number variants (CNVs) and suggests common genetic mechanisms. We performed cytogenomic array analysis in a discovery sample of patients with neurodevelopmental disorders referred for clinical testing. We detected a recurrent 1.4 Mb deletion at 17q12, which harbors HNF1B, the gene responsible for renal cysts and diabetes syndrome (RCAD), in 18/15,749 patients, including several with ASD, but 0/4,519 controls. We identified additional shared phenotypic features among nine patients available for clinical assessment, including macrocephaly, characteristic facial features, renal anomalies, and neurocognitive impairments. In a large follow-up sample, the same deletion was identified in 2/1,182 ASD/neurocognitive impairment and in 4/6,340 schizophrenia patients, but in 0/47,929 controls (corrected p = 7.37 × 10⁻5). These data demonstrate that deletion 17q12 is a recurrent, pathogenic CNV that confers a very high risk for ASD and schizophrenia and show that one or more of the 15 genes in the deleted interval is dosage sensitive and essential for normal brain development and function. In addition, the phenotypic features of patients with this CNV are consistent with a contiguous gene syndrome that extends beyond RCAD, which is caused by HNF1B mutations only.

Consensus statement: chromosomal microarray is a first-tier clinical diagnostic test for individuals with developmental disabilities or congenital anomalies.

Chromosomal microarray (CMA) is increasingly utilized for genetic testing of individuals with unexplained developmental delay/intellectual disability (DD/ID), autism spectrum disorders (ASD), or multiple congenital anomalies (MCA). Performing CMA and G-banded karyotyping on every patient substantially increases the total cost of genetic testing. The International Standard Cytogenomic Array (ISCA) Consortium held two international workshops and conducted a literature review of 33 studies, including 21,698 patients tested by CMA. We provide an evidence-based summary of clinical cytogenetic testing comparing CMA to G-banded karyotyping with respect to technical advantages and limitations, diagnostic yield for various types of chromosomal aberrations, and issues that affect test interpretation. CMA offers a much higher diagnostic yield (15%-20%) for genetic testing of individuals with unexplained DD/ID, ASD, or MCA than a G-banded karyotype ( approximately 3%, excluding Down syndrome and other recognizable chromosomal syndromes), primarily because of its higher sensitivity for submicroscopic deletions and duplications. Truly balanced rearrangements and low-level mosaicism are generally not detectable by arrays, but these are relatively infrequent causes of abnormal phenotypes in this population (<1%). Available evidence strongly supports the use of CMA in place of G-banded karyotyping as the first-tier cytogenetic diagnostic test for patients with DD/ID, ASD, or MCA. G-banded karyotype analysis should be reserved for patients with obvious chromosomal syndromes (e.g., Down syndrome), a family history of chromosomal rearrangement, or a history of multiple miscarriages.

Variability in interpreting and reporting copy number changes detected by array-based technology in clinical laboratories.

PURPOSE: : The purpose of this study was to assess the variability in interpretation and reporting of copy number changes that are detected by array-based technology in the clinical laboratory. METHODS: : Thirteen different copy number changes, detected by array comparative genomic hybridization, that have not been associated with an abnormal phenotype in the literature were evaluated by directors from 11 different clinical laboratories to determine how they would interpret and report the findings. RESULTS: : For none of the thirteen copy number changes was there complete agreement in the interpretation of the clinical significance of the deletion or duplication. For some cases, the interpretations ranged from normal to abnormal. CONCLUSION: : There is a need for more specific guidelines for interpreting and reporting copy number changes detected by array-based technology to clearly and more consistently communicate the clinical significance of these findings to ordering providers.

Array comparative genomic hybridization for genetic evaluation of fetal loss between 10 and 20 weeks of gestation.

OBJECTIVE: To estimate genomic copy number changes in fetal loss between 10 and 20 weeks of gestation using array comparative genomic hybridization. METHODS: This was a prospective series of 35 women who experienced pregnancy loss between 10-20 weeks of gestation with either normal karyotype (n=9) or no conventional cytogenetic testing (n=26). DNA was isolated from fetal tissue and parental blood. Array comparative genomic hybridization was performed on DNA from fetal tissue using a whole genome BAC array chip. Copy number changes in fetal tissue were then compared against databases of benign copy number changes. Parental DNA was analyzed using the same BAC array in cases that contained suspected pathogenic copy number changes. In cases where de novo copy number changes were detected in fetal DNA, further characterization was performed using a 244K oligonucleotide microarray. RESULTS: DNA was successfully isolated in 30 of 35 (86%) of cases. Array comparative genomic hybridization was performed in all of these. De novo copy number changes were detected in six (20%) cases using the Spectral chip and confirmed in four (13%) cases using the Agilent chip. These ranged in size from 93-289 Kb and mapped on 5p, 13q and Xq22. In the cases with de novo copy number changes, the higher-density Agilent array detected additional changes (20-1,310 Kb). CONCLUSION: Array comparative genomic hybridization detected de novo copy number changes in 13% of cases where routine cytogenetic testing was normal or not performed. These involved large regions of DNA and may provide novel explanations for some cases of otherwise unexplained pregnancy loss. LEVEL OF EVIDENCE: III.

Evaluation of LOINC for representing constitutional cytogenetic test result reports.

Genetic testing is becoming increasingly important to medical practice. Integrating genetics and genomics data into electronic medical records is crucial in translating genetic discoveries into improved patient care. Information technology, especially Clinical Decision Support Systems, holds great potential to help clinical professionals take full advantage of genomic advances in their daily medical practice. However, issues relating to standard terminology and information models for exchanging genetic testing results remain relatively unexplored. This study evaluates whether the current LOINC standard is adequate to represent constitutional cytogenetic test result reports using sample result reports from ARUP Laboratories. The results demonstrate that current standard terminology is insufficient to support the needs of coding cytogenetic test results. The terminology infrastructure must be developed before clinical information systems will be able to handle the high volumes of genetic data expected in the near future.

Co-occurrence of 4p16.3 deletions with both paternal and maternal duplications of 11p15: modification of the Wolf-Hirschhorn syndrome phenotype by genetic alterations predicted to result in either a Beckwith-Wiedemann or Russell-Silver phenotype.

Paternal duplications of chromosome region 11p15 can result in Beckwith-Weidemann syndrome (BWS), whereas maternal duplications of the same region on 11p15 can result in Russell-Silver syndrome (RSS). These two syndromes have numerous opposing phenotypes, especially with regards to growth parameters. The differences in the phenotype are proposed to be due to altered dosage of imprinted genes that control growth within this region of 11p15. Wolf-Hirschhorn syndrome (WHS) is due to deletions of a region in 4p16.3 and there is no known parent-of-origin effect for deletions of the WHS critical region, and no genes are known to be imprinted in this region. We report on three individuals with very similar unbalanced translocations resulting in a derivative chromosome 4 with both a deletion of 4p16.3 and a duplication of 11p15. Two of these individuals are family members with one inheriting the derivative 4 from her balanced mother and the other inheriting the derivative 4 from his balanced father. The third individual is unrelated and inherited his derivative 4 from his balanced father. While the findings of these individuals included some features of WHS and RSS or BWS, the phenotypes as an aggregate are distinct from these syndromes. The genomic and phenotypic characterization of these three individuals demonstrates how unbalanced translocations can result in the modification of chromosome duplication and deletion syndromes and identifies genomic architecture that may be responsible for mediating a recurrent translocation between 4p and 11p.

Homozygous deletions of a copy number change detected by array CGH: a new cause for mental retardation?

We describe two unrelated patients with mental retardation and normal karyotypes found to have relatively large homozygous deletions (>150 kb) of different regions detected by array comparative genomic hybridization (aCGH). Patient 1 showed a 157-214 kb deletion at 8q24.2, containing BAC clone RP11-17M8. This patient was born to phenotypically normal parents and has microcephaly, distinctive craniofacial features, brachymetacarpia, brachymetatarsia and severe mental retardation. This BAC clone is listed as a copy number variant on the Database of Genomic Variants (http://projects.tcag.ca/variation/). Heterozygosity for the deletion was found in the mother (father is deceased) and uniparental disomy of chromosome 8 was excluded. Patient 2 showed a 812-902 kb deletion at 12q21.1, containing BAC clone RP11-89P15. This region was not listed in any public database as a known variant. This patient has mild craniofacial dysmorphic features, bifid uvula, peripheral pulmonic stenosis and developmental delay. Heterozygosity for this deletion was confirmed in the phenotypically normal parents and two normal siblings, but surprisingly, homozygosity for the deletion in an apparently normal younger sibling brings into question whether this large homozygous copy number change (CNC) is causal. Homozygous deletions of CNCs have not previously been reported in association with a phenotype or mental retardation. These cases represent homozygosity for presumably benign CNCs, and while causality for the phenotypes cannot be confirmed, similar deletions are bound to be identified more frequently as aCGH is used with increasing regularity. Such homozygous deletions should be viewed as potentially clinically relevant.

How physicians use array comparative genomic hybridization results to guide patient management in children with developmental delay.

PURPOSE: Array comparative genomic hybridization is an emerging test used clinically to identify the etiology of children with developmental delay, yet little data are available regarding how physicians use these results. This pilot study evaluated how positive test results were used to influence patient management. METHODS: We surveyed 14 physicians of 48 patients who had copy number changes detected by microarray technology. RESULTS: Of 48 patients, 34 (70.8%) had 65 management changes after receiving the test result (with individual patients having 1-3 changes). Most commonly, physicians provided patients' families with a recurrence risk for affected subsequent pregnancies (35% of patients). Patients avoided other forms of testing (35%) and had improved access to services (25%). In 27% of patients, physicians altered medical management by referring patients to a specialist or recommending medical screening. Patients with known syndromes had multiple changes, but patients with novel copy number changes also had recommendations made based on the array result. CONCLUSIONS: Overall, physicians reported making changes in management among most patients with positive test results, in ways similar to abnormalities detected by conventional cytogenetics. Our study demonstrates that this testing, in our clinical setting, is affecting management of children with developmental delay.

Genomic medicine in prenatal diagnosis.

Prenatal diagnostics has seen a rapid increase in the number of genetic disorders amenable to prenatal detection owing to advances in technology and research into the genetic etiology of many conditions. This article reviews the more traditional prenatal diagnostic techniques, such as amniocentesis and chorionic villus sampling for chromosome abnormalities and single gene disorders, and chromosome analysis of products of conception to determine the etiology of a spontaneous abortion, plus more recent advances such as rapid aneuploidy detection via fluorescence in situ hybridization and polymerase chain reaction, preimplantation genetic diagnosis, noninvasive analysis of cell-free fetal DNA in maternal circulation, and array-based comparative genomic hybridization.

Comprehensive analysis of Wolf-Hirschhorn syndrome using array CGH indicates a high prevalence of translocations.

Wolf-Hirschhorn syndrome (WHS) is caused by deletions involving chromosome region 4p16.3. The minimal diagnostic criteria include mild-to-severe mental retardation, hypotonia, growth delay and a distinctive facial appearance. Variable manifestations include feeding difficulties, seizures and major congenital anomalies. Clinical variation may be explained by variation in the size of the deletion. However, in addition to having a deletion involving 4p16.3, previous studies indicate that approximately 15% of WHS patients are also duplicated for another chromosome region due to an unbalanced translocation. It is likely that the prevalence of unbalanced translocations resulting in WHS is underestimated since they can be missed using conventional chromosome analyses such as karyotyping and WHS-specific fluorescence in situ hybridization (FISH). Therefore, we hypothesized that some of the clinical variation may be due to an unrecognized and unbalanced translocation. Array comparative genomic hybridization (aCGH) is a new technology that can analyze the entire genome at a significantly higher resolution over conventional cytogenetics to characterize unbalanced rearrangements. We used aCGH to analyze 33 patients with WHS and found a much higher than expected frequency of unbalanced translocations (15/33, 45%). Seven of these 15 cases were cryptic translocations not detected by a previous karyotype combined with WHS-specific FISH. Three of these 15 cases had an unbalanced translocation involving the short arm of an acrocentric chromosome and were not detected by either aCGH or subtelomere FISH. Analysis of clinical manifestations of each patient also revealed that patients with an unbalanced translocation often presented with exceptions to some expected phenotypes.