ABSTRACT
Projections of precipitation extremes in simulations with global climate models are very uncertain in the tropics, in part because of the use of parameterizations of deep convection and model deficiencies in simulating convective organization. Here, we analyse precipitation extremes in high-resolution simulations that are run without a convective parameterization on a quasi-global aquaplanet. The frequency distributions of precipitation rates and precipitation cluster sizes in the tropics of a control simulation are similar to the observed distributions. In response to climate warming, 3 h precipitation extremes increase at rates of up to [Formula: see text] in the tropics because of a combination of positive thermodynamic and dynamic contributions. The dynamic contribution at different latitudes is connected to the vertical structure of warming using a moist static stability. When the precipitation rates are first averaged to a daily timescale and coarse-grained to a typical global climate-model resolution prior to calculating the precipitation extremes, the response of the precipitation extremes to warming becomes more similar to what was found previously in coarse-resolution aquaplanet studies. However, the simulations studied here do not exhibit the high rates of increase of tropical precipitation extremes found in projections with some global climate models. This article is part of a discussion meeting issue 'Intensification of short-duration rainfall extremes and implications for flash flood risks'.
ABSTRACT
Our objective was to model process variation of Emergency Medical Service teams responding to simulated pediatric emergencies and determine if sequence alignment distinguishes performance quality. We performed a retrospective process analysis by watching and coding activities in videos from standardized simulations of 42 Emergency Medical Service teams. Teams were classified into high- or low-performing groups based on the Clinical Teamwork Scale™. Activities were coded according to resuscitation tasks, performer, and times. We used ClustalG to align task sequences within and between groups, and measured similarity. Teams within and between performance levels had an average sequence similarity of 52 ± 7% and 50 ± 7%. Teams performed clinically appropriate tasks that varied in prioritization, for example, performing compressions or connecting the EKG monitor early. There was no statistical difference in gross similarity between groups but specific differences in prioritization may have had clinically meaningful implications. Alignment could improve by accounting for task duration and concurrency.
ABSTRACT
Triple negative breast cancer (TNBC) is an aggressive subtype with relatively poor clinical outcomes and limited treatment options. Chemotherapy, while killing cancer cells, can result in the generation of highly chemoresistant therapeutic induced senescent (TIS) cells that potentially form stem cell niches resulting in metastases. Intriguingly, senescent cells release significantly more extracellular vesicles (EVs) than non-senescent cells. Our aim was to profile EVs harvested from TIS TNBC cells compared with control cells to identify a potential mechanism by which TIS TNBC cells maintain survival in the face of chemotherapy. TIS was induced and confirmed in Cal51 TNBC cells using the chemotherapeutic paclitaxel (PTX) (Taxol). Mass spectrometry (MS) analysis of EVs harvested from TIS compared with control Cal51 cells was performed using Ingenuity Pathway Analysis and InnateDB programs. We demonstrate that TIS Cal51 cells treated with 75 nM PTX for 7 days became senescent (senescence-associated ß-galactosidase (SA-ß-Gal) positive, Ki67-negative, increased p21 and p16, G2/M cell cycle arrest) and released significantly more EVs (P=0.0002) and exosomes (P=0.0007) than non-senescent control cells. Moreover, TIS cells displayed an increased expression of the multidrug resistance protein 1/p-glycoprotein. MS analysis demonstrated that EVs derived from senescent Cal51 cells contained 142 proteins with a significant increased fold change compared with control EVs. Key proteins included ATPases, annexins, tubulins, integrins, Rabs and insoluble senescence-associated secretory phenotype (SASP) factors. A fluorescent analogue of PTX (Flutax-2) allowed appreciation of the removal of chemotherapy in EVs from senescent cells. Treatment of TIS cells with the exosome biogenesis inhibitor GW4869 resulted in reduced SA-ß-Gal staining (P=0.04). In summary, this study demonstrates that TIS cells release significantly more EVs compared with control cells, containing chemotherapy and key proteins involved in cell proliferation, ATP depletion, apoptosis and the SASP. These findings may partially explain why cancer senescent cells remain viable despite chemotherapeutic challenge.
ABSTRACT
OBJECTIVE: To measure body mass index (BMI) and ambulation changes for a morbidly obese, 47-year-old man with chronic motor-incomplete tetraplegia after gastric sleeve surgery. DESIGN/METHOD: A morbidly obese man, BMI=44 kg m(-)(2), with chronic C5 AIS D tetraplegia underwent elective gastric sleeve surgery. Assessment of BMI and function via the 6-minute walk test (6MWT), 10-meter walk test (10MWT) and ambulation parameters (CIR Systems/GAITRite, Franklin, NJ, USA) was performed preoperatively and at 12, 24, 36 and 52 weeks postoperatively, and additionally after 3 weeks of both a prescribed coached (3 × /week facility based) and a non-coached (3 × /week home based) walking program initiated at 52 weeks. A step activity monitor assessed daily ambulation preoperatively, prior to and during the third and sixth week of the walking program. RESULTS: Results included a 34.3% peak BMI decrease at 52 weeks post surgery and a peak increase in 6MWT distance of 58% at 52 weeks post surgery, 10MWT preferred speed of 56% at 55 weeks and step activity monitor of 82% at 58 weeks post surgery. At 58 weeks, gait data demonstrated a decrease in double limb stance of 38% and decrease in base of support of 72%. CONCLUSION/CLINICAL RELEVANCE: This empirical case assessment of BMI and functional mobility before and after gastric sleeve surgery may encourage further investigation into mobility and general health effects post gastric procedures for people with chronic motor-incomplete spinal cord injury.
Subject(s)
Bariatric Surgery/methods , Gait Disorders, Neurologic/etiology , Obesity/etiology , Obesity/surgery , Quadriplegia/complications , Weight Loss/physiology , Body Mass Index , Follow-Up Studies , Humans , Male , Middle Aged , Quadriplegia/surgery , WalkingABSTRACT
The prognosis for patients multiple myeloma (MM) has improved substantially over the past decade with the development of new, more effective chemotherapeutic agents and regimens that possess a high level of anti-tumor activity. In spite of this important progress, however, nearly all MM patients ultimately relapse, even those who experience a complete response to initial therapy. Management of relapsed MM thus represents a vital aspect of the overall care for patients with MM and a critical area of ongoing scientific and clinical research. This comprehensive manuscript from the International Myeloma Working Group provides detailed recommendations on management of relapsed disease, with sections dedicated to diagnostic evaluation, determinants of therapy, and general approach to patients with specific disease characteristics. In addition, the manuscript provides a summary of evidence from clinical trials that have significantly impacted the field, including those evaluating conventional dose therapies, as well as both autologous and allogeneic stem cell transplantation. Specific recommendations are offered for management of first and second relapse, relapsed and refractory disease, and both autologous and allogeneic transplant. Finally, perspective is provided regarding new agents and promising directions in management of relapsed MM.
Subject(s)
Multiple Myeloma , Practice Guidelines as Topic , Antineoplastic Agents/therapeutic use , Disease Management , Hematopoietic Stem Cell Transplantation/methods , Humans , Multiple Myeloma/diagnosis , Multiple Myeloma/drug therapy , Multiple Myeloma/pathology , Multiple Myeloma/therapy , Recurrence , Salvage Therapy/methodsABSTRACT
BACKGROUND: Chromosomal instability (CIN) has been shown to be associated with drug resistance and poor clinical outcome in several cancer types. However, in oestrogen receptor (ER)-negative breast cancer we have previously demonstrated that extreme CIN is associated with improved clinical outcome, consistent with a negative impact of CIN on tumour fitness and growth. The aim of this current study was to validate this finding using previously defined CIN thresholds in a much larger prospective cohort from a randomised, controlled, clinical trial. PATIENTS AND METHODS: As a surrogate measurement of CIN, dual centromeric fluorescence in situ hybridisation was performed for both chromosomes 2 and 15 on 1173 tumours from the breast cancer TACT trial (CRUK01/001). Each tumour was scored manually and the mean percentage of cells deviating from the modal centromere number was used to define four CIN groups (MCD1-4), where tumours in the MCD4 group were defined as having extreme CIN. RESULTS: In a multivariate analysis of disease-free survival, with a median follow-up of 91 months, increasing CIN was associated with improved outcome in patients with ER-negative cancer (P trend = 0.03). A similar pattern was seen in ER-negative/HER2-negative cancers (Ptrend = 0.007). CONCLUSIONS: This prospective validation cohort study further substantiated the association between extreme CIN and improved outcome in ER-negative breast cancers. Identifying such patients with extreme CIN may help distinguish good from poor prognostic groups, and therefore support treatment and risk stratification in this aggressive breast cancer subtype.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Biomarkers, Tumor/metabolism , Breast Neoplasms/genetics , Breast Neoplasms/mortality , Chromosomal Instability , Receptors, Estrogen/metabolism , Adult , Aged , Aged, 80 and over , Anthracyclines/administration & dosage , Breast Neoplasms/drug therapy , Breast Neoplasms/pathology , Female , Follow-Up Studies , Humans , Immunoenzyme Techniques , In Situ Hybridization, Fluorescence , Middle Aged , Neoplasm Grading , Neoplasm Staging , Prognosis , Prospective Studies , Receptor, ErbB-2/metabolism , Receptors, Progesterone/metabolism , Survival Rate , Taxoids/administration & dosage , Young AdultABSTRACT
STUDY DESIGN: Prospective assessment as part of initial evaluations for randomized-controlled trial participation. OBJECTIVES: To determine the test-retest reliability of peak VO2 testing during both robotically assisted body weight supported treadmill training (RABWSTT) and arm cycle ergometry and to assess whether a relationship exists between these two measurements in individuals with chronic motor incomplete spinal cord injury (CMISCI). METHODS: Twenty-one participants with CMISCI enrolled in a 3- month, RABWSTT randomized-controlled trial. As part of their baseline assessments, individuals underwent VO2 peak assessments twice on separate days during both RABWSTT and arm cycle ergometry using a metabolic cart. RESULTS: Peak oxygen consumption measured at baseline correlated significantly between repeated tests in the RABWSTT (r=0.96, P<0.01) and the arm ergometer (r=0.95, P<0.01). A Pearson correlation (r=0.87, P<0.01) existed between the peak VO2 measurements obtained using RABWSTT and arm ergometry, although Bland-Altman analysis suggested a more limited relationship with a bias of 1.1 favoring arm ergometry. This relationship was stronger for individuals with tetraplegia than for people with paraplegia. CONCLUSION/CLINICAL RELEVANCE: Determination of VO2 peak during both RABWSTT and arm ergometry in individuals with CMISCI is highly reproducible. Furthermore, a moderate correlation exists between peak VO2 measured during RABWSTT and arm cycle ergometry in this population for individuals with tetraplegia. This correlation offers implications for future cardiovascular testing of individuals with CMISCI, as two reliable peak VO2 measurement techniques are possible.
Subject(s)
Exercise Test/methods , Exercise/physiology , Oxygen Consumption/physiology , Spinal Cord Injuries/physiopathology , Spinal Cord Injuries/rehabilitation , Adult , Aged , Arm/physiopathology , Chronic Disease , Female , Humans , Lower Extremity/physiopathology , Male , Middle Aged , Paraplegia/diagnosis , Paraplegia/etiology , Paraplegia/physiopathology , Paraplegia/rehabilitation , Prospective Studies , Quadriplegia/diagnosis , Quadriplegia/etiology , Quadriplegia/physiopathology , Quadriplegia/rehabilitation , Randomized Controlled Trials as Topic , Reproducibility of Results , Robotics , Spinal Cord Injuries/complications , Spinal Cord Injuries/diagnosisABSTRACT
The indirect exchange interaction is one of the key factors in determining the overall alignment of magnetic impurities embedded in metallic host materials. In this work we examine the range of this interaction in magnetically doped graphene systems in the presence of armchair edges using a combination of analytical and numerical Green function approaches. We consider both a semi-infinite sheet of graphene with a single armchair edge, and also quasi-one-dimensional armchair-edged graphene nanoribbons (GNRs). While we find signals of the bulk decay rate in semi-infinite graphene and signals of the expected one-dimensional decay rate in GNRs, we also find an unusually rapid decay for certain instances in both, which manifests itself whenever the impurities are located at sites which are a multiple of three atoms from the edge. This decay behavior emerges from both the analytic and numerical calculations, and the result for semi-infinite graphene can be interpreted as an intermediate case between ribbon and bulk systems.
ABSTRACT
BACKGROUND: Invasive lobular breast cancer (ILC) and lobular carcinoma in situ (LCIS) are characterised by loss of E-cadherin expression. However germline CDH1 mutations are rare in cases of ILC with no family history of hereditary diffuse gastric cancer (HDGC) and have not been described in women with LCIS. METHODS: We screened the CDH1 gene in 50 cases of bilateral LCIS/ILC using Sanger sequencing and MLPA. RESULTS: Sanger sequencing revealed four pathogenic germline mutations, including a novel splicing mutation (c.48+1G>A). The remaining three (c.1465insC, c.1942G>T, c.2398delC) have been previously described. All four cases had bilateral LCIS +/- ILC and no family history of gastric cancer. CONCLUSION: CDH1 germline mutations have not been previously described in women with LCIS. We have shown that germline CDH1 mutations are associated with early onset of bilateral LCIS with or without ILC in women without a family history of gastric cancer. CDH1 mutation screening should be considered in women with early onset of bilateral LCIS/ILC with no family history of HDGC.
Subject(s)
Breast Neoplasms/genetics , Cadherins/genetics , Carcinoma in Situ/genetics , Carcinoma, Lobular/genetics , Antigens, CD , Base Sequence , Breast Neoplasms/pathology , Carcinoma, Lobular/pathology , Female , Germ-Line Mutation/genetics , Humans , Middle Aged , Sequence Analysis, DNAABSTRACT
We present a pulsed fiber laser system with average power up to 265 W, pulse energy up to 10.6 mJ, pulse duration adjustable in the range 500 ps-500 ns, repetition rate fully controllable from single-shot operation up to 1 MHz, and the ability to control peak power independently of pulse energy. The system has a compact, all-spliced construction. Such a versatile laser will have wide applications in materials processing.
ABSTRACT
BACKGROUND: The Laboratory modernisation process in Ireland will include point of care testing (POCT) as one of its central tenets. However, a previous baseline survey showed that POCT was under-resourced particularly with respect to information technology (IT) and staffing. AIMS: An audit was undertaken to see if POCT services had improved since the publication of National Guidelines and if such services were ready for the major changes in laboratory medicine as envisaged by the Health Service Executive. METHODS: The 15 recommendations of the 2007 Guidelines were used as a template for a questionnaire, which was distributed by the Irish External Quality Assessment Scheme. RESULTS: Thirty-nine of a possible 45 acute hospitals replied. Only a quarter of respondent hospitals had POCT committees, however, allocation of staff to POCT had doubled since the first baseline survey. Poor IT infrastructure, the use of unapproved devices, and low levels of adverse incident reporting were still major issues. CONCLUSIONS: Point of care testing remains under-resourced, despite the roll out of such devices throughout the health service including primary care. The present high standards of laboratory medicine may not be maintained if the quality and cost-effectiveness of POCT is not controlled. Adherence to national Guidelines and adequate resourcing is essential to ensure patient safety.
Subject(s)
Clinical Laboratory Services/standards , Laboratories, Hospital/standards , Point-of-Care Systems/standards , Clinical Laboratory Services/statistics & numerical data , Diffusion of Innovation , Guideline Adherence , Health Care Surveys , Ireland , Laboratories, Hospital/statistics & numerical data , Medical Audit , Point-of-Care Systems/statistics & numerical data , Practice Guidelines as Topic , Practice Patterns, Physicians'/standards , Quality Improvement , Quality Indicators, Health CareABSTRACT
The recently updated Durie/Salmon PLUS staging system published in 2006 highlights the many advances that have been made in the imaging of multiple myeloma, a common malignancy of plasma cells. In this article, we shall focus primarily on the more sensitive and specific whole-body imaging techniques, including whole-body computed tomography, whole-body magnetic resonance imaging, and positron emission computed tomography. We shall also discuss new and emerging imaging techniques and future developments in the radiological assessment of multiple myeloma.
ABSTRACT
BACKGROUND: "Guidelines for safe and effective management and use of point of care testing" have been recently launched in Ireland. AIMS: To survey point of care testing (POCT) services in the Republic of Ireland. METHODS: A questionnaire covering accreditation status, existence of POCT committees, quality management systems, and staff resources was distributed by the Irish External Quality Assessment Scheme (IEQAS). RESULTS: Of those that returned completed questionnaires, 56% had assigned specific POCT responsibilities to designated staff. Most support was for blood gases and glucose analysis. Compared with other published studies, Irish laboratories gave similar support for blood gases, less for glucose and much less for urinalysis. CONCLUSIONS: This survey demonstrated poor IT support for POCT. The majority of the respondents (78%) were dissatisfied with the quality of the POCT service in their institution.
Subject(s)
Point-of-Care Systems/statistics & numerical data , Clinical Governance , Guideline Adherence , Humans , Ireland , Practice Guidelines as TopicABSTRACT
BACKGROUND: The incidence of colorectal cancer (CRC) has been increasing. We evaluated uptake rates and outcomes of faecal immunochemical test (FIT) and Guaiac test (gFOBT) kits as part of a two-step CRC screening. METHODS: A 3-year CRC screening program for a defined population of construction workers was conducted. Those satisfying the inclusion criteria were provided with gFOBT or FIT kits. Individuals testing positive were invited for a colonoscopy. RESULTS: A total of 909 faecal testing kits were distributed. Age range was 53-60 years. Compliance rate was higher for FIT (58.3%) as compared to gFOBT (46.7%) (p = 0.0006). FIT detected adenomatous polyps and CRC in 37.5 and 25%, respectively, whereas; gFOBT detected 23.5 and 18%. Colonoscopies were normal in 53 and 25% tested positive by gFOBT and FIT, respectively (p = 0.016). CONCLUSION: The FIT was more cost-effective when compared with gFOBT with higher return rate, sensitivity and specificity. A comparative study of faecal occult blood kits in a CRC screening program in a healthy cohort of construction workers.
Subject(s)
Colorectal Neoplasms/diagnosis , Occult Blood , Occupational Health , Cohort Studies , Colectomy , Colorectal Neoplasms/epidemiology , Colorectal Neoplasms/surgery , Guaiac , Humans , Indicators and Reagents , Male , Mass Screening/methods , Middle AgedABSTRACT
We report the case of a 35 year patient from Nigeria who presented with fever and splenomegaly. The initial diagnosis was Salmonellosis. However, relapsing symptoms lead to a re-evaluation and ultimately a diagnosis of Multicentric Castleman's Disease (MCD). There is no gold standard treatment but our patient responded to Rituximab and Highly active anti-retroviral therapy. MCD is a rare, aggressive disease that should be considered in a HIV positive patient presenting with fever and significant lymphadenopathy.
Subject(s)
Antibodies, Monoclonal/therapeutic use , Antiretroviral Therapy, Highly Active , Castleman Disease/diagnosis , Herpesvirus 8, Human , Immunologic Factors/therapeutic use , Adult , Anti-Infective Agents/therapeutic use , Antibodies, Monoclonal, Murine-Derived , Castleman Disease/drug therapy , Castleman Disease/pathology , Castleman Disease/surgery , Ciprofloxacin/therapeutic use , Humans , Male , Rituximab , SplenomegalyABSTRACT
The seminal 'two-hit hypothesis' implicitly assumes that bi-allelic tumour suppressor gene (TSG) mutations cause loss of protein function. All subsequent events in that tumour therefore take place on an essentially null background for that TSG protein. We have shown that the two-hit model requires modification for the APC TSG, because mutant APC proteins probably retain some function and the two hits are co-selected to produce an optimal level of Wnt activation. We wondered whether the optimal Wnt level might change during tumour progression, leading to selection for more than two hits at the APC locus. Comprehensive screening of a panel of colorectal cancer (CRC) cell lines and primary CRCs showed that some had indeed acquired third hits at APC. These third hits were mostly copy number gains or deletions, but could be protein-truncating mutations. Third hits were significantly less common when the second hit at APC had arisen by copy-neutral loss of heterozygosity. Both polyploid and near-diploid CRCs had third hits, and the third hits did not simply arise as a result of acquiring a polyploid karyotype. The third hits affected mRNA and protein levels, with potential functional consequences for Wnt signalling and tumour growth. Although some third hits were probably secondary to genomic instability, others did appear specifically to target APC. Whilst it is generally believed that tumours develop and progress through stepwise accumulation of mutations in different functional pathways, it also seems that repeated targeting of the same pathway and/or gene is selected in some cancers.
Subject(s)
Adenoma/genetics , Adenomatous Polyposis Coli Protein/genetics , Carcinoma/genetics , Colorectal Neoplasms/genetics , Loss of Heterozygosity , Models, Genetic , Adenoma/pathology , Alleles , Carcinoma/pathology , Cell Line, Tumor , Cell Proliferation , Colorectal Neoplasms/pathology , Diploidy , Gene Dosage , Genomics , Humans , Mutation , Polyploidy , Wnt Proteins/genetics , Wnt Proteins/metabolismABSTRACT
AIM: The aim of the study is to assess the feasibility of whole-body low-dose computed tomography (WBLDCT) in the diagnosis and staging of multiple myeloma and compare to skeletal survey (SS), using bone marrow biopsy and whole-body magnetic resonance imaging (WBMRI; where available) as gold standard. MATERIALS AND METHODS: Patients referred over an 18-month period for investigation of suspected multiple myeloma or restaging of myeloma were randomized to undergo one of two WBLDCT protocols using high kVp, low mAs technique (140 kVp, 14 mAs; or 140 kVp, 25 mAs). Recent WBMRI scans were reviewed in 23 cases. Each imaging modality was assessed by two radiologists in consensus and scored from 0-3 (0 = normal, 1 = 1-4 lesions, 2 = 5-20 lesions, 3 >or= 20 lesions/diffuse disease) in ten anatomical areas. Overall stage of disease, image quality score, and the degree of confidence of diagnosis were recorded. Diagnostic accuracy of skeletal survey and WBLDCT were determined using a gold standard of bone marrow biopsy and distribution of disease was compared to WBMRI. RESULTS: Thirty-nine patients were evaluated. WBLDCT identified more osteolytic lesions than skeletal survey with a greater degree of diagnostic confidence and led to restaging in 18 instances (16 upstaged, two downstaged). In those with recent WBMRI, distribution of disease on WBLDCT showed superior correlation with WBMRI when compared with SS. Overall reader impression of stage on WBLDCT showed significant correlation with WBMRI (kappa = 0.454, p < 0.05). WBLDCT provided complementary information to WBMRI in nine patients with normal marrow signal following treatment response, but which were shown to have diffuse residual cortical abnormalities on CT. CONCLUSION: WBLDCT at effective doses lower than previously reported, is superior to SS at detecting osteolytic lesions and at determining overall stage of multiple myeloma, and provides complementary information to WBMRI.
Subject(s)
Magnetic Resonance Imaging/methods , Multiple Myeloma/diagnosis , Tomography, X-Ray Computed/methods , Whole Body Imaging/methods , Adult , Aged , Aged, 80 and over , Biopsy , Bone Marrow/pathology , Chi-Square Distribution , Feasibility Studies , Female , Humans , Image Interpretation, Computer-Assisted , Male , Middle Aged , Multiple Myeloma/diagnostic imaging , Multiple Myeloma/pathology , Neoplasm Staging , Radiation Dosage , Sensitivity and SpecificityABSTRACT
We analysed chromosome 16q in 106 breast cancers using tiling-path array-comparative genomic hybridization (aCGH). About 80% of ductal cancers (IDCs) and all lobular cancers (ILCs) lost at least part of 16q. Grade I (GI) IDCs and ILCs often lost the whole chromosome arm. Grade II (GII) and grade III (GIII) IDCs showed less frequent whole-arm loss, but often had complex changes, typically small regions of gain together with larger regions of loss. The boundaries of gains/losses tended to cluster, common sites being 54.5-55.5 Mb and 57.4-58.8 Mb. Overall, the peak frequency of loss (83% cancers) occurred at 61.9-62.9 Mb. We also found several 'minimal' regions of loss/gain. However, no mutations in candidate genes (TRADD, CDH5, CDH8 and CDH11) were detected. Cluster analysis based on copy number changes identified a large group of cancers that had lost most of 16q, and two smaller groups (one with few changes, one with a tendency to show copy number gain). Although all morphological types occurred in each cluster group, IDCs (especially GII/GIII) were relatively overrepresented in the smaller groups. Cluster groups were not independently associated with survival. Use of tiling-path aCGH prompted re-evaluation of the hypothetical pathways of breast carcinogenesis. ILCs have the simplest changes on 16q and probably diverge from the IDC lineage close to the stage of 16q loss. Higher-grade IDCs probably develop from low-grade lesions in most cases, but there remains evidence that some GII/GIII IDCs arise without a GI precursor.
Subject(s)
Breast Neoplasms/genetics , Carcinoma, Ductal, Breast/genetics , Carcinoma, Lobular/genetics , Chromosomes, Human, Pair 16 , Neoplasm Invasiveness/genetics , Nucleic Acid Hybridization/methods , Tissue Array Analysis/methods , Chromosome Aberrations , Chromosome Breakage , Cluster Analysis , DNA, Neoplasm , Gene Amplification , Gene Deletion , Genetic Linkage , Humans , Loss of Heterozygosity , Models, Statistical , Neoplasm StagingABSTRACT
Exonuclease 1 (EXO1) is a candidate gene for colorectal tumor susceptibility because it is believed to play a role in mismatch repair. There have been several studies investigating the role of EXO1 in mismatch repair but few investigating its role in causing clinical disease. In one recent study, germline variants of EXO1 were reported to be associated with predisposition to colorectal cancer in families with phenotypes similar to hereditary nonpolyposis colon cancer (HNPCC). We recently identified nine individuals from two British families with multiple cutaneous and uterine leiomyomatosis with independently arising heterozygous germline deletions of 1q42.3 approximately q43 encompassing not only FH, the multiple leiomyomatosis-associated gene, but also several flanking genes, including EXO1. We investigated these families for any indication of predisposition to colorectal cancer or other HNPCC spectrum cancers by means of detailed questionnaires, interviews, and examination of EXO1-null skin leiomyomata for microsatellite instability (MSI). No individual in these families had developed colorectal cancer or known colorectal adenomas, and none had any symptoms warranting gastrointestinal or other investigation. EXO1-null tumors showed no evidence of MSI. This study questions the functional significance of previously reported variants of EXO1 reported in HNPCC-like families and suggests that in humans there may be other as yet undiscovered proteins that have exonuclease function overlapping with that of EXO1 in DNA mismatch repair. Also of interest is the absence of phenotypic abnormality apart from multiple leiomyomatosis in any deletion carrier even though the adjacent genes RGS7, KMO, CHML, and OPN3 were also deleted.