A clickable melphalan for monitoring DNA interstrand crosslink accumulation and detecting ICL repair defects in Fanconi anemia patient cells.

Fanconi anemia (FA) is a genetic disorder associated with developmental defects, bone marrow failure and cancer. The FA pathway is crucial for the repair of DNA interstrand crosslinks (ICLs). In this study, we have developed and characterized a new tool to investigate ICL repair: a clickable version of the crosslinking agent melphalan which we name click-melphalan. Our results demonstrate that click-melphalan is as effective as its unmodified counterpart in generating ICLs and associated toxicity. The lesions induced by click-melphalan can be detected in cells by post-labelling with a fluorescent reporter and quantified using flow cytometry. Since click-melphalan induces both ICLs and monoadducts, we generated click-mono-melphalan, which only induces monoadducts, in order to distinguish between the two types of DNA repair. By using both molecules, we show that FANCD2 knock-out cells are deficient in removing click-melphalan-induced lesions. We also found that these cells display a delay in repairing click-mono-melphalan-induced monoadducts. Our data further revealed that the presence of unrepaired ICLs inhibits monoadduct repair. Finally, our study demonstrates that these clickable molecules can differentiate intrinsic DNA repair deficiencies in primary FA patient cells from those in primary xeroderma pigmentosum patient cells. As such, these molecules may have potential for developing diagnostic tests.

Clonal hematopoiesis driven by chromosome 1q/MDM4 trisomy defines a canonical route toward leukemia in Fanconi anemia.

Fanconi anemia (FA) patients experience chromosome instability, yielding hematopoietic stem/progenitor cell (HSPC) exhaustion and predisposition to poor-prognosis myeloid leukemia. Based on a longitudinal cohort of 335 patients, we performed clinical, genomic, and functional studies in 62 patients with clonal evolution. We found a unique pattern of somatic structural variants and mutations that shares features of BRCA-related cancers, the FA-hallmark being unbalanced, microhomology-mediated translocations driving copy-number alterations. Half the patients developed chromosome 1q gain, driving clonal hematopoiesis through MDM4 trisomy downmodulating p53 signaling later followed by secondary acute myeloid lukemia genomic alterations. Functionally, MDM4 triplication conferred greater fitness to murine and human primary FA HSPCs, rescued inflammation-mediated bone marrow failure, and drove clonal dominance in FA mouse models, while targeting MDM4 impaired leukemia cells in vitro and in vivo. Our results identify a linear route toward secondary leukemogenesis whereby early MDM4-driven downregulation of basal p53 activation plays a pivotal role, opening monitoring and therapeutic prospects.

Salud mental de adolescentes y jóvenes víctimas de desplazamiento forzado en Colombia / Mental Health of Adolescents and Young People Victims of Forced Displacement in Colombia

Resumen La exposición a situaciones de vulnerabilidad y violencia, como el desplazamiento forzado, generan en la población víctima efectos nocivos para su salud mental. El objetivo del presente estudio es describir el estado actual de la salud mental y algunos factores sociodemográficos y del entorno asociados, de 471 adolescentes y jóvenes entre 13 y 28 años, víctimas de desplazamiento forzado en tres ciudades colombianas. Se aplicó la entrevista Composite International Diagnostic Interview (CIDI), versión CAPI (Computer Assisted Personal Interview); un cuestionario ad hoc sobre aspectos del desplazamiento forzado y el consumo de sustancias psicoactivas; la escala de funcionamiento familiar APGAR y la escala MOS (Medical Outcomes Study) de apoyo social. Se encontró una prevalencia de cualquier trastorno mental en el último año del 24,4% y cualquier trastorno por uso de sustancias del 4,7%. Los trastornos más prevalentes fueron fobia específica (6,8%), trastorno por estrés postraumático (5,7%) y trastorno depresivo mayor (5,1%). La dependencia a la marihuana se presentó en 2,1% de los participantes y el abuso de alcohol en 1,9%. Un 14,6% de los adolescentes y jóvenes víctimas de desplazamiento forzado han pensado suicidarse alguna vez en la vida. Ser hombre, menor de edad, con buen funcionamiento familiar y apoyo social adecuado, fueron factores protectores para la presencia de trastornos mentales.

Abstract Exposure to vulnerable and violent events, such as forced displacement, generate several adverse effects on the mental health of victim population. The objective of this study is to describe the current mental health condition and some associated sociodemographic and environmental factors in 471 adolescents and young people between 13 and 28 years of age, who have been victims of forced displacement in three Colombian cities. The Composite International Diagnostic Interview (CIDI) interview, CAPI (Computer Assisted Personal Interview) version was administered; an ad hoc questionnaire on aspects of forced displacement and the consumption of psychoactive substances; the APGAR family function scale and the MOS (Medical Outcomes Study) scale of social support. It was found a prevalence of any mental disorder in the last years of 24.4% and any substance use disorder of 4.7%. The most prevalent disorders were specific phobia (6.8%), post-traumatic stress disorder (5.7%) and major depressive disorder (5.1%). Dependence on marijuana was found at 2.1% and alcohol abuse at 1.9%. 14.6% of adolescents and young victims of forced displacement have considered committing suicide at some point along their lives. Being a minor- age man, with a functional family and adequate social support, were protective factors from mental disorders.

Germline DDX41 mutations define a significant entity within adult MDS/AML patients.

Germline DDX41 mutations are involved in familial myelodysplastic syndromes (MDSs) and acute myeloid leukemias (AMLs). We analyzed the prevalence and characteristics of DDX41-related myeloid malignancies in an unselected cohort of 1385 patients with MDS or AML. Using targeted next-generation sequencing, we identified 28 different germline DDX41 variants in 43 unrelated patients, which we classified as causal (n = 21) or unknown significance (n = 7) variants. We focused on the 33 patients having causal variants, representing 2.4% of our cohort. The median age was 69 years; most patients were men (79%). Only 9 patients (27%) had a family history of hematological malignancy, and 15 (46%) had a personal history of cytopenia years before MDS/AML diagnosis. Most patients had a normal karyotype (85%), and the most frequent somatic alteration was a second DDX41 mutation (79%). High-risk DDX41 MDS/AML patients treated with intensive chemotherapy (n = 9) or azacitidine (n = 11) had an overall response rate of 100% or 73%, respectively, with a median overall survival of 5.2 years. Our study highlights that germline DDX41 mutations are relatively common in adult MDS/AML, often without known family history, arguing for systematic screening. Salient features of DDX41-related myeloid malignancies include male preponderance, frequent preexisting cytopenia, additional somatic DDX41 mutation, and relatively good outcome.

Reduced recruitment of 53BP1 during interstrand crosslink repair is associated with genetically inherited attenuation of mitomycin C sensitivity in a family with Fanconi anemia.

The Fanconi anemia (FA) pathway is implicated in the repair of DNA interstrand crosslinks (ICL). In this process, it has been shown that FA factors regulate the choice for DNA double strand break repair towards homologous recombination (HR). As this mechanism is impaired in FA deficient cells exposed to crosslinking agents, an inappropriate usage of non-homologous end joining (NHEJ) leads to the accumulation of toxic chromosomal abnormalities. We studied a family with two FANCG patients and found a genetically inherited attenuation of mitomycin C sensitivity resulting in-vitro in an attenuated phenotype for one patient or in increased resistance for two healthy relatives. A heterozygous mutation in ATM was identified in these 3 subjects but was not directly linked to the observed phenotype. However, the attenuation of ICL sensitivity was associated with a reduced recruitment of 53BP1 during the course of ICL repair, and increased HR levels. These results further demonstrate the importance of favoring HR over NHEJ for the survival of cells challenged with ICLs.

Biallelic truncating FANCM mutations cause early-onset cancer but not Fanconi anemia.

PurposeMutations in genes involved in Fanconi anemia (FA)/BRCA DNA repair pathway cause cancer susceptibility diseases including familial breast cancer and Fanconi anemia (FA). A single FA patient with biallelic FANCM mutations was reported in 2005 but concurrent FANCA pathogenic mutations precluded assignment of FANCM as an FA gene. Here we report three individuals with biallelic FANCM truncating mutations who developed early-onset cancer and toxicity to chemotherapy but did not present congenital malformations or any hematological phenotype suggestive of FA.MethodsChromosomal breakages, interstrand crosslink sensitivity, and FANCD2 monoubiquitination were assessed in primary fibroblasts. Mutation analysis was achieved through Sanger sequencing. Genetic complementation of patient-derived cells was performed by lentiviral mediated transduction of wild-type FANCM complementary DNA followed by functional studies.ResultsPatient-derived cells exhibited chromosomal fragility, hypersensitivity to interstrand crosslinks, and impaired FANCD2 monoubiquitination. We identified two homozygous mutations (c.2586_2589del4; p.Lys863Ilefs*12 and c.1506_1507insTA; p.Ile503*) in FANCM as the cause of the cellular phenotype. Patient-derived cells were genetically complemented upon wild-type FANCM complementary DNA expression.ConclusionLoss-of-function mutations in FANCM cause a cancer predisposition syndrome clinically distinct from bona fide FA. Care should be taken with chemotherapy and radiation treatments in these patients due to expected acute toxicity.

A landscape of germ line mutations in a cohort of inherited bone marrow failure patients.

Bone marrow (BM) failure (BMF) in children and young adults is often suspected to be inherited, but in many cases diagnosis remains uncertain. We studied a cohort of 179 patients (from 173 families) with BMF of suspected inherited origin but unresolved diagnosis after medical evaluation and Fanconi anemia exclusion. All patients had cytopenias, and 12.0% presented ≥5% BM blast cells. Median age at genetic evaluation was 11 years; 20.7% of patients were aged ≤2 years and 36.9% were ≥18 years. We analyzed genomic DNA from skin fibroblasts using whole-exome sequencing, and were able to assign a causal or likely causal germ line mutation in 86 patients (48.0%), involving a total of 28 genes. These included genes in familial hematopoietic disorders (GATA2, RUNX1), telomeropathies (TERC, TERT, RTEL1), ribosome disorders (SBDS, DNAJC21, RPL5), and DNA repair deficiency (LIG4). Many patients had an atypical presentation, and the mutated gene was often not clinically suspected. We also found mutations in genes seldom reported in inherited BMF (IBMF), such as SAMD9 and SAMD9L (N = 16 of the 86 patients, 18.6%), MECOM/EVI1 (N = 6, 7.0%), and ERCC6L2 (N = 7, 8.1%), each of which was associated with a distinct natural history; SAMD9 and SAMD9L patients often experienced transient aplasia and monosomy 7, whereas MECOM patients presented early-onset severe aplastic anemia, and ERCC6L2 patients, mild pancytopenia with myelodysplasia. This study broadens the molecular and clinical portrait of IBMF syndromes and sheds light on newly recognized disease entities. Using a high-throughput sequencing screen to implement precision medicine at diagnosis can improve patient management and family counseling.

Clima escolar y funcionalidad familiar como factores asociados a la intimidación escolar en Antioquia, Colombia / School Climate and Family Functionality as Associated Factors to Bullying in Students of Antioquia, Colombia / Clima escolar e funcionalidade familiar como fatores associados à intimidação escolar em Antioquia, Colômbia

Objetivo. Determinar la relación entre clima escolar, funcionalidad familiar e intimidación escolar en estudiantes de Antioquia (Colombia). Método. Se encuestaron 2421 estudiantes, con edades comprendidas entre los 9 y los 18 años, que asistían a instituciones educativas en las nueve subregiones del departamento. Los instrumentos utilizados fueron la Escala de Clima Escolar, APGAR familiar y CIE-A abreviada. Resultados. Los análisis multivariados y de regresión logística binomial encontraron que en los estudiantes antioqueños que reportaron un clima escolar inadecuado tienen una probabilidad de riesgo de presentar alta intimidación escolar cuatro veces mayor, mientras que la probabilidad de riesgo medio de intimidación es tres veces mayor, frente a los jóvenes que reportaron una percepción de un clima escolar adecuado. A su vez, el reporte de disfunción familiar indicó asociación con un clima escolar inadecuado. Conclusión. Se evidenció no solo una estrecha vinculación entre la percepción de un clima escolar inadecuado y la aparición de la intimidación escolar en este contexto, sino que la funcionalidad familiar es la base fundamental para resolver las dificultades que en el día a día se presentan en el ambiente escolar.

Objective. To determine the existing relationship between school climate and family functioning with school bullying in Antioquia Colombia. Method. A transverse study was carried out in the educational institutions of nine subregions of Antioquia - Colombia. The total sample was 2421 students in Antioquia between the 9 and 18 years old. The instruments used were the Scale of School Climate (SES), APGAR and CIE - A Short version. Results. The multivariate and binomial logistic regression analysis found that students who reported an inadequate school climate have four times more the risk of being intimidated or bullied at school, when compared to the students who reported a perception of an adequate school climate. Likewise, the students who identified inadequate school climates are three times more at risk of school intimidation on average. Also, the report of familiar dysfunction indicated an association with inadequate school climate. Conclusion. The close link between the perception of inadequate school climate and the emergence of bullying in the school context is evident; secondly, family functionality is established as a key to resolve the difficulties that are presented in the daily school environment.

Escopo. Determinar a associação existente entre clima escolar, funcionalidade familiar e intimidação escolar em estudantes de Antioquia (Colômbia). Metodologia. Para isto, foram entrevistados 2421 estudantes, com idades entre os 9 e os 18 anos, de instituições educativas nas nove sub-regiões do departamento. Os instrumentos utilizados foram a Escala de Clima Escolar, APGAR familiar e CIE-A abreviada. Resultados. Análises multivariadas e de regressão logística binomial encontraram que os estudantes de Antioquia que reportaram um clima escolar inadequado têm quatro vezes mais o risco de presentar uma alta intimidação escolar, com respeito aos jovens que reportam uma percepção de um clima escolar adequado. Do mesmo jeito, os estudantes com pontuações de clima escolar inadequado, têm três vezes mais a probabilidade de risco médio de intimidação escolar. Na sua vez, o reporte de disfunção familiar indica associação com um clima escolar inadequado. Conclusão. Foi evidenciada a estreita vinculação entre a percepção de um clima escolar inadequado e a aparição da intimidação escolar neste contexto; em segundo lugar, a funcionalidade familiar constitui uma base fundamental para resolver as dificuldades que no dia a dia apresentam-se no ambiente escolar.

Conceptualización de ciclo vital familiar: una mirada a la producción durante el periodo comprendido entre los años 2002 a 2015 / Conceptualization of family life cycle: a view of the production during the period between 2002 and 2015

El presente trabajo es el resultado de un proceso de investigación teórico descriptiva de tipo documental, en el cual se rastrearon y analizaron diferentes estudios publicados durante los años 2002 a 2015 en relación con el tema ciclo vital familiar (CVF). Se analizaron 45 artículos y textos teóricos. A partir del proceso de codificación y análisis se derivan tres núcleos temáticos: Definición de CVF; Etapas del CVF y Nuevas apuestas conceptuales en torno a éste. Se presenta al ciclo vital familiar desde dos perspectivas, como teorización que permite discernir el desarrollo de la familia a lo largo de su existencia, a través de etapas, y otra que implica cuestionar la validez contemporánea de esta teoría en la sociedad dados sus cambios sociales, culturales, económicos, entre otros.

This study is the result of a process of theoretical descriptive documentary research, in which different researches published during the years 2002-2015 in relation to the subject family life cycle (FLC) were tracked and analyzed. 45 articles and theoretical texts were analyzed. From the process of coding and analysis three contents have been derived: Definition of FLC, FLC stages and new conceptual challenges on this. The family life cycle is presented from two perspectives, as theorizing that can discern the development of the family throughout its existence, through stages, and another that involves questioning the contemporary validity of this theory in society, taken into account social, cultural, and economic changes, among others.

La familia como factor predictor de la intimidación escolar en Antioquia (Colombia) / The family as a predictor of bullying in Antioquia (Colombia)

Objetivo: Se realizó una investigación que buscaba determinar la prevalencia de la intimidación escolar en Antioquia y la relación de la función familiar en la aparición de este fenómeno. Diseño del estudio: Estudio transversal comparativo. Participantes: La población de estudio fueron todos los estudiantes matriculados en los grados de 5° a 9° de las instituciones educativas del Departamento de Antioquia durante el año 2013. Para la selección de la muestra final se realizó un muestreo polietápico, para una muestra final total de 3.222 estudiantes. Mediciones principales: Se evaluó la funcionalidad familiar mediante el instrumento APGAR familiar y la prevalencia de la Intimidación escolar a través del cuestionario CIE A abreviado, conformado por tres categorías de evaluación: victimización por intimidación, sintomatología asociada a la Intimidación escolar como ansiedad, depresión, estrés postraumático y también efectos sobre autoestima y, finalmente, el tercer componente, intimidación por respondientes, el cual explora variables sobre formas de violencia por parte de las personas que realizan acciones de intimidación escolar a otros pares. Resultados: El 46 % de los escolares con riesgo alto de bullying, el 43 % con riesgo medio y el 25 % con riesgo bajo, tienen disfunción familiar moderada a grave. A su vez, la disfunción familiar grave está fuertemente asociada con el riesgo de intimidación escolar en los escolares de Antioquia, denotando con ello que los escolares expuestos a disfunción familiar tienen menos estrategias para relacionarse, sin utilizar la agresión. Conclusiones: Las relaciones estrechas entre los miembros de la familia se encuentran fuertemente relacionadas con las estrategias de vinculación, que permiten afrontar situaciones conflictivas en diversos escenarios, entre ellos el de mayor demanda en la vida cotidiana de los adolescentes, como lo es el escolar. Por tanto, con el acompañamiento decidido de la familia, podría pensarse que los niños y adolescentes resuelvan las situaciones de agresión escolar con estrategias diferentes al bullying (AU)

Objective: To determine the prevalence of bullying in Antioquia and the relationship of the family role in the development of this phenomenon. Study design: Cross-sectional study. Participants: Students enrolled in grades 5th to 9th of educational institutions in the Department of Antioquia in 2013. The final sample was made through a multistage sampling with a total of 3222 students. Main Measures: The family functioning was assessed using the familiar APGAR instrument, and the prevalence of school bullying through the questionnaire CIE A (abbreviated) that consists of three assessment categories: victimization, symptoms associated with school bullying as: anxiety, depression, PTSD and self-esteem, and finally, Intimidation, which explores variables on forms of violence by people performing bullying actions to other pairs . Results: 46% of the students with high risk of bullying, 43% of students with medium risk, and 25% of students with low risk have moderate to severe family dysfunction. At the same time, severe family dysfunction is strongly associated with the risk of bullying at school, meaning that children exposed to family dysfunction have fewer strategies to interact without using aggression. Conclusions: The close relationships between family members are closely related to linking strategies that allow addressing conflicts in different contexts, including the school as the most important in the daily lives of adolescents. Therefore, with the strong support of the family, children and adolescents resolve situations of aggression with strategies different than bullying (AU)

Primary microcephaly, impaired DNA replication, and genomic instability caused by compound heterozygous ATR mutations.

Ataxia telangiectasia-mutated (ATM) and ataxia telangiectasia and Rad3-related (ATR) kinases are two key regulators of DNA-damage responses (DDR) that are mainly activated in response to DNA double-strand breaks and single-stranded DNA damages, respectively. Seckel syndrome, a rare genetic disorder characterized by a microcephaly and a markedly reduced body size, has been associated with defective ATR-dependent DNA damage signaling. However, the only human genetic ATR defect reported so far is a hypomorphic splicing mutation identified in five related individuals with Seckel syndrome. Here, we report the first case of primary microcephaly with compound heterozygous mutations in ATR: a 540 kb genomic deletion on one allele and a missense mutation leading to splice dysregulation on the other, which ultimately lead to a sharp decrease in ATR expression. DNA combing technology revealed a profound spontaneous alteration of several DNA replication parameters in patient's cells and FISH analyses highlighted the genomic instability caused by ATR deficiency. Collectively, our results emphasize the crucial role for ATR in the control of DNA replication, and reinforce the complementary and nonredundant contributions of ATM and ATR in human cells to face DNA damages and warrant genome integrity.

Validación de un cuestionario breve para detectar intimidación escolar / Validation of a Short Questionnaire to detect School Bullying

Dado el reconocimiento internacional y nacional en torno al fenómeno de Bullying, se precisa el diseño y validación en contexto de instrumentos de tamizaje. La mayoría de escalas existentes para la medición de Bullying en población escolar son extensas en contenido y en el tiempo de aplicación. En esta investigación se logra validar un instrumento breve y de corta duración para la detección de la intimidación escolar; se redujo el número de preguntas del cuestionario de intimidación escolar CIE-A de Cuevas. El análisis factorial confirmó la existencia de tres dimensiones: intimidación, sintomatología y la intimidación por parte de respondientes.

Given the international and national recognition on the phenomenon of Bullying, is require the design and validation of screening instruments in context, due to the majority of existing scales for the measurement of Bullying in school population are extensive in content and application time. This research will validate a brief and short instrument for the detection of bullying; the number of the CIE-A questionnaire´s questions was reduced. The Factorial analysis confirmed the existence of three dimensions: intimidation, Symptomatology and the intimidation by bullies.

Bone marrow failure in Fanconi anemia is triggered by an exacerbated p53/p21 DNA damage response that impairs hematopoietic stem and progenitor cells.

Fanconi anemia (FA) is an inherited DNA repair deficiency syndrome. FA patients undergo progressive bone marrow failure (BMF) during childhood, which frequently requires allogeneic hematopoietic stem cell transplantation. The pathogenesis of this BMF has been elusive to date. Here we found that FA patients exhibit a profound defect in hematopoietic stem and progenitor cells (HSPCs) that is present before the onset of clinical BMF. In response to replicative stress and unresolved DNA damage, p53 is hyperactivated in FA cells and triggers a late p21(Cdkn1a)-dependent G0/G1 cell-cycle arrest. Knockdown of p53 rescued the HSPC defects observed in several in vitro and in vivo models, including human FA or FA-like cells. Taken together, our results identify an exacerbated p53/p21 "physiological" response to cellular stress and DNA damage accumulation as a central mechanism for progressive HSPC elimination in FA patients, and have implications for clinical care.

Heterogeneous telomere defects in patients with severe forms of dyskeratosis congenita.

BACKGROUND: Telomeres represent the tips of linear chromosomes. In human subjects telomere maintenance deficiency leads to dyskeratosis congenita (DC), a rare genetic disorder characterized by progressive bone marrow failure, accelerated aging, and cancer predisposition. Hoyeraal-Hreidarsson syndrome (HH) is a severe variant of DC in which an early onset of bone marrow failure leading to combined immunodeficiency is associated with microcephaly, cerebellar hypoplasia, and growth retardation. OBJECTIVES: Limited information is available on the cellular and molecular phenotypes of cells from patients with HH. We analyzed fibroblasts and whole blood cells from 5 patients with HH, 3 of them of unknown molecular origin. METHODS: Telomere length, cellular senescence rate, telomerase activity, telomeric aberration, and DNA repair pathways were investigated. RESULTS: Although patients' cells exhibit dysfunctional telomeres, sharp differences in the telomeric aberrations and telomere lengths were noted among these patients. In some patients the dysfunctional telomere phenotype was unprecedented and associated with either normal telomere length or with telomeric aberrations akin to fragile telomeres. This result is of particular importance because the molecular diagnosis of these patients is primarily based on telomere length, which therefore misses a subset of patients with telomere dysfunction. CONCLUSION: These observations provide the notions that (1) various telomere defects can lead to similar clinical features, (2) telomere dysfunction in cells from patients with DC/HH is not always associated with short telomeres, and (3) additional factors, likely involved in telomere protection rather than in length regulation, are responsible for a subset of DC/HH.

Myelodysplasia and leukemia of Fanconi anemia are associated with a specific pattern of genomic abnormalities that includes cryptic RUNX1/AML1 lesions.

Fanconi anemia (FA) is a genetic condition associated with bone marrow (BM) failure, myelodysplasia (MDS), and acute myeloid leukemia (AML). We studied 57 FA patients with hypoplastic or aplastic anemia (n = 20), MDS (n = 18), AML (n = 11), or no BM abnormality (n = 8). BM samples were analyzed by karyotype, high-density DNA arrays with respect to paired fibroblasts, and by selected oncogene sequencing. A specific pattern of chromosomal abnormalities was found in MDS/AML, which included 1q+ (44.8%), 3q+ (41.4%), -7/7q (17.2%), and 11q- (13.8%). Moreover, cryptic RUNX1/AML1 lesions (translocations, deletions, or mutations) were observed for the first time in FA (20.7%). Rare mutations of NRAS, FLT3-ITD, MLL-PTD, ERG amplification, and ZFP36L2-PRDM16 translocation, but no TP53, TET2, CBL, NPM1, and CEBPα mutations were found. Frequent homozygosity regions were related not to somatic copy-neutral loss of heterozygosity but to consanguinity, suggesting that homologous recombination is not a common progression mechanism in FA. Importantly, the RUNX1 and other chromosomal/genomic lesions were found at the MDS/AML stages, except for 1q+, which was found at all stages. These data have implications for staging and therapeutic managing in FA patients, and also to analyze the mechanisms of clonal evolution and oncogenesis in a background of genomic instability and BM failure.

Spontaneous abrogation of the G2DNA damage checkpoint has clinical benefits but promotes leukemogenesis in Fanconi anemia patients.

DNA damage checkpoints in the cell cycle may be important barriers against cancer progression in human cells. Fanconi anemia (FA) is an inherited DNA instability disorder that is associated with bone marrow failure and a strong predisposition to cancer. Although FA cells experience constitutive chromosomal breaks, cell cycle arrest at the G2 DNA damage checkpoint, and an excess of cell death, some patients do become clinically stable, and the mechanisms underlying this, other than spontaneous reversion of the disease-causing mutation, are not well understood. Here we have defined a clonal phenotype, termed attenuation, in which FA patients acquire an abrogation of the G2 checkpoint arrest. Attenuated cells expressed lower levels of CHK1 (also known as CHEK1) and p53. The attenuation could be recapitulated by modulating the ATR/CHK1 pathway, and CHK1 inhibition protected FA cells from cell death. FA patients who expressed the attenuated phenotype had mild bone marrow deficiency and reached adulthood, but several of them eventually developed myelodysplasia or leukemia. Better understanding of attenuation might help predict a patient's clinical course and guide choice of treatment. Our results also highlight the importance of evaluating the cellular DNA damage checkpoint and repair pathways in cancer therapies in general.

Metronidazole effects on microbiota and mucus layer thickness in the rat gut.

Both mucus and mucosa-associated bacteria form a specific environment in the gut; their disruption may play a crucial role in the development of intestinal bowel disease (IBD). Metronidazole, an antibiotic used in the treatment of IBD, alters gut microbiota and reduces basal oxidative stress to proteins in colonic tissue of healthy rats. The aim of this study was to evaluate the impact of the altered microbiota due to the metronidazole on the thickness of the mucus layer. This study was performed in healthy untreated rats (control group) or rats treated by metronidazole (metronidazole-treated rats, 1 mg mL(-1) in drinking water for 7 days). Both PCR-temporal temperature gradient gel electrophoresis and quantitative PCR (qPCR) revealed an altered microbiota with an increase in bifidobacteria and enterobacteria in metronidazole-treated rats compared with control rats. Moreover, a dominant bifidobacterial species, Bifidobacterium pseudolongum, was detected. Using qPCR and FISH, we showed that bifidobacteria were also increased in the microbiota-associated mucosa. At the same time, the mucus layer thickness was increased approximately twofold. These results could explain the benefits of metronidazole treatment and warrant further investigations to define the role of bifidobacteria in the colonic mucosa.

Crypt abscess-associated microbiota in inflammatory bowel disease and acute self-limited colitis.

AIM: To evaluate whether crypt abscesses from inflammatory bowel disease (IBD) patients contain bacteria and to establish their nature. METHODS: We studied 17 ulcerative colitis patients, 11 Crohn's disease patients, 7 patients with acute self-limited colitis (ASLC) and normal colonic biopsies from 5 subjects who underwent colonoscopy for colon cancer screening. A fluorescent in situ hybridization technique was applied to colonic biopsies to assess the microbiota composition of the crypts and crypt abscesses. RESULTS: Crypts colonized by bacteria were observed in 42.9% and 3.6% of ASLC and IBD patients, respectively (P = 0.019). Crypt abscesses colonized by bacteria were observed in 28.6% and 0.0% of ASLC and IBD patients, respectively (P = 0.035). CONCLUSION: These results do not support the hypothesis that crypt abscesses in IBD are the result of localized dysbiosis arising from persistence of living bacteria colonizing the crypts.