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1.
Sci Rep ; 10(1): 6997, 2020 04 24.
Artigo em Inglês | MEDLINE | ID: mdl-32332829

RESUMO

The promising ability to genetically modify hematopoietic stem and progenitor cells by precise gene editing remains challenging due to their sensitivity to in vitro manipulations and poor efficiencies of homologous recombination. This study represents the first evidence of implementing a gene editing strategy in a murine safe harbor locus site that phenotypically corrects primary cells from a mouse model of Fanconi anemia A. By means of the co-delivery of transcription activator-like effector nucleases and a donor therapeutic FANCA template to the Mbs85 locus, we achieved efficient gene targeting (23%) in mFA-A fibroblasts. This resulted in the phenotypic correction of these cells, as revealed by the reduced sensitivity of these cells to mitomycin C. Moreover, robust evidence of targeted integration was observed in murine wild type and FA-A hematopoietic progenitor cells, reaching mean targeted integration values of 21% and 16% respectively, that were associated with the phenotypic correction of these cells. Overall, our results demonstrate the feasibility of implementing a therapeutic targeted integration strategy into the mMbs85 locus, ortholog to the well-validated hAAVS1, constituting the first study of gene editing in mHSC with TALEN, that sets the basis for the use of a new safe harbor locus in mice.

2.
J Med Genet ; 57(4): 258-268, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31586946

RESUMO

PURPOSE: Patients with Fanconi anaemia (FA), a rare DNA repair genetic disease, exhibit chromosome fragility, bone marrow failure, malformations and cancer susceptibility. FA molecular diagnosis is challenging since FA is caused by point mutations and large deletions in 22 genes following three heritability patterns. To optimise FA patients' characterisation, we developed a simplified but effective methodology based on whole exome sequencing (WES) and functional studies. METHODS: 68 patients with FA were analysed by commercial WES services. Copy number variations were evaluated by sequencing data analysis with RStudio. To test FANCA missense variants, wt FANCA cDNA was cloned and variants were introduced by site-directed mutagenesis. Vectors were then tested for their ability to complement DNA repair defects of a FANCA-KO human cell line generated by TALEN technologies. RESULTS: We identified 93.3% of mutated alleles including large deletions. We determined the pathogenicity of three FANCA missense variants and demonstrated that two FANCA variants reported in mutations databases as 'affecting functions' are SNPs. Deep analysis of sequencing data revealed patients' true mutations, highlighting the importance of functional analysis. In one patient, no pathogenic variant could be identified in any of the 22 known FA genes, and in seven patients, only one deleterious variant could be identified (three patients each with FANCA and FANCD2 and one patient with FANCE mutations) CONCLUSION: WES and proper bioinformatics analysis are sufficient to effectively characterise patients with FA regardless of the rarity of their complementation group, type of mutations, mosaic condition and DNA source.

3.
NPJ Breast Cancer ; 5: 38, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31700994

RESUMO

Breast cancer is a common disease partially caused by genetic risk factors. Germline pathogenic variants in DNA repair genes BRCA1, BRCA2, PALB2, ATM, and CHEK2 are associated with breast cancer risk. FANCM, which encodes for a DNA translocase, has been proposed as a breast cancer predisposition gene, with greater effects for the ER-negative and triple-negative breast cancer (TNBC) subtypes. We tested the three recurrent protein-truncating variants FANCM:p.Arg658*, p.Gln1701*, and p.Arg1931* for association with breast cancer risk in 67,112 cases, 53,766 controls, and 26,662 carriers of pathogenic variants of BRCA1 or BRCA2. These three variants were also studied functionally by measuring survival and chromosome fragility in FANCM -/- patient-derived immortalized fibroblasts treated with diepoxybutane or olaparib. We observed that FANCM:p.Arg658* was associated with increased risk of ER-negative disease and TNBC (OR = 2.44, P = 0.034 and OR = 3.79; P = 0.009, respectively). In a country-restricted analysis, we confirmed the associations detected for FANCM:p.Arg658* and found that also FANCM:p.Arg1931* was associated with ER-negative breast cancer risk (OR = 1.96; P = 0.006). The functional results indicated that all three variants were deleterious affecting cell survival and chromosome stability with FANCM:p.Arg658* causing more severe phenotypes. In conclusion, we confirmed that the two rare FANCM deleterious variants p.Arg658* and p.Arg1931* are risk factors for ER-negative and TNBC subtypes. Overall our data suggest that the effect of truncating variants on breast cancer risk may depend on their position in the gene. Cell sensitivity to olaparib exposure, identifies a possible therapeutic option to treat FANCM-associated tumors.

4.
Nat Med ; 25(9): 1396-1401, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31501599

RESUMO

Fanconi anemia (FA) is a DNA repair syndrome generated by mutations in any of the 22 FA genes discovered to date1,2. Mutations in FANCA account for more than 60% of FA cases worldwide3,4. Clinically, FA is associated with congenital abnormalities and cancer predisposition. However, bone marrow failure is the primary pathological feature of FA that becomes evident in 70-80% of patients with FA during the first decade of life5,6. In this clinical study (ClinicalTrials.gov, NCT03157804 ; European Clinical Trials Database, 2011-006100-12), we demonstrate that lentiviral-mediated hematopoietic gene therapy reproducibly confers engraftment and proliferation advantages of gene-corrected hematopoietic stem cells (HSCs) in non-conditioned patients with FA subtype A. Insertion-site analyses revealed the multipotent nature of corrected HSCs and showed that the repopulation advantage of these cells was not due to genotoxic integrations of the therapeutic provirus. Phenotypic correction of blood and bone marrow cells was shown by the acquired resistance of hematopoietic progenitors and T lymphocytes to DNA cross-linking agents. Additionally, an arrest of bone marrow failure progression was observed in patients with the highest levels of gene marking. The progressive engraftment of corrected HSCs in non-conditioned patients with FA supports that gene therapy should constitute an innovative low-toxicity therapeutic option for this life-threatening disorder.


Assuntos
Proteína do Grupo de Complementação A da Anemia de Fanconi/genética , Anemia de Fanconi/terapia , Terapia Genética , Transplante de Células-Tronco Hematopoéticas , Adolescente , Adulto , Células da Medula Óssea/citologia , Criança , Pré-Escolar , Anemia de Fanconi/genética , Anemia de Fanconi/fisiopatologia , Feminino , Vetores Genéticos/genética , Células-Tronco Hematopoéticas/metabolismo , Humanos , Lactente , Lentivirus/genética , Masculino , Mutação/genética , Espanha/epidemiologia , Reparo Gênico Alvo-Dirigido , Transdução Genética , Adulto Jovem
5.
Mol Genet Genomic Med ; 7(9): e863, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31347298

RESUMO

BACKGROUND: Biallelic BRCA1 mutations are regarded either embryonically lethal or to cause Fanconi anemia (FA), a genomic instability syndrome characterized by bone marrow failure, developmental abnormalities, and cancer predisposition. We report biallelic BRCA1 mutations c.181T > G (p.Cys61Gly) and c.5096G > A (p.Arg1699Gln) in a woman with breast cancer diagnosed at the age of 30 years. The common European founder mutation p.Cys61Gly confers high cancer risk, whereas the deleterious p.Arg1699Gln is hypomorphic and was suggested to confer intermediate cancer risk. METHODS AND RESULTS: Aside from significant toxicity from chemotherapy, the patient showed mild FA-like features (e.g., short stature, microcephaly, skin hyperpigmentation). Chromosome fragility, a hallmark of FA patient cells, was not present in patient-derived peripheral blood lymphocytes. We demonstrated that the p.Arg1699Gln mutation impairs DNA double-strand break repair, elevates RAD51 foci levels at baseline, and compromises BRCA1 protein function in protecting from replication stress. Although the p.Arg1699Gln mutation compromises BRCA1 function, the residual activity of the p.Arg1699Gln allele likely prevents from chromosome fragility and a more severe FA phenotype. CONCLUSION: Our data expand the clinical spectrum associated with biallelic BRCA1 mutations, ranging from embryonic lethality to a mild FA-like phenotype and no chromosome fragility.


Assuntos
Proteína BRCA1/genética , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/genética , Fragilidade Cromossômica , Anemia de Fanconi/diagnóstico , Anemia de Fanconi/genética , Mutação em Linhagem Germinativa , Fenótipo , Idade de Início , Alelos , Análise Mutacional de DNA , Feminino , Imunofluorescência , Predisposição Genética para Doença , Genótipo , Histonas , Humanos , Mutação , Linhagem , Rad51 Recombinase/genética
6.
Genet Med ; 21(1): 189-194, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29904161

RESUMO

PURPOSE: In about 10% of patients affected by Fanconi anemia (FA) the diagnosis is delayed until adulthood, and the presenting symptom in these "occult" FA cases is often a solid cancer and cancer treatment-related toxicity. Highly predictive clinical parameter(s) for diagnosing such an adult-onset cases are missing. METHODS: (1) Exome sequencing (ES), (2) Sanger sequencing of FANCA, (3) diepoxybutane (DEB)-induced chromosome breakage test. RESULTS: ES identified a pathogenic homozygous FANCA variant in a patient affected by Sertoli cell-only syndrome (SCOS) and in his azoospermic brother. Although they had no overt anemia, chromosomal breakage test revealed a reverse somatic mosaicism in the former and a typical FA picture in the latter. In 27 selected SCOS cases, 1 additional patient showing compound heterozygous pathogenic FANCA variants was identified with positive chromosomal breakage test. CONCLUSION: We report an extraordinarily high frequency of FA in a specific subgroup of azoospermic patients (7.1%). The screening for FANCA pathogenic variants in such patients has the potential to identify undiagnosed FA before the appearance of other severe clinical manifestations of the disease. The definition of this high-risk group for "occult" FA, based on specific testis phenotype with mild/borderline hematological alterations, is of unforeseen clinical relevance.


Assuntos
Azoospermia/genética , Proteína do Grupo de Complementação A da Anemia de Fanconi/genética , Anemia de Fanconi/genética , Síndrome de Células de Sertoli/genética , Adulto , Idade de Início , Azoospermia/sangue , Azoospermia/complicações , Azoospermia/patologia , Quebra Cromossômica , Exoma/genética , Anemia de Fanconi/sangue , Anemia de Fanconi/diagnóstico , Anemia de Fanconi/patologia , Feminino , Regulação da Expressão Gênica/genética , Humanos , Masculino , Mutação , Linhagem , Fenótipo , Síndrome de Células de Sertoli/sangue , Síndrome de Células de Sertoli/complicações , Síndrome de Células de Sertoli/patologia , Testículo/metabolismo , Testículo/patologia , Sequenciamento Completo do Exoma
8.
Am J Hum Genet ; 103(2): 221-231, 2018 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-30057030

RESUMO

Bloom syndrome, caused by biallelic mutations in BLM, is characterized by prenatal-onset growth deficiency, short stature, an erythematous photosensitive malar rash, and increased cancer predisposition. Diagnostically, a hallmark feature is the presence of increased sister chromatid exchanges (SCEs) on cytogenetic testing. Here, we describe biallelic mutations in TOP3A in ten individuals with prenatal-onset growth restriction and microcephaly. TOP3A encodes topoisomerase III alpha (TopIIIα), which binds to BLM as part of the BTRR complex, and promotes dissolution of double Holliday junctions arising during homologous recombination. We also identify a homozygous truncating variant in RMI1, which encodes another component of the BTRR complex, in two individuals with microcephalic dwarfism. The TOP3A mutations substantially reduce cellular levels of TopIIIα, and consequently subjects' cells demonstrate elevated rates of SCE. Unresolved DNA recombination and/or replication intermediates persist into mitosis, leading to chromosome segregation defects and genome instability that most likely explain the growth restriction seen in these subjects and in Bloom syndrome. Clinical features of mitochondrial dysfunction are evident in several individuals with biallelic TOP3A mutations, consistent with the recently reported additional function of TopIIIα in mitochondrial DNA decatenation. In summary, our findings establish TOP3A mutations as an additional cause of prenatal-onset short stature with increased cytogenetic SCEs and implicate the decatenation activity of the BTRR complex in their pathogenesis.

9.
Nat Commun ; 9(1): 967, 2018 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-29511213

RESUMO

BRCA1 is a tumor suppressor that regulates DNA repair by homologous recombination. Germline mutations in BRCA1 are associated with increased risk of breast and ovarian cancer and BRCA1 deficient tumors are exquisitely sensitive to poly (ADP-ribose) polymerase (PARP) inhibitors. Therefore, uncovering additional components of this DNA repair pathway is of extreme importance for further understanding cancer development and therapeutic vulnerabilities. Here, we identify EDC4, a known component of processing-bodies and regulator of mRNA decapping, as a member of the BRCA1-BRIP1-TOPBP1 complex. EDC4 plays a key role in homologous recombination by stimulating end resection at double-strand breaks. EDC4 deficiency leads to genome instability and hypersensitivity to DNA interstrand cross-linking drugs and PARP inhibitors. Lack-of-function mutations in EDC4 were detected in BRCA1/2-mutation-negative breast cancer cases, suggesting a role in breast cancer susceptibility. Collectively, this study recognizes EDC4 with a dual role in decapping and DNA repair whose inactivation phenocopies BRCA1 deficiency.


Assuntos
Proteína BRCA1/metabolismo , Neoplasias da Mama/metabolismo , Reparo do DNA , Proteínas/metabolismo , Proteína BRCA1/genética , Neoplasias da Mama/genética , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Feminino , Recombinação Homóloga , Humanos , Mutação , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Poli(ADP-Ribose) Polimerase-1/genética , Poli(ADP-Ribose) Polimerase-1/metabolismo , Ligação Proteica , Proteínas/genética , Capuzes de RNA/genética , Capuzes de RNA/metabolismo
10.
Genet Med ; 20(4): 458-463, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-28837157

RESUMO

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.


Assuntos
Alelos , DNA Helicases/genética , Anemia de Fanconi/genética , Predisposição Genética para Doença , Neoplasias/diagnóstico , Neoplasias/genética , Deleção de Sequência , Adolescente , Linhagem Celular , Fragilidade Cromossômica/efeitos dos fármacos , DNA Helicases/metabolismo , Feminino , Estudos de Associação Genética , Teste de Complementação Genética , Homozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , Fenótipo
11.
Genet Med ; 20(4): 452-457, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-28837162

RESUMO

PurposeMonoallelic germ-line mutations in the BRCA1/FANCS, BRCA2/FANCD1 and PALB2/FANCN genes confer high risk of breast cancer. Biallelic mutations in these genes cause Fanconi anemia (FA), characterized by malformations, bone marrow failure, chromosome fragility, and cancer predisposition (BRCA2/FANCD1 and PALB2/FANCN), or an FA-like disease presenting a phenotype similar to FA but without bone marrow failure (BRCA1/FANCS). FANCM monoallelic mutations have been reported as moderate risk factors for breast cancer, but there are no reports of any clinical phenotype observed in carriers of biallelic mutations.MethodsBreast cancer probands were subjected to mutation analysis by sequencing gene panels or testing DNA damage response genes.ResultsFive cases homozygous for FANCM loss-of-function mutations were identified. They show a heterogeneous phenotype including cancer predisposition, toxicity to chemotherapy, early menopause, and possibly chromosome fragility. Phenotype severity might correlate with mutation position in the gene.ConclusionOur data indicate that biallelic FANCM mutations do not cause classical FA, providing proof that FANCM is not a canonical FA gene. Moreover, our observations support previous findings suggesting that FANCM is a breast cancer-predisposing gene. Mutation testing of FANCM might be considered for individuals with the above-described clinical features.


Assuntos
Alelos , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/genética , Fragilidade Cromossômica , DNA Helicases/genética , Anemia de Fanconi/diagnóstico , Anemia de Fanconi/genética , Predisposição Genética para Doença , Mutação , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Consanguinidade , Resistencia a Medicamentos Antineoplásicos/genética , Feminino , Estudos de Associação Genética , Genótipo , Mutação em Linhagem Germinativa , Humanos , Masculino , Linhagem , Fenótipo , Medição de Risco , Fatores de Risco
12.
Blood Adv ; 1(5): 319-329, 2017 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-29296947

RESUMO

Detectable clonal mosaicism for large chromosomal events has been associated with aging and an increased risk of hematological and some solid cancers. We hypothesized that genetic cancer predisposition disorders, such as Fanconi anemia (FA), could manifest a high rate of chromosomal mosaic events (CMEs) in peripheral blood, which could be used as early biomarkers of cancer risk. We studied the prevalence of CMEs by single-nucleotide polymorphism (SNP) array in 130 FA patients' blood DNA and their impact on cancer risk. We detected 51 CMEs (4.4-159 Mb in size) in 16 out of 130 patients (12.3%), of which 9 had multiple CMEs. The most frequent events were gains at 3q (n = 6) and 1q (n = 5), both previously associated with leukemia, as well as rearrangements with breakpoint clustering within the major histocompatibility complex locus (P = 7.3 × 10-9). Compared with 15 743 age-matched population controls, FA patients had a 126 to 140 times higher risk of detectable CMEs in blood (P < 2.2 × 10-16). Prevalent and incident hematologic and solid cancers were more common in CME carriers (odds ratio [OR] = 11.6, 95% confidence interval [CI] = 3.4-39.3, P = 2.8 × 10-5), leading to poorer prognosis. The age-adjusted hazard risk (HR) of having cancer was almost 5 times higher in FA individuals with CMEs than in those without CMEs. Regarding survival, the HR of dying was 4 times higher in FA individuals having CMEs (HR = 4.0, 95% CI = 2.0-7.9, P = 5.7 × 10-5). Therefore, our data suggest that molecular karyotyping with SNP arrays in easy-to-obtain blood samples could be used for better monitoring of bone marrow clonal events, cancer risk, and overall survival of FA patients.

13.
Hum Mutat ; 34(12): 1615-8, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24027083

RESUMO

Recently, it has been reported that biallelic mutations in the ERCC4 (FANCQ) gene cause Fanconi anemia (FA) subtype FA-Q. To investigate the possible role of ERCC4 in breast and ovarian cancer susceptibility, as occurs with other FA genes, we screened the 11 coding exons and exon-intron boundaries of ERCC4 in 1573 index cases from high-risk Spanish familial breast and ovarian cancer pedigrees that had been tested negative for BRCA1 and BRCA2 mutations and 854 controls. The frequency of ERCC4 mutation carriers does not differ between cases and controls, suggesting that ERCC4 is not a cancer susceptibility gene. Interestingly, the prevalence of ERCC4 mutation carriers (one in 288) is similar to that reported for FANCA, whereas there are approximately 100-fold more FA-A than FA-Q patients, indicating that most biallelic combinations of ERCC4 mutations are embryo lethal. Finally, we identified additional bone-fide FA ERCC4 mutations specifically disrupting interstrand cross-link repair.


Assuntos
Alelos , Neoplasias da Mama/congênito , Proteínas de Ligação a DNA/genética , Predisposição Genética para Doença , Variação Genética , Neoplasias Ovarianas/genética , Substituição de Aminoácidos , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Estudos de Casos e Controles , Proteínas de Ligação a DNA/metabolismo , Éxons , Feminino , Síndrome Hereditária de Câncer de Mama e Ovário , Heterozigoto , Humanos , Mutação , Neoplasias Ovarianas/metabolismo , Fenótipo , Espanha
14.
Am J Hum Genet ; 92(5): 800-6, 2013 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-23623386

RESUMO

Fanconi anemia (FA) is a rare genomic instability disorder characterized by progressive bone marrow failure and predisposition to cancer. FA-associated gene products are involved in the repair of DNA interstrand crosslinks (ICLs). Fifteen FA-associated genes have been identified, but the genetic basis in some individuals still remains unresolved. Here, we used whole-exome and Sanger sequencing on DNA of unclassified FA individuals and discovered biallelic germline mutations in ERCC4 (XPF), a structure-specific nuclease-encoding gene previously connected to xeroderma pigmentosum and segmental XFE progeroid syndrome. Genetic reversion and wild-type ERCC4 cDNA complemented the phenotype of the FA cell lines, providing genetic evidence that mutations in ERCC4 cause this FA subtype. Further biochemical and functional analysis demonstrated that the identified FA-causing ERCC4 mutations strongly disrupt the function of XPF in DNA ICL repair without severely compromising nucleotide excision repair. Our data show that depending on the type of ERCC4 mutation and the resulting balance between both DNA repair activities, individuals present with one of the three clinically distinct disorders, highlighting the multifunctional nature of the XPF endonuclease in genome stability and human disease.


Assuntos
Proteínas de Ligação a DNA/genética , Desoxirribonucleases/genética , Anemia de Fanconi/genética , Predisposição Genética para Doença/genética , Fenótipo , Apoptose/genética , Apoptose/efeitos da radiação , Sequência de Bases , Exoma/genética , Anemia de Fanconi/patologia , Mutação em Linhagem Germinativa/genética , Humanos , Immunoblotting , Imunoprecipitação , Dados de Sequência Molecular , Análise de Sequência de DNA , Raios Ultravioleta
15.
Blood ; 120(1): 86-9, 2012 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-22611161

RESUMO

Fanconi anemia (FA) is a rare bone marrow failure disorder with defective DNA interstrand crosslink repair. Still, there are FA patients without mutations in any of the 15 genes individually underlying the disease. A candidate protein for those patients, FA nuclease 1 (FAN1), whose gene is located at chromosome 15q13.3, is recruited to stalled replication forks by binding to monoubiquitinated FANCD2 and is required for interstrand crosslink repair, suggesting that mutation of FAN1 may cause FA. Here we studied clinical, cellular, and genetic features in 4 patients carrying a homozygous 15q13.3 micro-deletion, including FAN1 and 6 additional genes. Biallelic deletion of the entire FAN1 gene was confirmed by failure of 3'- and 5'-PCR amplification. Western blot analysis failed to show FAN1 protein in the patients' cell lines. Chromosome fragility was normal in all 4 FAN1-deficient patients, although their cells showed mild sensitivity to mitomycin C in terms of cell survival and G(2) phase arrest, dissimilar in degree to FA cells. Clinically, there were no symptoms pointing the way to FA. Our results suggest that FAN1 has a minor role in interstrand crosslink repair compared with true FA genes and exclude FAN1 as a novel FA gene.


Assuntos
Reparo do DNA/fisiologia , Exodesoxirribonucleases/genética , Exodesoxirribonucleases/fisiologia , Anemia de Fanconi/genética , Anemia de Fanconi/fisiopatologia , Sobrevivência Celular/fisiologia , Células Cultivadas , Criança , Pré-Escolar , Cromossomos Humanos Par 15 , Replicação do DNA/fisiologia , Endodesoxirribonucleases , Anemia de Fanconi/patologia , Deleção de Genes , Homozigoto , Humanos , Lactente , Enzimas Multifuncionais
16.
Blood ; 117(14): 3759-69, 2011 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-21273304

RESUMO

Fanconi anemia is characterized by congenital abnormalities, bone marrow failure, and cancer predisposition. To investigate the origin, functional role, and clinical impact of FANCA mutations, we determined a FANCA mutational spectrum with 130 pathogenic alleles. Some of these mutations were further characterized for their distribution in populations, mode of emergence, or functional consequences at cellular and clinical level. The world most frequent FANCA mutation is not the result of a mutational "hot-spot" but results from worldwide dissemination of an ancestral Indo-European mutation. We provide molecular evidence that total absence of FANCA in humans does not reduce embryonic viability, as the observed frequency of mutation carriers in the Gypsy population equals the expected by Hardy-Weinberg equilibrium. We also prove that long distance Alu-Alu recombination can cause Fanconi anemia by originating large interstitial deletions involving FANCA and 2 adjacent genes. Finally, we show that all missense mutations studied lead to an altered FANCA protein that is unable to relocate to the nucleus and activate the FA/BRCA pathway. This may explain the observed lack of correlation between type of FANCA mutation and cellular phenotype or clinical severity in terms of age of onset of hematologic disease or number of malformations.


Assuntos
Proteína do Grupo de Complementação A da Anemia de Fanconi/genética , Proteína do Grupo de Complementação A da Anemia de Fanconi/fisiologia , Anemia de Fanconi/genética , Anemia de Fanconi/patologia , Mutação , Adolescente , Idade de Início , Sequência de Bases , Técnicas de Cultura de Células , Células Cultivadas , Criança , Pré-Escolar , Aberrações Cromossômicas , Hibridização Genômica Comparativa , Análise Mutacional de DNA , Anemia de Fanconi/diagnóstico , Anemia de Fanconi/epidemiologia , Proteína do Grupo de Complementação A da Anemia de Fanconi/metabolismo , Frequência do Gene , Humanos , Lactente , Modelos Biológicos , Dados de Sequência Molecular , Mutação/fisiologia , Fenótipo , Espanha/epidemiologia
17.
J Med Genet ; 48(4): 242-50, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21217111

RESUMO

BACKGROUND: Fanconi anaemia (FA) is a rare syndrome characterized by bone marrow failure, malformations and cancer predisposition. Chromosome fragility induced by DNA interstrand crosslink (ICL)-inducing agents such as diepoxybutane (DEB) or mitomycin C (MMC) is the 'gold standard' test for the diagnosis of FA. OBJECTIVE: To study the variability, the diagnostic implications and the clinical impact of chromosome fragility in FA. METHODS: Data are presented from 198 DEB-induced chromosome fragility tests in patients with and without FA where information on genetic subtype, cell sensitivity to MMC and clinical data were available. RESULTS: This large series allowed quantification of the variability and the level of overlap in ICL sensitivity among patients with FA and the normal population. A new chromosome fragility index is proposed that provides a cut-off diagnostic level to unambiguously distinguish patients with FA, including mosaics, from non-FA individuals. Spontaneous chromosome fragility and its correlation with DEB-induced fragility was also analysed, indicating that although both variables are correlated, 54% of patients with FA do not have spontaneous fragility. The data reveal a correlation between malformations and sensitivity to ICL-inducing agents. This correlation was also statistically significant when the analysis was restricted to patients from the FA-A complementation group. Finally, chromosome fragility does not correlate with the age of onset of haematological disease. CONCLUSIONS: This study proposes a new chromosome fragility index and suggests that genome instability during embryo development may be related to malformations in FA, while DEB-induced chromosome breaks in T cells have no prognostic value for the haematological disease.


Assuntos
Fragilidade Cromossômica , Anemia de Fanconi/genética , Reagentes para Ligações Cruzadas/farmacologia , Compostos de Epóxi/farmacologia , Anemia de Fanconi/diagnóstico , Humanos , Mitomicina/farmacologia , Mosaicismo , Fenótipo
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