An unusual ocular manifestation in Fanconi anemia: congenital glaucoma

Fanconi anemia is an autosomal recessive disorder characterized by growth retardation along with many congenital abnormalities involving the eyes. We report herein two siblings with Fanconi anemia who also have bilateral congenital glaucoma. To the best of our knowledge, this is the first report of congenital glaucoma in patients with Fanconi anemia.     

Five Fanconi anemia patients with unusual organ pathologies

Fanconi anemia (FA) is a rare autosomal recessive disorder that presents with variable organ abnormalities, progressive cytopenia, and susceptibility to the development of several malignancies. Although some of the organ pathologies such as microcephaly, microphthalmia, skin dyspigmentation, urogenital system involvement, and radial ray skeletal abnormalities are relatively common, there are some other abnormalities that are rarely associated with the disease [Alter BP. In: Nathan DG, Oski FA, editors. Hematology of infancy and childhood. Philadelphia: Saunders; 2003. p 259-273]. In this paper, five cases of unrelated FA patients with unusual organ pathologies, including chronic obstructive lung disease, lipodystrophy, Sprengel's deformity, diaphragmatic hernia, and inflammatory linear verrucous epidermal nevus (ILVEN) are presented. Recognition of unusual pathologies associated with FA is important in order to improve our understanding of the relationship between the disease and presenting organ pathologies.     

Clonal chromosome abnormalities in Fanconi anemia

Fanconi anemia (FA) belongs to the chromosomal instability syndromes and frequently evolves toward hematopoietic malignancy. While the recent isolation of one of the genes of FA allows to view to gene therapy, the best treatment is currently bone marrow transplantation. In this review, the data on clonal chromosome abnormalities of FA patients are presented and their significance discussed in the context of the disease.     

Molecular Pathogenesis of Fanconi Anemia

Fanconi anemia (FA) is a rare autosomal recessive chromosomal breakage disorder characterized by the childhood onset of aplastic anemia, developmental defects, cancer susceptibility, and cellular hypersensitivity to DNA-cross-linking agents. FA patients can be divided into at least 8 complementation groups (FA-A, FA-B, FA-C, FA-D1, FA-D2, FA-E, FA-F, and FA-G). FA proteins encoded by 6 cloned FA genes (FANCA, FANCC, FANCD2, FANCE, FANCF, and FANCG) cooperate in a common pathway, culminating in the monoubiquitination of FANCD2 protein and colocalization of FANCD2 and BRCA1 proteins in nuclear foci. These BRCA1 foci have been implicated in the process of homologous recombination-mediated DNA repair. In this review, we will summarize the current progress in the field of FA research and highlight some of the potential functions of the FA pathway in DNA-damage response.     

Fertility recovery and pregnancy after allogeneic hematopoietic stem cell transplantation in Fanconi anemia patients

Reduced fertility is one clinical manifestation among other well known Fanconi anemia features. Most recipients of allogeneic hematopoietic stem cell transplantation suffer from secondary infertility owing to gonadal damage from myeloablative conditioning. In order to evaluate the rate of pregnancy in Fanconi anemia transplanted patients, we performed a retrospective analysis of female patients transplanted in 15 centers from 1976 to 2008. Among 578 transplanted Fanconi anemia patients, we identified 285 transplanted females of whom 101 patients were aged 16 years or over. Ten became pregnant (4 twice). Before hematopoietic stem cell transplantation all had confirmed Fanconi anemia diagnosis. Median age at transplantation was 12 years (range 5–17 years). Conditioning regimen consisted of cyclophosphamide with or without irradiation. During follow up, 5 of 10 patients presented signs of ovarian failure. Among those, 2 patients spontaneously recovered regular menses, and 3 received hormonal replacement therapy. Pregnancy occurred from four to 17 years after hematopoietic stem cell transplantation. Three patients had preterm deliveries, one patient had a hysterectomy for bleeding. All 14 newborns had normal growth and development without congenital diseases. In conclusion, recovery of normal ovarian function and a viable pregnancy is a realistic but relatively rare possibility even in Fanconi anemia patients following hematopoietic stem cell transplantation. Mechanisms of fertility recovery are discussed.     

Coinheritance of BRCA1 and BRCA2 mutations with Fanconi anemia and Bloom syndrome mutations in Ashkenazi Jewish population: possible role in risk modification for cancer development

Fanconi anemia (FA) and Bloom syndrome (BS) are rare autosomal recessive genetic disorders manifesting in childhood, with a predisposition to cancer development in adolescence and adulthood. Both syndromes are relatively prevalent among the Ashkenazi Jewish population, and, in both syndromes, mutations specific to this population have been identified. Similarly, unique Ashkenazi mutations were found in the genes BRCA1 and BRCA2. These two genes, when mutated, play important roles in familial breast and ovarian carcinogenesis. The genes involved in the pathogenesis of the FA and BS belong to the general class of instability genes. Heterozygosity for the FA gene has no known promalignant potential, while the BS mutation carrier state was associated with an increased frequency of colorectal cancer. The especially frequent carrier state among the Ashkenazi Jewish population coupled with the high prevalence of BRCA1 and BRCA2 in the same population has led us to search for coinheritance affecting the potential for cancer development. One hundred Ashkenazi women with known BRCA1 and BRCA2 mutations were screened for the FA mutation IVS4+4 A-->T and the BS mutation blm(Ash). Our results indicate that there is an increased prevalence of both FA and BS mutation carriers among the population studied compared with the general Ashkenazi population (prevalence of FA mutation 4/100 women [4%] as compared to 35/3104 previously published controls [1.1%], P=0.031, and for BS mutation 3/100 [3.2%] as compared to 36/4001 [0.9%], P=0.058). There was no statistically significant effect of the coinheritance on cancer prevalence, type of cancer, or age of cancer onset. Coinheritance of FA and/or BS mutations seems to be more prevalent among BRCA mutation carriers, but a larger study encompassing more women may help in clarifying this issue.     

Role of gene therapy in Fanconi anemia: A systematic and literature review with future directions

Gene therapy (GT) has been reported to improve bone marrow function in individuals with Fanconi anemia (FA); however, its clinical application is still in the initial stages. We conducted this systematic review, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, to assess the long-term safety and clinical outcomes of GT in FA patients. Electronic searches from PubMed, Web of Science, Cochrane Library, and Google Scholar were conducted and full texts of articles meeting our inclusion criteria were reviewed. Three clinical trials were included, with a total of nine patients and mean age of 10.7 ± 5.7 years. All patients had lentiviral-mediated GT. A 1-year follow-up showed stabilization in blood lineages, without any serious adverse effects from GT. A metaregression analysis could not be conducted, as very little long-term follow-up data of patients was observed, and the median survival rate could not be calculated. Thus, we can conclude that GT seems to be a safe procedure in FA; however, further research needs to be conducted on the longitudinal clinical effects of GT in FA, for a better insight into its potential to become a standard form of treatment.     

Fanconi anaemia group A (FANCA) mutations in Israeli non-Ashkenazi Jewish patients

Fanconi anaemia (FA) is a genetically heterogeneous disease with at least eight complementation groups (A-H). In the present study, we investigated the molecular basis of the disease in 13 unrelated Israeli Jewish (non-Ashkenazi) patients with FA. All 43 exons of the Fanconi anaemia A (FANCA) gene were amplified from genomic DNA and screened for mutations by single-strand conformation polymorphism and DNA sequencing. We identified four ethnic-specific mutations: (1) 2172-2173insG (exon 24), the first 'Moroccan mutation': (2) 4275delT (exon 43), the second 'Moroccan mutation'; (3) 890-893del (exon 10), the 'Tunisian mutation'; and (4) 2574C > G (S858R), the 'Indian mutation'. The tetranucleotide CCTG motif, previously identified as a mutation hotspot in FANCA and other human genes, was found in the vicinity of 2172-2173insG and 890-893del. According to our study, the four mutations account for the majority (88%) of the FANCA alleles in the Israeli Jewish (non-Ashkenazi) FA population. A screening of 300 Moroccan Jews identified three carriers of the first 'Moroccan mutation', but we did not find any carrier of the second 'Moroccan mutation' among 140 Moroccan Jews, nor any carrier of the 'Tunisian mutation' among 50 Tunisian Jews. Two 'Indian mutation' carriers were identified among 53 Indian Jews. All carriers within each ethnic group had the same haplotype, suggesting a common founder for each mutation.     

Successful umbilical cord blood transplantation for Fanconi anemia using preimplantation genetic diagnosis for HLA-matched donor

Fanconi anemia is a rare autosomal recessive disease characterized by bone marrow failure, developmental anomalies, and a high incidence of myelodysplasia and acute myeloid leukemia. Stem cell transplantation is the only curative treatment. In the absence of matched- sibling donor, an alternative mismatched family or matched unrelated donor can be used, but the results are inferior to the matched-sibling transplant and carry a high risk of morbidity and mortality. Preimplantation genetic diagnosis (PGD) has been increasingly used in recent years for mutation analysis for many genetic disorders and results in the birth of healthy children, saving the need for the termination of pregnancy of an affected embryo. The use of PGD for combined analysis of mutation and HLA-matching was reported for the first time in 2001. This enables the birth of an unaffected child who can serve as a donor for an affected sibling in need for stem cell transplantation. We report successful cord blood transplantation for a Fanconi anemia patient from his HLA-matched sibling, born after PGD that included mutation analysis for Fanconi anemia and HLA typing. PGD can provide an unaffected donor for a sibling affected by genetic disease in the absence of a compatible related donor.     

DNA interstrand cross‐link repair: understanding role of Fanconi anemia pathway and therapeutic implications

Interstrand cross‐links (ICLs) are extremely toxic DNA lesions that prevent DNA double‐helix separation due to the irreversible covalent linkage binding of some agents on DNA strands. Agents that induce these ICLs are thus widely used as chemotherapeutic drugs but may also lead to tumor growth. Fanconi anemia (FA) is a rare genetic disorder that leads to ICL sensitivity. This review provides update on current understanding of the role of FA proteins in repairing ICLs at various stages of cell cycle. We also discuss link between DNA cross‐link genotoxicity caused by aldehydes in FA pathway. Besides this, we summarize various ICL agents that act as drugs to treat different types of tumors and highlight strategies for modulating ICL sensitivity for therapeutic interventions that may be helpful in controlling cancer and life‐threatening disease, FA.     

SV40 T-antigen expression in skin fibroblasts from clinically normal individuals and from ten cases of Fanconi anemia.

Previous studies of the expression of SV40 genetic information by skin fibroblasts included limited numbers of cell donors and failed to adequately consider possible effects of age, sex, and ethnic origin on assay results. A population of 76 healthy subjects were selected for study following determination of personal and family disease history and karyological analysis. Skin fibroblasts from these individuals were tested for expression of SV40 T-antigen by indirect immunofluorescent assay. The data were normally distributed and showed no significant differences between the age, sex, or ethnic groups tested. The occurrence of rare karyological anomalies in this control population had no effect on T-antigen expression. Fibroblasts from 10 Fanconi anemia patients demonstrated significantly elevated expression of T antigen compared to the well-defined control population, based on simple statistical criteria. T-antigen expression was elevated in two young patients prior to the onset of anemia and did not appear to correlate with the incidence or severity of other specific symptoms. Thus, elevated T-antigen expression in Fanconi anemia fibroblasts reflects an actual defect at the cellular level, rather than clinical, age, sex or ethnic factors not previously considered.     

DNA polymerase ι compensates for Fanconi anemia pathway deficiency by countering DNA replication stress

Fanconi anemia (FA) is caused by defects in cellular responses to DNA crosslinking damage and replication stress. Given the constant occurrence of endogenous DNA damage and replication fork stress, it is unclear why complete deletion of FA genes does not have a major impact on cell proliferation and germ-line FA patients are able to progress through development well into their adulthood. To identify potential cellular mechanisms that compensate for the FA deficiency, we performed dropout screens in FA mutant cells with a whole genome guide RNA library. This uncovered a comprehensive genome-wide profile of FA pathway synthetic lethality, including POLI and CDK4. As little is known of the cellular function of DNA polymerase iota (Pol ι), we focused on its role in the loss-of-function FA knockout mutants. Loss of both FA pathway function and Pol ι leads to synthetic defects in cell proliferation and cell survival, and an increase in DNA damage accumulation. Furthermore, FA-deficient cells depend on the function of Pol ι to resume replication upon replication fork stalling. Our results reveal a critical role for Pol ι in DNA repair and replication fork restart and suggest Pol ι as a target for therapeutic intervention in malignancies carrying an FA gene mutation.

Fanconi anemia (FA) is a genomic instability disorder caused by biallelic or x-linked mutations in any of 22 genes. FA patients are characterized by multiple developmental abnormalities, progressive bone marrow failure, and profound cancer susceptibility (1–3). Germ-line FA mutations predispose an individual to breast, ovarian, pancreatic, and hematological malignancies. Somatic FA mutations have been identified in sporadic acute leukemia and breast cancer (4–6).The FA pathway is the major cellular mechanism responding to DNA crosslinking damage and replication stress. The 22 FA gene products fall into several functional groups. In response to DNA damage, the FANCD2/FANCI complex is monoubiquitinated, signifying the activation of the canonical FA pathway (7, 8). The monoubiquitinated FANCD2/FANCI complex most likely orchestrates the recruitment of nucleolytic factors for the processing of crosslinking DNA damage (9, 10). The FA core complex, consisting of FANCA, -B, -C, -E, -F, -G, and -M, FAAP20, FAAP24, FAAP100, and the RING domain protein FANCL, provides the E3 ligase activity for the damage-induced monoubiquitination of FANCD2/FANCI (11–16). FANCP/XPF and FANCQ/SLX4, the third group of FA gene products, are nucleases or part of the nuclease scaffold, taking part in DNA cleavage for the removal of the crosslinking lesions (8, 17–21). DNA double-strand breaks, as an intermediate structure of ICL (Interstrand CrossLink) repair, depend on the fourth group of FA proteins, required in homologous recombination (FANCD1/BRCA2, FANCO/RAD51C, FANCJ/BARD1, and FANCR/RAD51) (22–26).In addition to the direct role in crosslinking damage repair, FA pathway components are linked to the protection of replication fork integrity during replication interruption that is not directly caused by damage to the DNA. BRCA1/2 are important in stabilizing stalled forks in an MRE11-dependent manner (27, 28). Similarly, FANCD2 and FANCI have been shown to prevent collapse of stalled replication forks (29, 30). Defects in the FA and recombination mechanisms lead to severe fork erosion and endogenous DNA damage accumulation upon reversible replication block, suggesting that the FA pathway plays a crucial role in DNA replication under both normal and perturbed growth conditions (8, 23, 31–34).Given the important role of the FA pathway in replication stress, it is perplexing that cells with a completely impaired FA mechanism are capable of sustained proliferation (34, 35). Overt abnormalities are absent in mice with knockout of several key FA genes (36–39). Moreover, individuals can survive without a functional FA pathway for decades (median life expectancy of 30 y for FA patients) (40). More recently, a genome-scale CRISPR-Cas9 guide RNA (gRNA) library screen has defined gene sets essential for proliferation of common model cell lines (41). None of the classic FA genes which participate in the monoubiquitination process appear to be essential in these screens. Cells deficient in classic FA genes can sustain growth despite the accumulation of endogenous DNA damage. Thus, it seems likely that compensatory mechanisms exist in FA mutant cells to support long-term viability.In this study, we sought to identify cellular mechanisms that are important for the survival of cells deficient in the FA pathway. Comparative genome-scale CRISPR/Cas9 screens were carried out in isogenic FA pathway-proficient and -deficient cells. Genes that exhibit synthetic lethality in FA mutant cells are candidates which compensate for the loss of the FA pathway function. Among the top candidates, we validated and investigated DNA polymerase (Pol) ι as a critical factor for the survival of FA mutant cells. We found that, in FA-deficient cells, Pol ι is crucial in the resumption of stressed replication forks and in suppressing the accumulation of endogenous DNA damage. This reveals a function for Pol ι in relieving DNA damage stress.     

Three Cases of Esophageal Cancer Related to Fanconi Anemia

The risk of carcinogenesis increases after 20 years old in patients with Fanconi anemia (FA). We herein report three rare cases of FA combined with esophageal cancer in women; all patients were diagnosed with FA in early childhood. Patients 1 and 2 were diagnosed with advanced and superficial esophageal cancer, respectively, at 21 and 30 years old, respectively. Patient 3 was diagnosed with superficial esophageal cancer, underwent curative surgery at 26 years old, and survived for over 5 years without recurrence. Therefore, establishing a protocol for the early detection of esophageal cancer in FA patients over 20 years old is important.     

Treatment with Deferiprone for Iron Overload Alleviates Bone Marrow Failure in a Fanconi Anemia Patient

Fanconi anemia (FA) is a rare inherited disorder characterized by congenital abnormalities, progressive bone marrow failure and cancer susceptibility. There are no reports in the literature about a specific therapy effective in treating the progressive bone marrow failure of FA except for hematopoietic stem cell transplantation (HSCT). A FA patient started to receive deferiprone (L1) therapy due to iron overload. We report here that the white blood cell counts, hemoglobin (Hb) levels and platelet counts were significantly higher during the L1-treated period than when without L1 therapy. Therefore, L1 therapy may be worth considering for FA patients who cannot undergo HSCT.     

Molecular characterization of 11 novel mutations in patients with heterozygous and homozygous FV deficiency

Summary. Coagulation factor V (FV) has an important role in the blood coagulation cascade, in both the pro‐ and anticoagulant pathways. FV deficiency is a rare bleeding disorder with variable phenotypic expression. We report a cohort of 10 patients with mild‐severe FV deficiency in whom a total of 11 novel mutations were identified. Three patients were compound heterozygous for two mutations, whereas each of the remaining patients had a single heterozygous variant. FV levels did not correlate with either the type of mutation identified or the bleeding diathesis exhibited by the patients. Although considered to have an autosomal recessive mode of inheritance, patients with a single missense mutation may present with a significant bleeding history. The addition of a significant number of previously unidentified mutations to the public domain will contribute to the knowledge and understanding of the molecular pathology of this rare disorder.