Fanconi's anaemia and its variability

Eltrombopag Add-on Treatment in a Child With Fanconi Aplastic Anemia Awaiting Hematopoietic Stem Cell Transplantation

Fanconi aplastic anemia (FAA) is a rare inherited bone marrow failure disorder characterized by congenital defects and pancytopenia. Hematopoietic stem cell transplantation (HSCT) is a curative treatment for patients with FAA due to the risk of cancer and pancytopenia. Blood transfusions are the best supportive therapy. Oxymetholone (5 mg/kg daily) is most commonly used; however, it is not curative. Extensive transfusions should be avoided because of alloimmunization and graft-versus-host disease because they have poor outcomes in patients with HSCT. This is a case report of a 5-year-old Syrian male patient with FAA, who was successfully treated with eltrombopag (50 mg daily) in conjunction with oxymetholone (5 mg/kg daily). The patient required platelet transfusions despite oxymetholone therapy and there was no suitable donor for HSCT. After the addition of eltrombopag therapy, platelet transfusions were no longer required. Eltrombopag can be effectively used as a bridge to HSCT in patients with FAA.

Successful hematopoietic cell transplantation in Fanconi anemia patients with renal impairment using ultra-reduced doses of cyclophosphamide and fludarabine

Hematopoietic cell transplantation (HCT) remains until now the only curative modality for hematological manifestations in patients with Fanconi anemia (FA). The doses of alkylating agents used in the conditioning of this patient population before HCT are usually significantly decreased due to the genomic instability of the FA cells. FA patients with renal impairment represent a dilemma because of the need to further modify the conditioning regimen according to the degree of renal impairment to avoid additional toxicity. At our institution, we successfully transplanted three FA patients using an ultra-modified regimen.

Patterns and frequency of renal abnormalities in Fanconi anaemia: implications for long-term management

BACKGROUND

Fanconi anaemia (FA) is an inherited disease with bone marrow failure, variable congenital and developmental abnormalities, and cancer predisposition. With improved survival, non-haematological manifestations of FA become increasingly important for long-term management. While renal abnormalities are recognized, detailed data on patterns and frequency and implications for long-term management are sparse.

METHODS

We reviewed clinical course and imaging findings of FA patients with respect to renal complications in our centre over a 25-year period to formulate some practical suggestions for guidelines for management of renal problems associated with FA.

RESULTS

Thirty patients including four sibling sets were reviewed. On imaging, 14 had evidence of anatomical abnormalities of the kidneys. Two cases with severe phenotype, including renal abnormalities, had chronic kidney disease (CKD) at diagnosis. Haematopoietic stem cell transplantation was complicated by significant acute kidney injury (AKI) in three cases. In three patients, there was CKD at long-term follow-up. All patients had normal blood pressure.

CONCLUSIONS

Evaluation of renal anatomy with ultrasound imaging is important at diagnostic workup of FA. While CKD is uncommon at diagnosis, our data suggests that the incidence of CKD increases with age, in particular after haematopoietic stem cell transplantation. Monitoring of renal function is essential for management of FA. Based on these long-term clinical observations, we formulate some practical guidelines for assessment and management of renal abnormalities in FA.

Alpha-fetoprotein and Fanconi Anemia: Relevance to DNA Repair and Breast Cancer Susceptibility

Elevations of serum alpha-fetoprotein (sAFP) have been reported in fetal and infant states of anemia. Fanconi anemia (FA) belongs to a family of genetic instability disorders which lack the capability to repair DNA breaks. The lesion occurs at a checkpoint regulatory step of the G2 to mitotic transition, allowing FA cells to override cell-cycle arrest. FA DNA repair pathways contain complementation groups known as FANC proteins. FANC proteins form multi-protein complexes with BRCA proteins and are involved in homologous DNA repair. An impaired cascade in these events imparts an increased breast cancer susceptibility to female FA patients. Elevations of sAFP have availed this fetal protein to serve as a biomarker for FA disease. However, the origin of the synthesis of sAFA has not been determined in FA patients. We hypothesize that hematopoietic multipotent progenitor stem cells in the bone marrow are the source of sAFP production in FA patients.

Sequential renal and bone marrow transplants in a child with Fanconi anemia

FA is an autosomal recessive disorder characterized by small stature and renal abnormalities. FA can lead to progressive bone marrow failure, myelodysplastic syndrome, or acute leukemia. Using a multidisciplinary team approach, we managed a 3-yr-old boy with FA who simultaneously developed renal and hematopoietic failure. Because renal function was insufficient to support the conditioning regimen for HCT, we performed a deceased donor renal transplant in December 2012 prior to HCT with the known risk of graft-versus-graft rejection of the donor kidney. Seven months later he underwent allogeneic HCT. He obtained myeloid engraftment on day +11 and peripheral blood chimerism demonstrated all donor by day +21. He developed asymptomatic CMV reactivation and despite antirejection medications, mild skin graft-versus-host disease. He has maintained excellent renal function and remains transfusion independent with full hematopoietic recovery. He has not experienced any renal rejection episodes nor developed donor-specific antibodies toward his renal donor. Peripheral blood chimerism remains completely HCT donor. He is clinically well, now greater than two and a half yr after renal transplant and two yr after HCT. The continuing close collaboration between the Pediatric Nephrology and Bone Marrow Transplant teams is a major factor in this successful outcome.

Current insights into inherited bone marrow failure syndromes

Inherited bone marrow failure syndrome (IBMFS) encompasses a heterogeneous and complex group of genetic disorders characterized by physical malformations, insufficient blood cell production, and increased risk of malignancies. They often have substantial phenotype overlap, and therefore, genotyping is often a critical means of establishing a diagnosis. Current advances in the field of IBMFSs have identified multiple genes associated with IBMFSs and their pathways: genes involved in ribosome biogenesis, such as those associated with Diamond-Blackfan anemia and Shwachman-Diamond syndrome; genes involved in telomere maintenance, such as dyskeratosis congenita genes; genes encoding neutrophil elastase or neutrophil adhesion and mobility associated with severe congenital neutropenia; and genes involved in DNA recombination repair, such as those associated with Fanconi anemia. Early and adequate genetic diagnosis is required for proper management and follow-up in clinical practice. Recent advances using new molecular technologies, including next generation sequencing (NGS), have helped identify new candidate genes associated with the development of bone marrow failure. Targeted NGS using panels of large numbers of genes is rapidly gaining potential for use as a cost-effective diagnostic tool for the identification of mutations in newly diagnosed patients. In this review, we have described recent insights into IBMFS and how they are advancing our understanding of the disease's pathophysiology; we have also discussed the possible implications they will have in clinical practice for Korean patients.

FANCA and FANCG are the major Fanconi anemia genes in the Korean population

Fanconi anemia (FA) is a rare disorder characterized by physical abnormalities, bone marrow failure (BMF), increased risk of malignancies, and cellular hypersensitivity to DNA cross-linking agents. This study evaluated the genetic alterations in three major Fanconi genes (FANCA, FANCC, and FANCG) in 30 FA patients using multiplex ligation-dependent probe amplification and direct sequencing. Thirteen BMF patients were genetically classified as FA-A (n = 6, 46%) and FA-G (n = 7, 54%). Four common founder mutations were identified and included two FANCA mutations (c.2546delC and c.3720_3724delAAACA) and two FANCG mutations (c.307+1G>C and c.1066C>T), which had previously been commonly observed in a Japanese FA population. We also detected four novel deleterious mutations: c.2778+1G>C and c.3627-1G>A of FANCA, and c.1589_1591delATA and c.1761-1G>A of FANCG. This study shows that mutations in FANCA and FANCG are common in Korean FA patients and the existence of four common founder mutations in an East Asian FA population. Mutation screening workflow that includes these common mutations may be useful in the creation of an international database, and to better understand the ethnic characteristics of FA.

Preventing nonhomologous end joining suppresses DNA repair defects of Fanconi anemia

Fanconi anemia (FA) is a complex cancer susceptibility disorder associated with DNA repair defects and infertility, yet the precise function of the FA proteins in genome maintenance remains unclear. Here we report that C. elegans FANCD2 (fcd-2) is dispensable for normal meiotic recombination but is required in crossover defective mutants to prevent illegitimate repair of meiotic breaks by nonhomologous end joining (NHEJ). In mitotic cells, we show that DNA repair defects of C. elegans fcd-2 mutants and FA-deficient human cells are significantly suppressed by eliminating NHEJ. Moreover, NHEJ factors are inappropriately recruited to sites of replication stress in the absence of FANCD2. Our findings are consistent with the interpretation that FA results from the promiscuous action of NHEJ during DNA repair. We propose that a critical function of the FA pathway is to channel lesions into accurate, as opposed to error-prone, repair pathways.

Diagnosis of Fanconi anemia in patients with bone marrow failure

BACKGROUND

Patients with bone marrow failure and undiagnosed underlying Fanconi anemia may experience major toxicity if given standard-dose conditioning regimens for hematopoietic stem cell transplant. Due to clinical variability and/or potential emergence of genetic reversion with hematopoietic somatic mosaicism, a straightforward Fanconi anemia diagnosis can be difficult to make, and diagnostic strategies combining different assays in addition to classical breakage tests in blood may be needed.

DESIGN AND METHODS

We evaluated Fanconi anemia diagnosis on blood lymphocytes and skin fibroblasts from a cohort of 87 bone marrow failure patients (55 children and 32 adults) with no obvious full clinical picture of Fanconi anemia, by performing a combination of chromosomal breakage tests, FANCD2-monoubiquitination assays, a new flow cytometry-based mitomycin C sensitivity test in fibroblasts, and, when Fanconi anemia was diagnosed, complementation group and mutation analyses. The mitomycin C sensitivity test in fibroblasts was validated on control Fanconi anemia and non-Fanconi anemia samples, including other chromosomal instability disorders.

RESULTS

When this diagnosis strategy was applied to the cohort of bone marrow failure patients, 7 Fanconi anemia patients were found (3 children and 4 adults). Classical chromosomal breakage tests in blood detected 4, but analyses on fibroblasts were necessary to diagnose 3 more patients with hematopoietic somatic mosaicism. Importantly, Fanconi anemia was excluded in all the other patients who were fully evaluated.

CONCLUSIONS

In this large cohort of patients with bone marrow failure our results confirmed that when any clinical/biological suspicion of Fanconi anemia remains after chromosome breakage tests in blood, based on physical examination, history or inconclusive results, then further evaluation including fibroblast analysis should be made. For that purpose, the flow-based mitomycin C sensitivity test here described proved to be a reliable alternative method to evaluate Fanconi anemia phenotype in fibroblasts. This global strategy allowed early and accurate confirmation or rejection of Fanconi anemia diagnosis with immediate clinical impact for those who underwent hematopoietic stem cell transplant.

Acquired chromosome instability in the elderly--the effect of diepoxybutane

Aging and Alzheimer's disease (AD) have been the subject of many studies. It has been suggested that chromosomal alterations may be involved in the etiology and/or pathogenesis of ageing and AD. The purpose of the present study was to examine the effect of diepoxybutane (DEB) on lymphocyte chromosomal instability in the elderly. We examined lymphocytes cytogenetically with, as well as, without DEB treatment, in a group of 12 elderly (range of age 72-96 years), nine of them suffering from AD type. Without DEB treatment six of the donors expressed chromosomal instability in at least 6% of the analyzed cells. After treatment with DEB, lymphocytes showed an increase in the chromosomal instability in up to 20% of the analyzed in eight donors. The sex chromosomes were the main chromosomes involved in the acquired chromosomal abnormalities. It is not clear from this study whether this chromosomal instability is related to the AD. The significance of the involvement of sex chromosomes either in ageing or in AD, as well as, the question whether the chromosomal instability is the cause of or part of ageing processes, has to be addressed.

What's in a cancer syndrome? Genes, phenotype and pathology

Syndromes are characterised by a group of specific signs and symptoms. This review aims to provide an overview of cancer syndromes and sheds light on possible roles for general health professionals in relation to their abilities to identify patients with cancer syndromes and therefore to refer such patients to specialists.

L'anémie de Fanconi : aspects cellulaires et moléculaires

Fanconi anemia (FA) is a recessive human cancer prone syndrome featuring bone marrow failure, developmental abnormalities and hypersensitivity to DNA crosslinking agents exposure. 11 among 12 FA gene have been isolated. The biochemical functions of the FANC proteins remain poorly understood. Anyhow, to cope with DNA crosslinks a cell needs a functional FANC pathway. Moreover, the FANC proteins appear to be involved in cell protection against oxidative damage and in the control of TNF-alpha activity. In this review, we describe the current understanding of the FANC pathway and we present how it may be integrated in the complex networks of proteins involved in maintaining the cellular homeostasis.

Hereditary and familial syndromes of bone and blood. Genetic pathways, diagnostic pitfalls

Numerous metabolic disorders, teratogenic agents, and in utero infections lead to congenital bone disease and malformation. This review focuses on hereditary and familial disorders of bone with particular emphasis on impaired hematopoiesis, myelofibrosis, pathologic fractures, and dysmorphology of the forearm and craniofacial structures. The severity of bone disease and marrow dysfunction of any given disorder may vary considerably from one affected individual to the next, and intrapersonal variability over time may be substantial as well. Both can impart difficulty to the appropriate evaluation and delay the correct diagnosis. Many of these disorders are phenotypically quite similar but require very different therapeutic intervention.

Bone marrow transplantation from matched related donors for patients with Fanconi anemia using low-dose busulfan and cyclophosphamide as conditioning

Seventeen patients with Fanconi anemia (FA) underwent allogeneic bone marrow transplantation (BMT) from matched related donors (MRD) between January 1999 and June 2003. Median age at BMT was 11 years. Conditioning regimen consisted of low-dose cyclophosphamide (CY; 40 mg/kg) and busulfan (BU; 6 mg/kg) with the addition of lymphoglobulin (20 mg/kg) in two patients. Graft-versus-host disease (GVHD) prophylaxis included cyclosporine A (CsA) and methotrexate (MTX; 5 mg/m(2) at day 1, 3, 6). All patients engrafted (for an absolute neutrophil count >0.5 x 10(9)/L) after a median time of 12 days (range 10-16 days). Fourteen patients (82%) had sustained grafts, whereas three others (18%) rejected grafts between day +39 and +80 after transplantation. Two of them are still alive after successful second PBSC transplantation and one died. Acute and chronic GVHD occurred in 23% and 13% of patients, respectively. With a median follow-up of 16 months (range 3-53 months), survival rate was 72% and Karnofsky score was at least 90%. The low-dose BU/CY regimen, in FA patients allografted from an HLA-matched related donor, allowed engraftment with relative low toxicity. Early graft failure (GF) remains a problem and may require modification of this regimen.

The rule of four: a systematic approach to diagnosis of common pediatric hematologic and oncologic disorders

The "Rule of Four" facilitates a rapid and focused approach to the diagnosis of the common hematologic and oncologic disorders encountered in general pediatric practice. This system relies on four recurrent but different clinical entities or laboratory tests relevant to the diagnosis of children with anemia, excessive bleeding or clotting, and common malignancies. For each disorder, there is a discussion of a variety of four lab tests or factors pertinent to a differential diagnosis.

3R coordination by Fanconi anemia proteins

Fanconi anemia (FA) is a recessive cancer prone syndrome featuring bone marrow failure and hypersensitivity to DNA crosslinks. Nine FA genes have been isolated so far. The biochemical function(s) of the FA proteins remain(s) poorly determined. However, a large consensus exists on the evidence that, to cope with DNA cross-links, a cell needs a functional FA pathway. In this review, we resume current understanding of how the FA pathway works in response to DNA damage and how it is integrated in a complex network of proteins involved in the maintenance of the genetic stability.

Oxidative stress as a multiple effector in Fanconi anaemia clinical phenotype

Fanconi anaemia (FA) is a genetic disease characterised by bone marrow failure with excess risk of myelogenous leukaemia and solid tumours. A widely accepted notion in FA research invokes a deficiency of response to DNA damage as the fundamental basis of the 'crosslinker sensitivity' observed in this disorder. However, such an isolated defect cannot readily account for the full cellular and clinical phenotype, which includes a number of other abnormalities, such as malformations, endocrinopathies, and typical skin spots. An extensive body of evidence pointing toward an involvement of oxidative stress in the FA phenotype includes the following: (i) In vitro and ex vivo abnormalities in a number of redox status endpoints; (ii) the functions of several FA proteins in protecting cells from oxidative stress; (iii) redox-related toxicity mechanisms of the xenobiotics evoking excess toxicity in FA cells. The clinical features in FA and the in vivo abnormalities of redox parameters are here reconsidered in view of the pleiotropic clinical phenotype and known biochemical and molecular links to an in vivo prooxidant state, which causes oxidative damage to biomolecules, resulting in an excessive number of acquired abnormalities that may overwhelm the cellular repair capacity rather than a primary deficiency in DNA repair. FA may thus represent a unique model disease in testing the integration between the acquisition of macromolecular damage as a result of oxidative stress and the ability of the mammalian cell to respond effectively to such damage.

Stem cell transplantation for patients with Fanconi anemia with low-dose cyclophosphamide and antithymocyte globulins without the use of radiation therapy

In all, 22 patients with confirmed Fanconi anemia (FA) underwent stem cell transplantation (SCT) from HLA-matched, related donors at KFSHRC. Median age at SCT was 7.6 years (range, 2.5-14.6 years). Conditioning regimen consisted of cyclophosphamide (CY) 15 mg/kg/day intravenously (i.v.) for 4 consecutive days, in addition to equine antithymocyte globulins (ATG) given i.v. at 40 mg/kg/day for four doses pre-SCT. No radiation therapy was given. For graft-versus-host disease prophylaxis, we used cyclosporin at the standard doses; ATG was added at 20 mg/kg/dose i.v. on days 2, 4, 6, 8, 10, and 12 post-SCT (total of six doses). All patients engrafted and are alive and transfusion independent with a median follow-up time of 20.2 months (range, 3.3-59 months). One patient however developed a decrease in her WBC and platelet count. Her work-up revealed slightly hypocellular bone marrow, and a series of chimerism studies over 1 year confirmed that she has stable mixed chimerism; she remains transfusion independent. We conclude that low-dose CY without radiation therapy can be used satisfactorily in the conditioning of patients with FA undergoing related SCT.

Fanconi anemia: contribution of molecular analyses to the identification of bone marrow graft donors and the study of chimerism in grafted patients

We report on the effectiveness of molecular studies regarding Fanconi anemia (FA) for a better selection of bone marrow graft donors and for post-transplant follow up. Ten unrelated FA patients and their families were analyzed by microsatellite markers. In 9 cases, the cytogenetic investigation of potential human leukocyte antigen (HLA)-identical related donors was normal, and the molecular analyses confirmed that they were also either normal or heterozygous carriers. For 1 patient, cytogenetic analysis of an HLA-identical sibling donor yielded ambiguous results with a relatively high number of chromosomal breakages using cross-linking agents. However, genotyping of this potential donor demonstrated his heterozygous state. Nine patients have received allogeneic bone marrow transplantation from HLA-matched related donors. Microsatellite analysis showed complete chimerism (CC) in all cases. The median follow up was 54 months (range 8-144 months). One patient out of 9 with CC rejected her graft without prior detection of a transitional mixed chimerism. Among these patients, 1 died 25 months after the transplantation of a chronic graft-versus-host-disease (GVHD). We conclude that, when the cytogenetic studies are not conclusive, molecular analyses are crucial to distinguish heterozygous carriers from asymptomatic FA Tunisian patients. Molecular analyses also allowed the evaluation of hematopoietic chimerism after allogeneic bone marrow transplantation and might be of value to identify patients with a high risk for graft rejection.

Stem cell clonality and genotoxicity in hematopoietic cells: Gene activation side effects should be avoidable

Two serious adverse events involving activation of the LMO2 oncogene through retrovirus vector insertion in the otherwise extremely successful first gene therapy trial for X-linked severe combined immunodeficieny type 1 (SCID-X1) had initially caused widespread concern in the patient and research communities. Careful consideration 1 year after diagnosis of the second case still finds 12 of the treated patients clearly benefiting from gene therapy (freedom from treatment failure, 80%; survival 100%), a situation that should not portend the end of gene therapy for this disease, and is, in fact encouraging. While current approaches are justified to treat patients with otherwise life-threatening disorders, a broad consensus has developed that systematic basic research is required to further understand the pathophysiology of these serious adverse events and to provide new insights, enabling safer and more effective gene therapy strategies. With the continued success of SCID-X1 gene therapy in the majority of patients treated, it is of even greater importance to understand exactly which vector element or combination of elements predispose to toxicity. An in-depth study of the mechanisms behind the activation of the LMO2 and gammac genes will be highly instructive for the development of safer procedures and vectors. We summarize the central observations, ongoing experimental approaches, new concepts, and developments relevant to understanding, interpreting, and eventually overcoming the real and perceived obstacles posed by insertional mutagenesis due to gene transfer vectors.

Recurrent aphthous ulcers in Fanconi's anaemia: a case report

Fanconi's anaemia (FA) is an autosomal recessive disorder that is clinically characterized by aplastic anaemia, congenital malformations of the renal, cardiac, skeletal and skin structures, and an increased predisposition to malignancies. Patients with FA often present with bleeding and infection, which are symptoms related to thrombocytopenia and neutropenia. There are few reports of the oral manifestations of FA. We describe oral aphthous ulcerations in two siblings with FA. There was a rapid improvement and healing of ulcers after blood transfusions and increased haemoglobin levels. This may support the role of severe anaemia in oral ulcerations.

Klippel-Feil anomaly in Fanconi anemia

A boy is described with Fanconi anemia (FA) and Klippel-Feil anomaly. This suggests the diagnosis of FA should be considered in patients with vertebal malformations as well as other suggestive congenital anomalies.

Epithelial cancer in Fanconi anemia complementation group D2 (Fancd2) knockout mice

Fanconi anemia (FA) is a genetic disorder characterized by hypersensitivity to DNA damage, bone marrow failure, congenital defects, and cancer. To further investigate the in vivo function of the FA pathway, mice with a targeted deletion in the distally acting FA gene Fancd2 were created. Similar to human FA patients and other FA mouse models, Fancd2 mutant mice exhibited cellular sensitivity to DNA interstrand cross-links and germ cell loss. In addition, chromosome mispairing was seen in male meiosis. However, Fancd2 mutant mice also displayed phenotypes not observed in other mice with disruptions of proximal FA genes. These include microphthalmia, perinatal lethality, and epithelial cancers, similar to mice with Brca2/Fancd1 hypomorphic mutations. These additional phenotypes were not caused by defects in the ATM-mediated S-phase checkpoint, which was intact in primary Fancd2 mutant fibroblasts. The phenotypic overlap between Fancd2-null and Brca2/Fancd1 hypomorphic mice is consistent with a common function for both proteins in the same pathway, regulating genomic stability.

DEB test for Fanconi anemia detection in patients with atypical phenotypes

Pancytopenia, hyperpigmentation, small stature, congenital abnormalities, and predisposition to neoplasia characterize Fanconi anemia (FA). The clinical phenotype is extremely variable, therefore the diagnosis is frequently delayed until the pancytopenia appears, making diagnosis difficult on the basis of clinical manifestations alone. Hypersensitivity of FA cells to the clastogenic effect of diepoxybutane (DEB) provides a unique marker for the diagnosis before the beginning of hematological manifestations. Our aim in this study was to detect FA in children with atypical manifestations to define which conditions should be routinely included in the DEB test screening. We performed the chromosomal breakage test in 34 patients with probable FA and 83 patients with clinical conditions that could suggest FA, but are not usually screened by the DEB test: 20 patients with aplastic anemia, 20 patients with VACTERL association, 20 with radial ray abnormalities, 7 with tracheo-esophageal fistulae, 12 with anal atresia, and 4 with myelodysplastic syndrome. We found 18 DEB-positive patients: 12 were in the group of probable FA and 6 in the other groups. Among the last ones: three were included because of aplastic anemia, without any other sign of FA, however when re-examined, other anomalies were detected. The third patient had anal atresia, renal hypoplasia, pre-axial polydactyly, and normal blood cell counts and was diagnosed as having VACTERL association. The other two patients lacking physical or hematological signs were identified among the group of radial ray abnormalities. Thus, our results highlight the need to increase the number of abnormalities indicating need for a DEB test. Delay in the diagnosis of FA may have serious consequences for the patients and their family members.

Serum alpha-fetoprotein level in Fanconi's anemia: evaluation of 33 Turkish patients

Recently, measurement of serum alpha-fetoprotein (sAFP) was introduced as a preliminary test for diagnosis of Fanconi's anemia (FA). In the present study, sAFP levels were measured in order to determine its sensitivity and specificity in 33 Turkish FA patients (17 males and 16 females) with a mean age of 11.6 +/- 7.7 (1.0-28.0) (median 10.0). Complementation groups were available in 12 patients. Nineteen age-matched healthy children, 17 patients with bone marrow failure syndromes, 37 FA heterozygotes, and 37 children with acute leukemia served as negative control groups. The sAFP was measured by particle immunoassay. The level of sAFP was found to be higher than the cut-off value, 8 IU/mL in 46% and was within normal limits in 54% of the FA patients. The AFP values were within normal limits in all of the subjects belonging to the control groups. This method provided 46% sensitivity and 100% specificity in the diagnosis of FA. The sAFP values were high in 4 of 17 (24%) FA patients who did not receive any androgen therapy, while the sAFP level was high in 7 of 9 (78%) patients who received such a therapy. The statistical analysis of incidence of a high sAFP level between these two groups indicated a significant difference (P = 0.014), suggesting that androgen therapy might be a contributing factor for elevation of sAFP. The comparison of several clinical and laboratory parameters between FA patients with high and normal levels of AFP revealed no statistically significant differences. The level of sAFP was elevated in only 5 of the 11 patients with complementation group A; in addition, variable levels of sAFP were noted among the affected members in 4 families, indicating that complementation groups, type of mutation, or familial factors were not responsible for elevation of sAFP.

Gene therapy of Fanconi anemia: preclinical efficacy using lentiviral vectors

Fanconi anemia (FA) is an inherited cancer susceptibility syndrome caused by mutations in a DNA repair pathway including at least 6 genes (FANCA, FANCC, FANCD2, FANCE, FANCF, and FANCG). The clinical course of the disease is dominated by progressive, life-threatening bone marrow failure and high incidence of acute myelogenous leukemia and solid tumors. Allogeneic bone marrow transplantation (BMT) is a therapeutic option but requires HLA-matched donors. Gene therapy holds great promise for FA, but previous attempts to use retroviral vectors in humans have proven ineffective given the impaired proliferation potential of human FA hematopoietic progenitors (HPCs). In this work, we show that using lentiviral vectors efficient genetic correction can be achieved in quiescent hematopoietic progenitors from Fanca(-/-) and Fancc(-/-) mice. Long-term repopulating HPCs were transduced by a single exposure of unfractionated bone marrow mononuclear cells to lentivectors carrying the normal gene. Notably, no cell purification or cytokine prestimulation was necessary. Resistance to DNA- damaging agents was fully restored by lentiviral transduction, allowing for in vivo selection of the corrected cells with nonablative doses of cyclophosphamide. This study strongly supports the use of lentiviral vectors for FA gene therapy in humans.

Fanconi anemia group A and C double-mutant mice: functional evidence for a multi-protein Fanconi anemia complex

OBJECTIVE

Fanconi anemia (FA) is a genetically heterogeneous disorder associated with defects in at least eight genes. The biochemical function(s) of the FA proteins are unknown, but together they define the FA pathway, which is involved in cellular responses to DNA damage and in other cellular processes. It is currently unknown whether all FA proteins are involved in controlling a single function or whether some of the FA proteins have additional roles. The aim of this study was 1) to determine whether the FA group A and group C genes have identical or partially distinct functions, and 2) to have a better model for human FA.

MATERIALS AND METHODS

We generated mice with a targeted mutation in fanca and crossed them with fancc disrupted animals. Several phenotypes including sensitivity to DNA cross linkers and ionizing radiation, hematopoietic colony growth, and germ cell loss were analyzed in fanca-/-, fancc-/-, fanca/fancc double -/-, and controls.

RESULTS

Fibroblast cells and hematopoietic precursors from fanca/fancc double-mutant mice were not more sensitive to MMC than those of either single mutant. fanca/fancc double mutants had no evidence for an additive phenotype at the cellular or organismal level.

CONCLUSIONS

These results support a model where both FANCA and FANCC are part of a multi-protein nuclear FA complex with identical function in cellular responses to DNA damage and germ cell survival.

Overexpressed thioredoxin compensates Fanconi anemia related chromosomal instability

The cause of the molecular defect of Fanconi anemia (FA) remains unknown. Cells from patients with FA exert an elevated spontaneous chromosomal instability which is further triggered by mitomycin C. The induced lability is reduced by overexpression of thioredoxin which is not the case for spontaneous instability. However, both are eliminated by overexpression of thioredoxin cDNA with an added nuclear localization signal. This implies that thioredoxin is lacking in the nuclei of FA cells. The total thioredoxin content in all FA cells tested is reduced. The resultant lack of nuclear thioredoxin can be the explanation for the major symptomatology in FA. Since thioredoxin is known to be the reactive cofactor of ribonucleotid reductase its shortcoming reduces the supply of deoxyribonucleotides thus hindering the DNA and replication repair with resultant chromosomal breaks. Furthermore, depression of tyrosine hydroxylase, the key enzyme of melanine synthesis, could be the basis for the pathognomotic 'café au lait' spots of FA. The observation of thioredoxin reduction in FA cells permits insight into the molecular phathophysiology of FA.

Absence of thumbs, A/hypoplasia of radius, hypoplasia of ulnae, retarded bone age, short stature, microcephaly, hypoplastic genitalia, and mental retardation

The previously unreported combination of bilateral absence of thumbs, aplasia of ulna at one and hypoplasia of ulna on the other side, retarded bone age, short stature, microcephaly, micropenis, cryptorchidism, and mental retardation is described in a 5-year-old boy. Having excluded major differential diagnoses, e.g. Fanconi anemia, RAPADILINO syndrome and VACTERL association, we hypothesize that this boy represents a new multiple congenital anomaly/mental retardation (MCA/MR) syndrome.

Marrow failure

This chapter describes the clinical presentation and molecular basis of two inherited bone marrow failure syndromes, Fanconi anemia (FA), and Diamond-Blackfan anemia (DBA). It also provides an update on diagnostic and therapeutic approaches to bone marrow failure of all types (inherited and acquired) in pediatric patients. In Section I, Dr. Alan D'Andrea reviews the wide range of clinical manifestations of Fanconi anemia. Significant advances have been made in understanding the molecular pathogenesis of FA. On the basis of these advances, new diagnostic assays and treatment options are now available. In Section II, Dr. Niklas Dahl examines the clinical features and molecular pathogenesis of Diamond-Blackfan anemia. The possible links between the RPS19 gene (DBA gene) and the erythropoiesis defect are considered. In Section III, Drs. Eva Guinan and Akiko Shimamura provide an algorithm for the diagnostic evaluation and treatment of children with inherited or acquired aplastic anemia. Through the presentation of a case study of a pediatric patient with bone marrow failure, he provides an overview of the newest tests and treatment options.

The Chinese hamster FANCG/XRCC9 mutant NM3 fails to express the monoubiquitinated form of the FANCD2 protein, is hypersensitive to a range of DNA damaging agents and exhibits a normal level of spontaneous sister chromatid exchange

Fanconi anemia (FA) is a human autosomal disorder characterized by cancer susceptibility and cellular sensitivity to DNA crosslinking agents such as mitomycin C and diepoxybutane. Six FA genes have been cloned including a gene designated XRCC9 (for X-ray Repair Cross Complementing), isolated using a mitomycin C-hypersensitive Chinese hamster cell mutant termed UV40, and subsequently found to be identical to FANCG. A nuclear complex containing the FANCA, FANCC, FANCE, FANCF and FANCG proteins is needed for the activation of a sixth FA protein FANCD2. When monoubiquitinated, the FANCD2 protein co-localizes with the breast cancer susceptibility protein BRCA1 in DNA damage induced foci. In this study, we have assigned NM3, a nitrogen mustard-hypersensitive Chinese hamster mutant to the same genetic complementation group as UV40. NM3, like human FA cell lines (but unlike UV40) exhibits a normal spontaneous level of sister chromatid exchange. We show that both NM3 and UV40 are also hypersensitive to other DNA crosslinking agents (including diepoxybutane and chlorambucil) and to non-crosslinking DNA damaging agents (including bleomycin, streptonigrin and EMS), and that all these sensitivities are all corrected upon transfection of the human FANCG/XRCC9 cDNA. Using immunoblotting, NM3 and UV40 were found not to express the active monoubiquitinated isoform of the FANCD2 protein, although expression of the FANCD-L isoform was restored in the FANCG cDNA transformants, correlating with the correction of mutagen-sensitivity. These data indicate that cellular resistance to these DNA damaging agents requires FANCG and that the FA gene pathway, via its activation of FANCD2 and that protein's subsequent interaction with BRCA1, is involved in maintaining genomic stability in response not only to DNA interstrand crosslinks but also a range of other DNA damages including DNA strand breaks. NM3 and other "FA-like" Chinese hamster mutants should provide an important resource for the study of these processes in mammalian cells.

Aggressive periodontitis associated with Fanconi's anemia. A case report

BACKGROUND

Fanconi's anemia is an autosomal recessive disease associated with chromosomal breakage as well as pancytopenia, skin pigmentation, renal hypoplasia, cardiac defects, microcephaly, congenital malformations of the skeleton, hypogonadism, and increased risk of leukemia. The present report describes the periodontal clinical and microbiological status of an 11-year old male having Fanconi's anemia.

METHODS

Polymerase chain reaction analysis to detect human cytomegalovirus (HCMV), Epstein-Barr type 1 virus, and herpes simplex virus (HSV) was performed on paper-point samples pooled from either 3 periodontal sites with advanced attachment loss or 3 gingivitis sites with no clinical attachment loss. Anaerobic bacterial culture examination was performed on the pooled periodontitis sample.

RESULTS

The patient suffered from pancytopenia, allergy, asthma, hearing impairment, and mental retardation. Dentition consisted of 7 primary teeth, 11 erupted permanent teeth, and 14 unerupted permanent teeth. Most erupted teeth showed severe gingival inflammation with some gingival overgrowth and various degrees of periodontal attachment loss. Genomes of HCMV and HSV were detected in the pooled periodontitis sample and HCMV in the pooled gingivitis sample. The periodontitis sample but not the gingivitis sample revealed HCMV mRNA of major capsid protein, suggestive of active viral infection. The periodontitis sample also yielded Actinobacillus actinomycetemcomitans (1.1% of total isolates), FusobActerium species (7.9%), Campylobacter species (2.2%), Peptostreptococcus micros (3.4%), and Candida albicans (0.3%).

CONCLUSIONS

Oral features of Fanconi's anemia may include increased susceptibility to periodontitis. It is likely that underlying host defense impairment coupled with periodontal infection by HCMV and A. actinomycetemcomitans contribute to the severe type of periodontitis associated with Fanconi's anemia.

Thrombocytopenia absent corpus callosum syndrome: third case of a distinct clinical entity

Thrombocytopenia absent corpus callosum, characterized by refractory thrombocytopenia, agenesis of the corpus callosum, hypoplastic cerebellum, abnormal facies, and developmental delay, represents a relatively newly described clinical entity. An 18-month-old girl with agenesis of the corpus callosum, hypoplasia of the cerebellar vermis, hypotonia, and severe developmental delay presented with thrombocytopenia. She had a distinctive facies with microcephaly, broad nasal root with upturned nose, small upper lip, and micrognathia. A bone marrow aspirate and biopsy showed normal cellularity with dysplastic megakaryocytes. Thrombocytopenia absent corpus callosum is compared with other conditions characterized by congenital non-immune thrombocytopenia.

[Bone marrow transplantation in Fanconi's anemia: report of seven cases]

OBJECTS

Follow-up of patients with Fanconi's anemia treated in our unit and review of the literature concerning bone marrow transplantation in Fanconi's anemia.

PATIENTS AND METHODS

Ten patients were followed in our unit for 20 years. We summarize their clinical features, treatment and clinical course.

RESULTS

Among the ten patients, seven received allogeneic marrow transplantation. Only two patients are still alive. Two transplanted patients died from complications shortly after the transplantation. Three other patients died later after the transplantation, two of them from oropharyngeal carcinomas.

DISCUSSION

The 5-year survival is about 70% in the transplantation with an HLA-identical sibling donor; it is only about 30% if the donor is an HLA-matched unrelated or mismatched related patient. Furthermore, retrospective studies have shown that the long-term outcome of carcinoma is a major complication after the transplantation.

CONCLUSION

Our series of patients with Fanconi's anemia reflects fairly faithfully the complications encountered in this disease. Although the improvement of the graft technique may decrease the rate of death due to transplantation, the long-term development of solid tumors remains a problem for which no solution has been suggested up to now.

[Fanconi's anemia and molecular biology research]

Fanconi's anemia is a rare autosomal recessive disease characterized by congenital abnormalities, a progressive pancytopenia and a predisposition to cancer. The diagnosis is based on an abnormal increase of spontaneous chromosome breakage, more specifically on a clear-cut increase of chromosome breakage in the presence of bifunctional alkylating agents. Eight complementation groups (A to H) have been defined, and the genes corresponding to four of these groups have been cloned (FANCA, FANCC, FANCF and FANCG). The function of the proteins encoded by the genes of Fanconi's anemia remains unknown. Numerous studies indicate that different cellular processes are probably involved, including DNA repair pathways, apoptosis, cell cycle regulation and oxygen metabolism. Nevertheless, the exact cellular and molecular mechanisms implicated in Fanconi's anemia remain a challenge for fundamental research. The treatment of Fanconi's anemia is also the subject of intense research, bearing principally upon bone marrow transplantation, which is successful in the case of HLA-identical sibling donors, and gene therapy, which is still at a preliminary stage on the clinical level.

Normal cellular radiosensitivity in an adult Fanconi anaemia patient with marked clinical radiosensitivity

BACKGROUND

Fanconi anaemia is a rare disease associated with cellular sensitivity to chemicals (e.g. mitomycin C and diepoxybutane); variable but mild cellular radiosensitivity has also been reported.

MATERIALS AND METHODS

A 32-year-old patient with Fanconi anaemia and tonsillar carcinoma, treated by radiotherapy, was found to exhibit profound clinical radiosensitivity. Confluent, ulcerating oropharyngeal mucositis developed after a conventionally fractionated dose of 34Gy and healing was incomplete by 2 months after cessation of therapy.

RESULTS

Cellular radiosensitivity assays and RPLD studies from this patient did not suggest any major detectable radiosensitivity.

CONCLUSION

There is a discrepancy between the observed clinical radiosensitivity and the usual "predictive" radiosensitivity assays in this patient with Fanconi anaemia.

Current knowledge on the pathophysiology of Fanconi anemia: from genes to phenotypes

Fanconi anemia (FA) is an autosomal recessive disease characterized by congenital anomalies, bone marrow failure, and leukemia susceptibility. FA cells show chromosome instability and hypersensitivity to DNA cross-linking agents such as mitomycin C. Recent studies indicate that there are at least 8 genetically distinct FA groups (A, B, C, D1, D2, E, F, G). To date, 6 genes (for A, C, D2, E, F, and G) have been cloned. In this review, we describe the structures and functions of FA proteins. Increasing evidence indicates that the multiple FA proteins cooperate in a biochemical pathway and/or a multimer complex. FANCD2, a downstream component of the FA pathway, has recently been shown to be ubiquitinated in response to DNA damage and to translocate to nuclear foci containing BRCA1, a breast cancer susceptibility gene product, suggesting a role for this protein in DNA repair functions. We also describe 2 emerging issues: genotype-phenotype relationships and mosaicism. The FA pathway is likely to play a critical role as a caretaker of genomic integrity in hematopoietic stem cells. Clarifying the molecular basis of this disease may provide new insights into the pathogenesis of bone marrow failure syndromes and myeloid malignancies.

Episphalosomic syndrome : a MCA syndrome ressembling Fanconi anemia, with increased baseline level of chromosome breaks but no hypersensivity to clastogens

We describe a child with facial dysmorphism (trigonocephaly, epicanthus, upturned nose, small ears), thumb hypoplasia, micropenis, jejunal atresia and moderate mental retardation with dysphasia. Cytogenetic workup revealed high spontaneous level of chromosomal aberrations (without specific pattern and no quadriradial figures) and borderline to absent hypersensitivity to mitomycin C, making a diagnosis of Fanconi anemia unlikely. The child described here shares similarities with a small number of previous reports. We suggest to refer to this entity as episphalosomic syndrome. Episphalosomic syndrome shows some clinical overlap with Fanconi anemia, but lacks its cytogenetic hallmark. The hematological complications of Fanconi anemia have not been reported in this entity.

Positional cloning of a novel Fanconi anemia gene, FANCD2

Fanconi anemia (FA) is a genetic disease with birth defects, bone marrow failure, and cancer susceptibility. To date, genes for five of the seven known complementation groups have been cloned. Complementation group D is heterogeneous, consisting of two distinct genes, FANCD1 and FANCD2. Here we report the positional cloning of FANCD2. The gene consists of 44 exons, encodes a novel 1451 amino acid nuclear protein, and has two protein isoforms. Similar to other FA proteins, the FANCD2 protein has no known functional domains, but unlike other known FA genes, FANCD2 is highly conserved in A. thaliana, C. elegans, and Drosophila. Retroviral transduction of the cloned FANCD2 cDNA into FA-D2 cells resulted in functional complementation of MMC sensitivity.

Growth hormone deficiency caused by pituitary stalk interruption in Fanconi's anemia

Fanconi's anemia can be associated with growth retardation. We describe biologic growth hormone deficiency, isolated or associated with thyrotropin abnormality, and pituitary stalk interruption syndrome on magnetic resonance imaging of 5 patients with Fanconi's anemia. Growth hormone treatment produced catch-up growth in all cases. These findings suggest a common genetic origin.

Bone marrow transplantation from matched siblings in patients with fanconi anemia utilizing low-dose cyclophosphamide, thoracoabdominal radiation and antithymocyte globulin

Nineteen patients with Fanconi anemia (FA) and bone marrow failure underwent bone marrow transplantation (BMT) from matched siblings. Median age at BMT was 8.7 years. Conditioning consisted of low-dose cyclophosphamide (CY 5 mg/kg x 4 days) and thoracoabdominal irradiation (TAI 400 cGy). Graft-versus-host disease (GVHD) prophylaxis was cyclosporin A (CsA) in 13 patients and CsA plus methotrexate in 6 patients. Antithymocyte globulin (ATG) was added in the pretransplant as well as the post-transplant period. All patients received high-dose acyclovir from day 2 pre-BMT to day 28 post BMT, and intravenous immunoglobulins (IVIG), 500 mg/kg weekly from day 7 pre-BMT to day 90 post BMT. No fungal prophylaxis was given. All patients engrafted, (median, 14 days for an absolute neutrophil count > or =0.5 x 10(9)/l; median, 37 days for platelet count > or =20 x 10(9)/l). Fourteen (74%) patients are alive with sustained engraftment and are transfusion independent. Three (16.6%) patients developed acute GVHD; none developed chronic GVHD. Five (26%) patients developed invasive fungal infections, and two (10%) developed fatal CMV disease. We believe the addition of ATG may have contributed to the increased incidence of severe life-threatening fungal and viral infections in our series.

Successful haploidentical bone marrow transplantation in Fanconi anemia

A 10-year-old girl with Fanconi anemia and severe aplastic anemia underwent a haploidentical BMT from her mother due to lack of a matched family donor. T cell depletion was done by positive selection of CD34 cells with immunomagnetic beads. Due to graft rejection a second haploidentical BMT from the father was successfully undertaken. No immunosuppression was given after the transplant. Immunological reconstitution took approximately 6 months, with no GVHD or severe infections. Such a transplant, containing a large purified CD34 cell fraction with a minimal number of added T cells, should be considered as the treatment of choice for patients with Fanconi anemia if no HLA matched donor is available.

Growth hormone deficiency in one of two siblings with Fanconi's anaemia complementation group FA-D

Fanconi's anaemia (FA) shows great variability in phenotypic symptoms. We report on two FA siblings of German ancestry with the very rare form of the complementation group FA-D. Both presented with a similar phenotype and mild disease severity but with different growth. In the sister, growth velocity was normal, puberty and menarche occurred spontaneously. Her final height was within her parental target height. The younger brother had a reduced growth velocity, height SDS values below -5.5 SDS, a markedly retarded bone age, and delayed puberty. At the age of 12.9 years, growth hormone deficiency (GHD) was diagnosed and treatment with growth hormone was initiated. Our cases emphasize the heterogeneity of symptoms in FA even in siblings with the same genotype. In FA-children with severe growth retardation, GHD must also be considered.

The genetics of Fanconi's anaemia

Fanconi's anaemia (FA) is an inherited bone marrow failure syndrome characterized by considerable clinical and cellular heterogeneity. This has also been recently demonstrated at the genetic and molecular levels following cloning of four out of the seven FA genes. Although this now enables molecular diagnosis in the majority of patients, because of the considerable molecular heterogeneity, the diepoxybutane/mitomycin-C stress test based on the increased chromosomal instability seen in FA cells, compared to normal controls, remains the front-line diagnostic test. This FA cell hallmark has led to the suggestion that FA may represent a defect in DNA repair although the precise function of the cloned FA genes remains unknown. Recent data suggest that they function in a novel cell pathway which has an important role in maintaining chromosome stability. The advances in the genetics of FA have already had some impact on diagnosis--for example, identification of patients with somatic mosaicism who have atypical clinical presentations--but to date they have had little impact on treatment. However, new treatments may now follow; indeed, for a number of reasons, FA may be a good candidate for haemopoietic gene therapy.

The IVS4 + 4 A to T mutation of the Fanconi anemia geneFANCC is not associated with a severe phenotype in Japanese patients

Fanconi anemia (FA) is an autosomal recessive disease characterized by congenital anomalies, aplastic anemia, and a susceptibility to leukemia. There are at least 8 complementation groups (A through H). Extensive analyses of the FA group C gene FANCC in Western countries revealed that 10% to 15% of FA patients have mutations of this gene. The most common mutation is IVS4 + 4 A to T (IVS4), a splice mutation in intron 4, which has been found only in patients of Ashkenazi Jewish ancestry. When we screened 29 Japanese patients (20 unrelated patients and 4 families) using polymerase chain reaction–single strand conformation polymorphism, we found 8 unrelated patients homozygous for IVS4. This is apparently the first non–Ashkenazi-Jewish population for whom this mutation has been detected. The Ashkenazi Jewish patients homozygous for IVS4 have a severe phenotype, in comparison with other FA patients. Our analyses of Japanese patients indicate no significant difference between IVS4 homozygotes and other patients with regard to severity of a clinical phenotype. Thus, ethnic background may have a significant effect on a clinical phenotype in FA patients carrying the same mutation.

Phenotypic correction of Fanconi anemia group C knockout mice

Fanconi anemia (FA) is a genetic disorder characterized by bone marrow failure, congenital anomalies, and a predisposition to malignancy. FA cells demonstrate hypersensitivity to DNA cross-linking agents, such as mitomycin C (MMC). Mice with a targeted disruption of the FANCC gene (fancc −/− nullizygous mice) exhibit many of the characteristic features of FA and provide a valuable tool for testing novel therapeutic strategies. We have exploited the inherent hypersensitivity offancc −/− hematopoietic cells to assay for phenotypic correction following transfer of the FANCC complementary DNA (cDNA) into bone marrow cells. Murine fancc −/− bone marrow cells were transduced with the use of retrovirus carrying the humanfancc cDNA and injected into lethally irradiated recipients. Mitomycin C (MMC) dosing, known to induce pancytopenia, was used to challenge the transplanted animals. Phenotypic correction was determined by assessment of peripheral blood counts. Mice that received cells transduced with virus carrying the wild-type gene maintained normal blood counts following MMC administration. All nullizygous control animals receiving MMC exhibited pancytopenia shortly before death. Clonogenic assay and polymerase chain reaction analysis confirmed gene transfer of progenitor cells. These results indicate that selective pressure promotes in vivo enrichment offancc-transduced hematopoietic stem/progenitor cells. In addition, MMC resistance coupled with detection of the transgene in secondary recipients suggests transduction and phenotypic correction of long-term repopulating stem cells.