Fanconi Anaemia associated with café au lait spots: A rare case report.

Fanconi Anaemia is an autosomal recessive disorder, which is characterised by progressive pancytopenia, café au lait spots (>50%), bruising, petechie, recurrent infections, short height (50%), and thumb and radial bone anomalies (40%). Herein, is presented a case of a lean emaciated female child, who presented with the chief complaints of fever, loose stools and decreased appetite for one month reported at Sindh Government General Hospital, Karachi, on February, 1, 2023. She had cutaneous findings of hyperpigmentation and café au lait spots and a tri-phalangeal thumb. On investigation, pancytopenia and a low reticulocyte count of 0.7% was also observed. Karyotype and chromosomal breakage test induced by Diepoxybutane confirmed her as a case of Fanconi Anaemia.

FANCD2 expression affects platinum response and further characteristics of high grade serous ovarian cancer in cells with different genetic backgrounds.

High-grade serous ovarian cancer (HGSOC) is the most prevalent subtype of ovarian cancer and demonstrates 5-year survival of just 40%. One of the major causes of mortality is the development of tumour resistance to platinum-based chemotherapy, which can be modulated by dysregulation of DNA damage repair pathways. We therefore investigated the contribution of the DNA interstrand crosslink repair protein FANCD2 to chemosensitivity in HGSOC. Increased FANCD2 protein expression was observed in some cell line models of platinum resistant HGSOC compared with paired platinum sensitive models. Knockdown of FANCD2 in some cell lines, including the platinum resistant PEO4, led to increased carboplatin sensitivity. Investigation into mechanisms of FANCD2 regulation showed that increased FANCD2 expression in platinum resistant cells coincides with increased expression of mTOR. Treatment with mTOR inhibitors resulted in FANCD2 depletion, suggesting that mTOR can mediate platinum sensitivity via regulation of FANCD2. Tumours from a cohort of HGSOC patients showed varied nuclear and cytoplasmic FANCD2 expression, however this was not significantly associated with clinical characteristics. Knockout of FANCD2 was associated with increased cell migration, which may represent a non-canonical function of cytoplasmic FANCD2. We conclude that upregulation of FANCD2, possibly mediated by mTOR, is a potential mechanism of chemoresistance in HGSOC and modulation of FANCD2 expression can influence platinum sensitivity and other tumour cell characteristics.

FANCM branchpoint translocase: Master of traverse, reverse and adverse DNA repair.

FANCM is a multifunctional DNA repair enzyme that acts as a sensor and coordinator of replication stress responses, especially interstrand crosslink (ICL) repair mediated by the Fanconi anaemia (FA) pathway. Its specialised ability to bind and remodel branched DNA structures enables diverse genome maintenance activities. Through ATP-powered "branchpoint translocation", FANCM can promote fork reversal, facilitate replication traverse of ICLs, resolve deleterious R-loop structures, and restrain recombination. These remodelling functions also support a role as sensor of perturbed replication, eliciting checkpoint signalling and recruitment of downstream repair factors like the Fanconi anaemia FANCI:FANCD2 complex. Accordingly, FANCM deficiency causes chromosome fragility and cancer susceptibility. Other recent advances link FANCM to roles in gene editing efficiency and meiotic recombination, along with emerging synthetic lethal relationships, and targeting opportunities in ALT-positive cancers. Here we review key properties of FANCM's biochemical activities, with a particular focus on branchpoint translocation as a distinguishing characteristic.

Biallelic FANCA variants detected in sisters with isolated premature ovarian insufficiency.

Premature ovarian insufficiency is a common form of female infertility affecting up to 4% of women and characterised by amenorrhea with elevated gonadotropin before the age of 40. Oocytes require controlled DNA breakage and repair for homologous recombination and the maintenance of oocyte integrity. Biallelic disruption of the DNA damage repair gene, Fanconi anemia complementation group A (FANCA), is a common cause of Fanconi anaemia, a syndrome characterised by bone marrow failure, cancer predisposition, physical anomalies and POI. There is ongoing dispute about the role of heterozygous FANCA variants in POI pathogenesis, with insufficient evidence supporting causation. Here, we have identified biallelic FANCA variants in French sisters presenting with POI, including a novel missense variant of uncertain significance and a likely pathogenic deletion that initially evaded detection. Functional studies indicated no discernible effect on DNA damage sensitivity in patient lymphoblasts. These novel FANCA variants add evidence that heterozygous loss of one allele is insufficient to cause DNA damage sensitivity and POI. We propose that intragenic deletions, that are relatively common in FANCA, may be missed without careful analysis, and could explain the presumed causation of heterozygous variants. Accurate variant curation is critical to optimise patient care and outcomes.

Whole exome sequencing of a novel homozygous missense variant in PALB2 gene leading to Fanconi anaemia complementation group.

Partner and localiser of BRCA2 (PALB2), also known as FANCN, is a key tumour suppressor gene in maintaining genome integrity. Monoallelic mutations of PALB2 are associated with breast and overian cancers, while bi-allelic mutations cause Fanconi anaemia (FA). In the present study, whole exome sequencing (WES) identified a novel homozygous missense variant, NM_024675.3: c.3296C>G (p.Thr1099Arg) in PALB2 gene (OMIM: 610355) that caused FA with mild pulmonary valve stenosis and dysmorphic and atypical features, including lymphangiectasia, non-immune hydrops fetalis and right-sided pleural effusion in a preterm female baby. WES results were further validated by Sanger sequencing. WES improves the screening and detection of novel and causative genetic variants to improve management of disease. To the best of our knowledge, the present study is the first reported FA case in a Saudi family with phenotypic atypical FA features. The results support the role of PALB2 gene and pathogenic variants that may cause clinical presentation of FA. Furthermore, the present results may establish a disease database, providing a groundwork for understanding the key genomic regions to control diseases resulting from consanguinity.

The emergence of Fanconi anaemia type S: a phenotypic spectrum of biallelic BRCA1 mutations.

BRCA1 is involved in the Fanconi anaemia (FA) pathway, which coordinates repair of DNA interstrand cross-links. FA is a rare genetic disorder characterised by bone marrow failure, cancer predisposition and congenital abnormalities, caused by biallelic mutations affecting proteins in the FA pathway. Germline monoallelic pathogenic BRCA1 mutations are known to be associated with hereditary breast/ovarian cancer, however biallelic mutations of BRCA1 were long predicted to be incompatible with embryonic viability, hence BRCA1 was not considered to be a canonical FA gene. Despite this, several patients with biallelic pathogenic BRCA1 mutations and FA-like phenotypes have been identified - defining a new FA type (FA-S) and designating BRCA1 as an FA gene. This report presents a scoping review of the cases of biallelic BRCA1 mutations identified to date, discusses the functional effects of the mutations identified, and proposes a phenotypic spectrum of BRCA1 mutations based upon available clinical and genetic data. We report that this FA-S cohort phenotype includes short stature, microcephaly, facial dysmorphisms, hypo/hyperpigmented lesions, intellectual disability, chromosomal sensitivity to crosslinking agents and predisposition to breast/ovarian cancer and/or childhood cancers, with some patients exhibiting sensitivity to chemotherapy. Unlike most other types of FA, FA-S patients lack bone marrow failure.

The utility of multiple genomic technologies for interpretation of modern next generation sequencing: A novel case of three FANCA gene variants resulting in autosomal recessive Fanconi anaemia.

Fanconi anaemia (FA) is a rare autosomal recessive condition resulting in changes in the FANC gene family. This report describes a case of Fanconi anaemia in a family with complex biallelic variants. The patient is a 32-year-old female diagnosed with FA on cascade testing during childhood with chromosome breakage studies. On examination she had a fixed deformity of the right thumb and the proximal interphalangeal joint was immobile. Her brother shared this radial abnormality and had FA, requiring a bone marrow transplant. She presented in adulthood seeking further BRCA advice and had next generation sequencing that showed three variants in the FANCA gene. One allele a known pathogenic change, the other had two sequence variants in tandem that have been reported as variants of uncertain significance. There is one other unrelated case of these two variants occurring together in cis, resulting in Fanconi anaemia. This case is an interesting example of three variants in the FANCA gene, one allele with a pathogenic deletion and the other with a single complex allele made up of two missense variants of uncertain significance, likely manifesting with FA. It highlights the utility of different genetic technologies in the interpretation of next generation sequencing.

Structural and biochemical basis of interdependent FANCI-FANCD2 ubiquitination.

Di-monoubiquitination of the FANCI-FANCD2 (ID2) complex is a central and crucial step for the repair of DNA interstrand crosslinks via the Fanconi anaemia pathway. While FANCD2 ubiquitination precedes FANCI ubiquitination, FANCD2 is also deubiquitinated at a faster rate than FANCI, which can result in a FANCI-ubiquitinated ID2 complex (IUb D2). Here, we present a 4.1 Å cryo-EM structure of IUb D2 complex bound to double-stranded DNA. We show that this complex, like ID2Ub and IUb D2Ub , is also in the closed ID2 conformation and clamps on DNA. The target lysine of FANCD2 (K561) becomes fully exposed in the IUb D2-DNA structure and is thus primed for ubiquitination. Similarly, FANCI's target lysine (K523) is also primed for ubiquitination in the ID2Ub -DNA complex. The IUb D2-DNA complex exhibits deubiquitination resistance, conferred by the presence of DNA and FANCD2. ID2Ub -DNA, on the other hand, can be efficiently deubiquitinated by USP1-UAF1, unless further ubiquitination on FANCI occurs. Therefore, FANCI ubiquitination effectively maintains FANCD2 ubiquitination in two ways: it prevents excessive FANCD2 deubiquitination within an IUb D2Ub -DNA complex, and it enables re-ubiquitination of FANCD2 within a transient, closed-on-DNA, IUb D2 complex.

Phenotypes of adults with Fanconi anaemia.

The long-term outcomes of adults with Fanconi anaemia (FA) have improved with advances in haematopoietic stem cell transplantation (HSCT) and more detailed follow-up and screening guidelines. The phenotype of those who survive to adulthood may differ from the typical presentation of FA. We collected retrospective clinical data on adults with FA who received their care at the Cincinnati Children's Hospital Medical Center. In our final cohort of 52 patients, there were 29 females and 23 males, with median (range) age of 21 (18-37) years. Overall, 42 patients (81%) were alive at last follow-up. In all, 36 adults (69%) had undergone HSCT, including eight who had developed myelodysplasia or acute myeloid leukaemia. Eight (15%) developed squamous cell carcinoma. Endocrine complications were common, including hypothyroidism (42%), diabetes (10%), low body mass index (31%) and low bone mineral density (51%). The majority of adults with FA were employed (52%) or full-time students (13%). A significant subset of patients with FA are surviving into adulthood without requiring HSCT. Endocrine abnormalities and the development of solid tumours complicate adulthood. With improved survival outcomes following HSCT and more aggressive malignancy screening protocols, ongoing longitudinal analysis will be important to further characterise this cohort and the phenotype of untransplanted adults with FA.

The role of ubiquitin signaling pathway on liver regeneration in rats.

The ubiquitin signalling pathway is a large system associated with numerous intracellular mechanisms. However, its function in the liver regeneration process remains unknown. This particular study investigates the intracellular effect mechanisms of the ubiquitin signalling pathway. It also determines the differences in the expression of 88 genes belonging to the ubiquitin pathway using the RT-PCR array method. To conduct this research, three genes-that differed in the expression analysis were selected. Moreover, their proteins were analysed by western blot analysis while using Ki67 immunohistochemical analysis that determines proliferation rates by hour. It was determined that BRCA1 and BARD1, which are effective in DNA repair, play an active role at PH24. Similarly, Ube2t expression, which belongs to the Fanconi anaemia pathway associated with DNA repair, was also found to be high at PH12-72 h. In addition, it was revealed that the expressions of Anapc2, Anapc11, Cdc20 belonging to the APC/CCdc20 complex, which participate in cell cycle regulation, differed at different hours after PH. Expression of Mul1, which is involved in mitochondrial biogenesis and mitophagy mechanisms, peaked at PH12 under the observation. Considering the Mul1 gene expression difference, MUL1-mediated mitophagy and mitochondrial fission mechanism may be associated with liver regeneration. It was also determined that PARKIN-mediated mitophagy mechanisms are not active in 0-72 h of liver regeneration since PARKIN expression did not show a significant change in PH groups.

To determine the frequency of aldehyde dehydrogenase type 2 (aldh2) deficiency in aplastic anaemia: A single center experience from pakistan.

BACKGROUND: Aplastic anaemia is a rare bone marrow failure syndrome and is defined by pancytopenia associated with a hypo-cellular bone marrow with no increase in reticulin and the absence of any abnormal infiltrate. The objective of the study was to determine the frequency of Aldehyde Dehydrogenase type 2 (ALDH2) deficiency in patients with Aplastic Anaemia and investigate its correlation with patient and disease characteristics. It was a descriptive cross-sectional study conducted at Armed Forces Bone Marrow Transplant Centre Rawalpindi from 01-08-2022-01-02-2023, over 6 months. METHODS: A total of 56 patients who were diagnosed with aplastic anaemia during this period, fulfilling inclusion criteria were enrolled. Patients were genotyped as GG (homozygous) and GA (heterozygous). GG had normal ALDH2, while GA were patients with ALDH2 deficiency. Data was collected on the patient's demographics, type and severity of anaemia, type of hematopoietic stem cell transplant (HSCT) and frequency of ALDH2 deficiency. Results were analyzed for ALDH2 deficiency and its correlation with patient and disease characteristics was investigated. RESULTS: A total of 56 patients were included in the study. The median age of the patients was 28 years (20-39). According to the type of aplastic anaemia, 2 (3.6%) had Fanconi anaemia and 54 (96.4%) had acquired aplastic anaemia. In our study, 18 (32.1%) patients had undergone HSCT while the remaining 38 (67.9%) could not undergo HSCT. The frequency of the presence of ALDH2 deficiency was 2 (3.6%). There was no statistically significant correlation between the frequency of ALDH2 deficiency with variables like gender, age distribution, type of aplastic anaemia, the severity of aplastic anaemia and hematopoietic stem cell transplant. CONCLUSIONS: We concluded from our study the frequency of ALDH2 was rare in patients with aplastic anaemia. There was no statistically significant correlation between the frequency of ALDH2 deficiency with variables like gender, age distribution, type of aplastic anaemia, the severity of aplastic anaemia and hematopoietic stem cell transplant.

Aplastic anemia and paroxysmal nocturnal hemoglobinuria in children and adults in two centers of Northern Greece.

Bone marrow failure (BMF) syndromes are a group of various hematological diseases with cytopenia as a main common characteristic. Given their rarity and continuous progress in the field, we aim to provide data considering the efficiency and safety of the therapeutic methods, focusing on the treatment of aplastic anemia(AA) and paroxysmal nocturnal hemoglobinuria (PNH). We enrolled consecutive patients diagnosed with BMF in two referral centers of Northern Greece from 2008 to 2020. We studied 43 patients with AA (37 adults and 6 children/adolescents) and 6 with classical PNH. Regarding classical PNH, 4 patients have received eculizumab treatment with 1/4 presenting extravascular hemolysis. Among 43 patients with aplastic anemia, PNH clones were detected in 11. Regarding patients that did not receive alloHCT (n=15), 14/15 were treated with ATG and cyclosporine as first line, with the addition of eltrombopag in patients treated after its approval (n=9). With a median follow-up of 16.7 (1.8-56.2) months from diagnosis, 12/14 (85.7%) are alive (4-year OS: 85.1%). AlloHCT was performed in 28 patients. Five patients developed TA-TMA which did not resolve in 3/5 (all with a pre-transplant PNH clone). With the follow-up among survivors reaching 86.3 (6.3-262.4) months, 10-year OS was 56.9%, independently associated with PNH clones after adjusting for age (p=0.024). In conclusion, our real-world experience confirms that novel treatments are changing the field of BMF syndromes. Nevertheless, there is still an unmet need to personalize algorithms in this field.

Irradiation-free, T-cell replete haploidentical transplant for Fanconi anaemia, weighing the benefits.

The optimal haploidentical haematopoietic cell transplant approach for Fanconi anaemia (FA) patients is not well established, given the rarity of the disease, the increased sensitivity to DNA-damaging agents and the high risk of severe graft-versus-host disease (GVHD). The report by Xu et al. suggests that excellent engraftment and short-term survival can be achieved in FA patients without irradiation, but their retrospective cohort was plagued by a high rate of severe GVHD. Our commentary explores the outcomes in T-cell replete haploidentical haematopoietic cell transplant and ponders whether elimination of total body irradiation in FA patients is the best method if it limits the ability to safely administer post-transplant cyclophosphamide. Commentary on: Xu et al. Unmanipulated haploidentical haematopoietic cell transplantation with radiation-free conditioning in Fanconi anaemia: A retrospective analysis from the Chinese Blood and Marrow Transplantation Registry Group. Br J Haematol. 2022;199:401-410.

Unmanipulated haploidentical haematopoietic cell transplantation with radiation-free conditioning in Fanconi anaemia: A retrospective analysis from the Chinese Blood and Marrow Transplantation Registry Group.

Haematopoietic cell transplantation (HCT) is the only curative treatment for haematological complications in patients with Fanconi anaemia (FA). Haploidentical (haplo-) HCT is a promising alternative for FA. We aimed to analyse the outcomes of unmanipulated haplo-HCT in patients with FA with radiation-free conditioning. A total of 56 patients from 11 centres between 2013 and 2021 in China were retrospectively analysed. The mean (SD) cumulative incidence was 96.4% (0.08%) for 30-day neutrophil engraftment and 85.5% (0.24%) for 100-day platelet engraftment. With a median (range) follow-up of 2.4 (0.2-5.8) years, favourable mean (SD) overall survival of 80.9% (5.5%) and event-free survival of 79.3% (5.6%) were achieved. The mean (SD) incidences of acute graft-versus-host disease (aGvHD) Grade II-IV and Grade III-IV were 55.4% (0.45%) and 42.9 (0.45%) respectively. The mean (SD) cumulative incidence of 3-year chronic graft-versus-host disease (cGvHD) was 34.7% (0.86%) and that of moderate-to-severe cGvHD was 9.0% (0.19%). Our data demonstrate that in unmanipulated haplo-HCT for patients with FA, radiation-free regimens based on fludarabine and low-dose cyclophosphamide ± busulfan achieved favourable engraftment and survival with relatively high incidences of aGvHD and cGvHD. These results prompt the use of low-intensity conditioning without radiation and intensive GvHD prophylaxis when considering unmanipulated haplo-HCT in patients with FA.

Mutated FANCA Gene Role in the Modulation of Energy Metabolism and Mitochondrial Dynamics in Head and Neck Squamous Cell Carcinoma.

Fanconi Anaemia (FA) is a rare recessive genetic disorder characterized by a defective DNA repair mechanism. Although aplastic anaemia is the principal clinical sign in FA, patients develop a head and neck squamous cell carcinoma (HNSCC) with a frequency 500-700 folds higher than the general population, which appears more aggressive, with survival of under two years. Since FA gene mutations are also associated with a defect in the aerobic metabolism and an increased oxidative stress accumulation, this work aims to evaluate the effect of FANCA mutation on the energy metabolism and the relative mitochondrial quality control pathways in an HNSCC cellular model. Energy metabolism and cellular antioxidant capacities were evaluated by oximetric, luminometric, and spectrophotometric assays. The dynamics of the mitochondrial network, the quality of mitophagy and autophagy, and DNA double-strand damage were analysed by Western blot analysis. Data show that the HNSCC cellular model carrying the FANCA gene mutation displays an altered electron transport between respiratory Complexes I and III that does not depend on the OxPhos protein expression. Moreover, FANCA HNSCC cells show an imbalance between fusion and fission processes and alterations in autophagy and mitophagy pathways. Together, all these alterations associated with the FANCA gene mutation cause cellular energy depletion and a metabolic switch to glycolysis, exacerbating the Warburg effect in HNSCC cells and increasing the growth rate. In addition, the altered DNA repair due to the FANCA mutation causes a higher accumulation of DNA damage in the HNSCC cellular model. In conclusion, changes in energy metabolism and mitochondrial dynamics could explain the strict correlation between HNSCC and FA genes, helping to identify new therapeutic targets.

The incidence and spectrum of congenital hand differences in patients with Fanconi anaemia: analysis of 48 patients.

We analysed the spectrum of congenital hand differences in a cohort of patients with Fanconi anaemia (FA). Data of 48 FA patients at the National Cancer Institute were reviewed focusing on age at diagnosis, type and severity of limb difference and any potential association with other known clinical anomalies that are part of the FA phenotype, specifically VACTERL-H and PHENOS. Twenty-eight patients had an upper limb difference, which always included thumb hypoplasia. Twenty-three patients had bilateral upper limb differences, including varying combinations and severities of thumb hypoplasia, radial dysplasia and thumb duplication. Patients with a limb difference were diagnosed at a younger age (<2 years: 15/28 with limb anomaly versus 4/20 without a limb anomaly). However, 7/28 with limb anomalies, usually thumb hypoplasia, were not diagnosed until after 6 years of age. This study demonstrates the broad spectrum of radial ray anomalies within the FA phenotype along with the possibility of either unilateral or bilateral upper limb differences and adds further merit to consideration of screening for FA in all cases of radial ray anomaly.Level of evidence: II.

Fanconi anaemia: A syndrome with distinct subgroups.

Fanconi anaemia (FA) is an inherited bone marrow failure syndrome (IBMFS) with a high cancer predisposition rate. Traditional diagnoses are made before age 10 years due to bone marrow failure (BMF) and characteristic birth defects. Up to 10% of published cases were adults at diagnosis. We hypothesized that FA subgroups diagnosed in childhood are distinct from those diagnosed as adults. We classified patients by age at diagnosis of FA as FA-PED (<18 years) or FA-ADULT (≥18 years). The National Cancer Institute IBMFS cohort included 178 FA-PED and 26 FA-ADULT cases. We compared various features; the cumulative incidences of first adverse events (severe BMF leading to haematopoietic cell transplant or death, leukaemia, or solid tumours) were compared using competing-risk analyses. FA-ADULT lacked the 'typical' FA features (birth defects and early-onset BMF or leukaemia), were mainly female, had more patients with FANCA genotype, and had or developed more head and neck squamous-cell carcinoma (HNSCC) and/or gynaecological cancers compared with FA-PED, albeit at similar ages in both subgroups. FA-ADULT is a distinct subgroup that remained unrecognized during childhood. Centres for adult haematology-oncology should consider FA diagnosis in patients with early-onset HNSCC or gynaecological cancer with or without haematologic problems.

Extensive Lower Lip Squamous Cell Carcinoma in a Fanconi Anaemia Patient and Treatment Delays during COVID-19 Pandemic.

Fanconi anaemia (FA) is an autosomal recessive inherited disease that renders patients susceptible to congenital anomalies, bone marrow failures, leukaemia, and solid malignancies. FA is caused by the loss of function of at least one gene in the FA/BRCA biological pathway, which is involved in DNA repair. Patients with FA have an increased risk of developing head and neck cancer, particularly oral squamous cell carcinoma (SCC). Due to susceptibility of head and neck cancer at a very young age, relatively poor survival rate, low tolerance to oncologic interventions, and complexity of treatments, strict follow-up is mandatory to detect any changes or recurrence of SCC in the head and neck region in FA patients. Surgery is the mainstay of treatment, but adjuvant therapy should be instituted when needed. This short report describes a rare case of lower lip SCC in FA and its management. It also highlights the impact of the COVID-19 pandemic on healthcare practices.

The impact of clonal diversity and mosaicism on haematopoietic function in Fanconi anaemia.

Recent advances have facilitated studies of the clonal architecture of the aging haematopoietic system, and provided clues to the mechanisms underlying the origins of hematopoietic malignancy. Much less is known about the clonal composition of haematopoiesis and its impact in bone marrow failure (BMF) disorders, including Fanconi anaemia (FA). Understanding clonality in FA is likely to inform both the marked predisposition to cancer and the rapid erosion of regenerative reserve seen with this disease. This may also hold broader lessons for haematopoietic stem cell biology in other diseases with a clonal restriction. In this review, we focus on the conceptual basis and available tools to study clonality, and highlight insights in somatic mosaicism and malignant evolution in FA in the context of haematopoietic failure and gene therapy.

A functionally impaired missense variant identified in French Canadian families implicates FANCI as a candidate ovarian cancer-predisposing gene.

BACKGROUND: Familial ovarian cancer (OC) cases not harbouring pathogenic variants in either of the BRCA1 and BRCA2 OC-predisposing genes, which function in homologous recombination (HR) of DNA, could involve pathogenic variants in other DNA repair pathway genes. METHODS: Whole exome sequencing was used to identify rare variants in HR genes in a BRCA1 and BRCA2 pathogenic variant negative OC family of French Canadian (FC) ancestry, a population exhibiting genetic drift. OC cases and cancer-free individuals from FC and non-FC populations were investigated for carrier frequency of FANCI c.1813C>T; p.L605F, the top-ranking candidate. Gene and protein expression were investigated in cancer cell lines and tissue microarrays, respectively. RESULTS: In FC subjects, c.1813C>T was more common in familial (7.1%, 3/42) than sporadic (1.6%, 7/439) OC cases (P = 0.048). Carriers were detected in 2.5% (74/2950) of cancer-free females though female/male carriers were more likely to have a first-degree relative with OC (121/5249, 2.3%; Spearman correlation = 0.037; P = 0.011), suggesting a role in risk. Many of the cancer-free females had host factors known to reduce risk to OC which could influence cancer risk in this population. There was an increased carrier frequency of FANCI c.1813C>T in BRCA1 and BRCA2 pathogenic variant negative OC families, when including the discovery family, compared to cancer-free females (3/23, 13%; OR = 5.8; 95%CI = 1.7-19; P = 0.005). In non-FC subjects, 10 candidate FANCI variants were identified in 4.1% (21/516) of Australian OC cases negative for pathogenic variants in BRCA1 and BRCA2, including 10 carriers of FANCI c.1813C>T. Candidate variants were significantly more common in familial OC than in sporadic OC (P = 0.04). Localization of FANCD2, part of the FANCI-FANCD2 (ID2) binding complex in the Fanconi anaemia (FA) pathway, to sites of induced DNA damage was severely impeded in cells expressing the p.L605F isoform. This isoform was expressed at a reduced level, destabilized by DNA damaging agent treatment in both HeLa and OC cell lines, and exhibited sensitivity to cisplatin but not to a poly (ADP-ribose) polymerase inhibitor. By tissue microarray analyses, FANCI protein was consistently expressed in fallopian tube epithelial cells and only expressed at low-to-moderate levels in 88% (83/94) of OC samples. CONCLUSIONS: This is the first study to describe candidate OC variants in FANCI, a member of the ID2 complex of the FA DNA repair pathway. Our data suggest that pathogenic FANCI variants may modify OC risk in cancer families.