Chronic Granulomatous Disease with the McLeod Phenotype: a French National Retrospective Case Series.

BACKGROUND: X-linked chronic granulomatous disease (CGD) is a primary immunodeficiency caused by mutations in the CYBB gene (located on Xp21.1). Patients with large deletions on chromosome Xp21.1 can present with the McLeod phenotype and also Duchenne muscular dystrophy or retinitis pigmentosa. The objective of the present study was to describe a series of French patients with CGD and the McLeod phenotype. METHODS: We retrospectively collected data from the medical records of 8 patients with CGD and the McLeod phenotype registered at the French National Reference Center for blood types. RESULTS: The median age at diagnosis of CGD was 1.2 years, the median age at diagnosis of the McLeod phenotype was 4.5 years, and the median length of follow-up was 15.2 years. Four patients displayed allo-immunization, with anti-KEL20 and anti-XK1 (formerly known as anti-KL) antibodies. Five of the 6 patients with available blood smears had acanthocytosis. Neuropsychiatric, muscle-related, and ocular manifestations were present in 4, 2, and 1 of the patients, respectively. Three of the 4 patients having undergone allogeneic hematopoietic stem cell transplantation (HSCT) are alive. Overall, 5 patients are alive, and 3 are alive and well. CONCLUSION: This is the largest yet descriptive study of a series of patients with X-linked CGD and the McLeod phenotype. Although this disease combination is rare, the timely, accurate diagnosis of the McLeod phenotype is critical because of the serious post-transfusion complications. However, HSCT can be considered in these patients.

Pediatric randomized trial EORTC CLG 58951: Outcome for adolescent population with acute lymphoblastic leukemia.

Over the years, the prognosis of adolescents treated for acute lymphoblastic leukemia (ALL) has improved. However, this age group still represents a challenge with an overall survival (OS) of 60% compared to 85% in younger children. Herein, we report the outcome of adolescents treated in the European Organisation for Research and Treatment of Cancer (EORTC) 58951 clinical trial. EORTC 58951 clinical trial included patients with de novo ALL between 1998 and 2008. For this study, we analyzed data of all adolescents between 15 and under 18. Data from 97 adolescents were analyzed, 70 had B-lineage and 27 had T-lineage ALL. The 8-year event-free survival (EFS) and OS for the B-cell precursor ALL cases were 72.3% (59.4%-81.7%) and 80.8% (67.4%-89.1%), respectively. For the T-lineage, the 8-year EFS and OS were 57.4% (36.1%-74.0%) and 59.0% (36.1%-76.2%), respectively. "B-other" ALL, defined as BCP-ALL lacking any known recurrent genetic abnormalities were more frequent in our adolescent population (52.8%) than in younger children (27.1%). Outcome of adolescents in the EORTC 58951 study is supporting the findings that adolescents have better outcome in pediatric compared to adults' trials. Nevertheless, in pediatric studies, adolescents still have a worse prognosis than younger children. Despite the fact that specific unfavorable characteristics may be linked to the adolescent population, a careful study and characterization of adolescents "B-other" genetic abnormalities in ALL is critical to improve the outcome of this population.

Identification of new F8 deep intronic variations in patients with haemophilia A.

INTRODUCTION: With current molecular diagnosis, about 1 to 5% of haemophilia A (HA) patients remain genetically unresolved. In these cases, deep intronic variation or structural variation disrupting the F8 gene could be causal. AIM: To identify the causal variation in four genetically unresolved mild-to-severe HA patients using an F8 mRNA analysis approach. METHODS: Ectopic F8 mRNA analysis was performed in four unrelated HA patients. An in vitro minigene assay was performed in order to confirm the deleterious splicing impact of each variation identified. RESULTS: In all probands, mRNA analysis revealed an aberrant splicing pattern, and sequencing of the corresponding intronic region found a deep intronic substitution. Two of these were new variations: c.2113+601G>A and c.1443+602A>G, while the c.143+1567A>G, found in two patients, has previously been reported. The c.1443+602A>G and the c.143+1567A>G variants both led to the creation of a de novo acceptor or donor splice site, respectively. Moreover, the c.143+1567A>G was found in 3/6 patients with genetically unresolved moderate HA registered in our laboratory. Haplotype analysis performed in all patients carrying the c.143+1567A>G variation suggests that this variation could be a recurrent variation. The c.2113+601G>A led to the exonization of a 122-bp antisense AluY element by increasing the strength of a pre-existing cryptic 5' splice site. For each point variation, in vitro splicing analysis confirmed its deleterious impact on splicing of the F8 transcript. CONCLUSION: We identified three deep intronic variations, leading to an aberrant mRNA splicing process as HA causing variation.

Impact of detectable measurable residual disease on umbilical cord blood transplantation.

The impact of measurable residual disease (MRD) on cord blood transplantation (CBT) outcomes has remained debated. To address this issue, we assessed the impact of measurable MRD at CBT on outcomes in large cohort of patients with acute leukemia. Inclusion criteria included adult patients with acute myeloid (AML) or acute lymphoblastic leukemia (ALL), CBT as first allo-HCT in first or second complete remission (CR) at transplantation, and known MRD status at the time of CBT. Data from 506 patients were included in the analysis. Among them, 317 patients had AML and 189 had ALL. Positive MRD was reported in 169 (33%) patients while the remaining 337 patients were MRD negative at CBT. At 2 years, relapse incidence was 18% in patients with MRD negativity vs 33% in those with MRD positivity at transplantation (P < .001). Two-year leukemia-free survival (LFS) and overall survival (OS) were 57% and 60%, respectively, in MRD negative patients, vs 38% (P < .001) and 48% (P = .004), respectively, in those with MRD positivity. There was no interaction between the impact of MRD on OS and LFS and diagnosis (ie, ALL vs AML), single or double CBT, and reduced-intensity or myeloablative conditioning. On multivariate analysis, MRD positivity was associated with a higher risk of relapse (HR = 1.8, P = .003), comparable non-relapse mortality (P = .44), worse LFS (HR = 1.4, P = .008) and a trend towards worse OS (HR = 1.3, P = .065). In conclusion, these data suggest that novel strategies that are aiming to achieve MRD negativity at CBT are needed for leukemic patients with positive MRD pre-CBT.

Outcomes of Salvage Haploidentical Transplant with Post-Transplant Cyclophosphamide for Rescuing Graft Failure Patients: a Report on Behalf of the Francophone Society of Bone Marrow Transplantation and Cellular Therapy.

Prognosis of patients with graft failure is dismal, and retransplantation is the sole option for long-term survival. To address the interest of haploidentical transplantation as a salvage option in this context, we analyzed data from 24 patients with graft failure or loss retransplanted with a haploidentical donor who received post-transplant cyclophosphamide (PTCy) as graft-versus-host disease prophylaxis (GVHD). Fludarabine-based reduced-intensity conditioning was used in 23 patients and the Baltimore regimen in 14 patients. The median delay between previous and salvage transplantation for graft failure was 63 days (range, 39 to 98). In addition to PTCy, all patients received cyclosporine, and 22 patients also received mycophenolate mofetil for GVHD prophylaxis. With a median follow-up of 353 days (range, 16 to 2010), 1-year overall survival (OS) was 56% (95% confidence interval, 38% to 81%). Transplant complications accounted for 80% of deaths. The cumulative incidence of neutrophil engraftment at day +30 was 79%. Cumulative incidence of grades II to IV acute GVHD at day 100 was 14%, and 1-year cumulative incidence of chronic GVHD was 31%. One-year cumulative incidence of relapse was 13%. Stem cell source did not impact on engraftment, GVHD, relapse, or OS. Salvage haploidentical transplant with PTCy for rescuing graft failure patients leads to an acceptable 1-year OS and might be a valid option in this poor situation.

Comparison of Dynamic International Prognostic Scoring System and MYelofibrosis SECondary to PV and ET Prognostic Model for Prediction of Outcome in Polycythemia Vera and Essential Thrombocythemia Myelofibrosis after Allogeneic Stem Cell Transplantation.

We aimed to validate the MYelofibrosis SECondary to PV and ET prognostic model (MYSEC-PM) in 159 patients with myelofibrosis secondary to polycythemia vera (PV) and essential thrombocythemia (ET) from the European Society for Blood and Marrow Transplantation registry undergoing transplantation from matched siblings or unrelated donors. Furthermore, we aimed to test its prognostic performance in comparison with the Dynamic International Prognostic Scoring System (DIPSS). Score performance was analyzed using the concordance index (C): the probability that a patient who experienced an event had a higher risk score than a patient who did not (C > .5 suggesting predictive ability). Median follow-up of the total cohort was 41 months (range, 34 to 54), 45 months in post-PV and 38 months in post-ET myelofibrosis. Survival at 1, 2, and 4 years was 70% (95% CI, 63% to 77%), 61% (95% CI, 53% to 69%), and 52% (95% CI, 43% to 61%) for the total cohort; 70% (95% CI, 59% to 80%), 61% (95% CI, 49% to 73%), and 51% (95% CI, 38% to 64%) for post-PV; and 71% (95% CI, 61% to 81%), 61% (95% CI, 50% to 72%), and 54% (95% CI, 42% to 66%) for post-ET myelofibrosis (P = .78). Overall, the DIPSS was not significantly predictive of outcome (P = .28). With respect to the MYSEC-PM, overall survival at 4 years was 69% for the low-risk, 55% for the intermediate 1-risk, 47% for the intermediate 2-risk, and 22% (0% to 45%) for the high-risk groups. The prognostic model was predictive of survival overall (P = .05), whereas groups with intermediate 2 and high risk showed no significant difference (P = .44). Assessment of prognostic utility yielded a C-index of .575 (95% CI, .502 to .648) for the DIPSS, whereas assessment of the MYSEC-PM resulted in a C-statistics of .636 (95% CI, .563 to .708), indicating improvement in prediction of post-transplant survival using the new MYSEC-PM. In addition, transplantations from an unrelated donor in comparison with an HLA-identical sibling showed worse outcome (P = .04), and transplant recipients seropositive for cytomegalovirus in comparison with seronegative recipients (P = .01) showed worse survival. In conclusion, incorporating transplant-specific and clinical and mutational information together with the MYSEC-PM may enhance risk stratification.

Safety and efficacy of allogeneic hematopoietic stem cell transplant after PD-1 blockade in relapsed/refractory lymphoma.

Anti-programmed cell death protein 1 (PD-1) monoclonal antibodies are being increasingly tested in patients with advanced lymphoma. Following treatment, many of those patients are likely to be candidates for allogeneic hematopoietic stem cell transplant (HSCT). However, the safety and efficacy of HSCT may be affected by prior PD-1 blockade. We conducted an international retrospective analysis of 39 patients with lymphoma who received prior treatment with a PD-1 inhibitor, at a median time of 62 days (7-260) before HSCT. After a median follow-up of 12 months, the 1-year cumulative incidences of grade 2-4 and grade 3-4 acute graft-versus-host disease (GVHD) were 44% and 23%, respectively, whereas the 1-year incidence of chronic GVHD was 41%. There were 4 treatment-related deaths (1 from hepatic sinusoidal obstruction syndrome, 3 from early acute GVHD). In addition, 7 patients developed a noninfectious febrile syndrome shortly after transplant requiring prolonged courses of steroids. One-year overall and progression-free survival rates were 89% (95% confidence interval [CI], 74-96) and 76% (95% CI, 56-87), respectively. One-year cumulative incidences of relapse and nonrelapse mortality were 14% (95% CI, 4-29) and 11% (95% CI, 3-23), respectively. Circulating lymphocyte subsets were analyzed in 17 patients. Compared with controls, patients previously treated with PD-1 blockade had significantly decreased PD-1+ T cells and decreased ratios of T-regulatory cells to conventional CD4 and CD8 T cells. In conclusion, HSCT after PD-1 blockade appears feasible with a low rate of relapse. However, there may be an increased risk of early immune toxicity, which could reflect long-lasting immune alterations triggered by prior PD-1 blockade.

Acadesine Circumvents Azacitidine Resistance in Myelodysplastic Syndrome and Acute Myeloid Leukemia.

Myelodysplastic syndrome (MDS) defines a group of heterogeneous hematologic malignancies that often progresses to acute myeloid leukemia (AML). The leading treatment for high-risk MDS patients is azacitidine (Aza, Vidaza®), but a significant proportion of patients are refractory and all patients eventually relapse after an undefined time period. Therefore, new therapies for MDS are urgently needed. We present here evidence that acadesine (Aca, Acadra®), a nucleoside analog exerts potent anti-leukemic effects in both Aza-sensitive (OCI-M2S) and resistant (OCI-M2R) MDS/AML cell lines in vitro. Aca also exerts potent anti-leukemic effect on bone marrow cells from MDS/AML patients ex-vivo. The effect of Aca on MDS/AML cell line proliferation does not rely on apoptosis induction. It is also noteworthy that Aca is efficient to kill MDS cells in a co-culture model with human medullary stromal cell lines, that mimics better the interaction occurring in the bone marrow. These initial findings led us to initiate a phase I/II clinical trial using Acadra® in 12 Aza refractory MDS/AML patients. Despite a very good response in one out 4 patients, we stopped this trial because the highest Aca dose (210 mg/kg) caused serious renal side effects in several patients. In conclusion, the side effects of high Aca doses preclude its use in patients with strong comorbidities.

Cord Blood Unit Dominance Analysis and Effect of the Winning Unit on Outcomes after Double-Unit Umbilical Cord Blood Transplantation in Adults with Acute Leukemia: A Retrospective Study on Behalf of Eurocord, the Cord Blood Committee of Cellular Therapy, Immunobiology Working Party, and the Acute Leukemia Working Party of the European Group for Blood and Marrow Transplantation.

Usually, after double umbilical cord blood transplantation (DUCBT), only 1 of the transplanted units persists in the long term. The characteristics of the winning cord blood unit (W-CBU) that determine unit dominance and how they influence the outcomes of DUCBT remain unclear. We retrospectively analyzed 347 patients with acute leukemia transplanted with a DUCBT (694 CBU) from 2005 to 2013 who had documented neutrophil engraftment and a W-CBU identified by chimerism analysis, to identify unit characteristics impacting on dominance. Median age at DUCBT was 40 years and median follow-up was 35 months. Among W-CBUs, 41% were ≥5/6 HLA matched to the recipient and 59% were ≤4/6. Multivariate analysis indicated that ≤4/6 HLA-matched W-CBUs led to lower leukemia-free survival (44% versus 56%; hazard ratio [HR], 1.5; P = .032) and overall survival (49% versus 62%; HR, 1.5; P = .028), increased nonrelapse mortality (26% versus 18%; HR, 1.9; P = .027), and acute graft-versus-host disease (46% versus 35%; HR, 1.7; P = .013). We were unable to predict unit dominance, but we demonstrated that outcomes were strongly influenced by the degree of HLA mismatch between W-CBU and recipient. Therefore, selection of both units with the lower number of HLA mismatches with the recipient is indicated.

An effective modestly intensive re-induction regimen with bortezomib in relapsed or refractory paediatric acute lymphoblastic leukaemia.

This trial explored the efficacy of re-induction chemotherapy including bortezomib in paediatric relapsed/refractory acute lymphoblastic leukaemia. Patients were randomized 1:1 to bortezomib (1.3 mg/m2 /dose) administered early or late to a dexamethasone and vincristine backbone. Both groups did not differ regarding peripheral blast count on day 8, the primary endpoint. After cycle 1, 8 of 25 (32%) patients achieved complete remission with incomplete blood count recovery, 7 (28%) a partial remission and 10 had treatment failure. Most common grade 3-4 toxicities were febrile neutropenia (31%) and pain (17%). Bortezomib was safely combined with vincristine. Bortezomib rarely penetrated the cerebrospinal fluid.

Late effects after hematopoietic stem cell transplantation for ß-thalassemia major: the French national experience.

In this retrospective study, we evaluate long-term complications in nearly all ß-thalassemia-major patients who successfully received allogeneic hematopoietic stem cell transplantation in France. Ninety-nine patients were analyzed with a median age of 5.9 years at transplantation. The median duration of clinical follow up was 12 years. All conditioning regimens were myeloablative, most were based on busulfan combined with cyclophosphamide, and more than 90% of patients underwent a transplant from a matched sibling donor. After transplantation, 11% of patients developed thyroid dysfunction, 5% diabetes, and 2% heart failure. Hypogonadism was present in 56% of females and 14% of males. Female patients who went on to normal puberty after transplant were significantly younger at transplantation than those who experienced delayed puberty (median age 2.5 vs 8.7 years). Fertility was preserved in 9 of 27 females aged 20 years or older and 2 other patients became pregnant following oocyte donation. In addition to patient's age and higher serum ferritin levels at transplantation, time elapsed since transplant was significantly associated with decreased height growth in multivariate analysis. Weight growth increased after transplantation particularly in females, 36% of adults being overweight at last evaluation. A comprehensive long-term monitoring, especially of endocrine late effects, is required after hematopoietic stem cell transplantation for thalassemia.

Acute Myeloid Leukemia With Central Nervous System Involvement in Children: Experience From the French Protocol Analysis ELAM02.

Central nervous system (CNS) involvement at diagnosis of pediatric acute myeloid leukemia (AML) is not considered as an independent prognostic factor. This study describes the prognostic value of pediatric AML with CNS involvement at diagnosis. Pediatric patients were treated for de novo AML in the French multicenter trial ELAM02. Lumbar puncture was carried out in the first week, and the treatment was adapted to the CNS status. No patient received CNS radiotherapy. The patients were classified into 2 groups: CNS+ and CNS-. Of the 438 patients, 16% (n=70) had CNS involvement at diagnosis, and 29% showed clinical signs. The patients with CNS disease were younger (40% were below 2 y old), had a higher white blood cell count (median of 45 vs. 13 G/L), and had M4 and M5 morphologies. The complete remission rate was similar at 92.8% for CNS+ and 88.5% for CNS-. There was no significant difference between the CNS+ and the CNS- group in overall survival (76% and 71%, respectively) and event-free survival (57% and 52%, respectively). Regarding the occurrence of first relapse, the CNS+ group had a higher combined relapse rate of 26.1% compared with 10% for the CNS- group. The results indicate that CNS involvement at diagnosis of pediatric AML is not an independent prognostic factor. Triple intrathecal chemotherapy combined with high-dose intravenous cytarabine should be the first-line treatment for CNS disease.

Management of Myelodysplastic Syndrome Relapsing after Allogeneic Hematopoietic Stem Cell Transplantation: A Study by the French Society of Bone Marrow Transplantation and Cell Therapies.

To find out prognostic factors and to investigate different therapeutic approaches, we report on 147 consecutive patients who relapsed after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for myelodysplastic syndrome (MDS). Sixty-two patients underwent immunotherapy (IT group, second allo-HSCT or donor lymphocyte infusion), 39 received cytoreductive treatment alone (CRT group) and 46 were managed with palliative/supportive cares (PSC group). Two-year rates of overall survival (OS) were 32%, 6%, and 2% in the IT, CRT, and PSC groups, respectively (P < .001). In multivariate analysis, 4 factors adversely influenced 2-year rates of OS: history of acute graft-versus-host disease (hazard ratio [HR], 1.83; 95% confidence interval [CI], 1.26 to 2.67; P = .002), relapse within 6 months (HR, 2.69; 95% CI, .82 to 3.98; P < .001), progression to acute myeloid leukemia (HR, 2.59; 95% CI, 1.75 to 3.83; P < .001), and platelet count < 50 G/L at relapse (HR, 1.68; 95% CI, 1.15 to 2.44; P = .007). A prognostic score based on those factors discriminated 2 risk groups with median OSs of 13.2 versus 2.4 months, respectively (P < .001). When propensity score, prognostic score, and treatment strategy were included in Cox model, immunotherapy was found to be an independent factor that favorably impacts OS (HR, .40; 95% CI, .26 to .63; P < .001). In conclusion, immunotherapy should be considered when possible for MDS patients relapsing after allo-HSCT.

Outcomes of unrelated cord blood transplantation in patients with multiple myeloma: a survey on behalf of Eurocord, the Cord Blood Committee of Cellular Therapy and Immunobiology Working Party, and the Chronic Leukemia Working Party of the EBMT.

Although allogeneic stem cell transplantation is not a standard therapy for multiple myeloma, some patients can benefit from this intense therapy. There are few reports on outcomes after umbilical cord blood transplantation in multiple myeloma, and investigation of this procedure is warranted. We retrospectively analyzed 95 patients, 85 with multiple myeloma and 10 with plasma cell leukemia, receiving single or double umbilical cord blood transplantation from 2001 to 2013. Median follow up was 41 months. The majority of patients received a reduced intensity conditioning. The cumulative incidence of neutrophil engraftment was 97%±3% at 60 days, and that of 100-day acute graft-versus-host disease grade II-IV was 41%±5%. Chronic graft-versus-host disease at two years was 22%±4%. Relapse and non-relapse mortality was 47%±5% and 29%±5% at three years, respectively. Three-year progression-free survival and overall survival were 24%±5% and 40%±5%, respectively. Anti-thymocyte globulin was associated with decreased incidence of acute graft-versus-host disease, higher non-relapse mortality, decreased overall and progression-free survival. Patients with high cytogenetic risk had higher relapse, and worse overall and progression-free survival. In conclusion, umbilical cord blood transplantation is feasible for multiple myeloma patients.

Impact of eculizumab treatment on paroxysmal nocturnal hemoglobinuria: a treatment versus no-treatment study.

Intravascular hemolysis in Paroxysmal nocturnal hemoglobinuria (PNH) can effectively be controlled with eculizumab, a humanized monoclonal antibody that binds complement protein C5. We report here a retrospective comparison study between 123 patients treated with eculizumab in the recent period (>2005) and 191 historical controls (from the French registry). Overall survival (OS) at 6 years was 92% (95%CI, 87 to 98) in the eculizumab cohort versus 80% (95%CI 70 to 91) in historical controls diagnosed after 1985 (HR 0.38 [0.15 to 0.94], P = 0.037). There were significantly fewer thrombotic events (TEs) in the group of patients treated with eculizumab (4% [1-10]) as compared to the historical cohort (27% [20-34]). However, we found that TEs may still occur after the initiation of eculizumab treatment and that previous TEs still have a negative impact on survival. Evolutions to myelodysplastic syndrome or acute leukemia were similar in both cohorts. There was less evolution to aplastic anemia in the treatment group. In multivariate analysis, absence of a previous TE and treatment with eculizumab were associated with a better OS. Treatment with eculizumab improves overall survival in classic PNH patients without increasing the risk of clonal evolution.

CD20 alternative splicing isoform generates immunogenic CD4 helper T epitopes.

Cancer-specific splice variants gain significant interest as they generate neo-antigens that could be targeted by immune cells. CD20, a membrane antigen broadly expressed in mature B cells and in B cell lymphomas, is subject to an alternative splicing named D393-CD20 leading to loss of membrane expression of the spliced isoform. D393-CD20 expression is detectable in transformed B cells and upregulated in various lymphoma B cells. In this study, we show that D393-CD20 is translated in malignant B cells and that D393-CD20 specific CD4 T cells producing IFN-γ are present in B-cell lymphoma patients. Then, we have investigated whether the 20mer D393-CD20 peptide spanning the splicing site might be targeted by the immune system and we have shown that D393-CD20-specific CD4 Th1 clones could directly recognize malignant B cell lines and kill autologous lymphoma B cells indicating that D393-CD20-derived epitopes are naturally processed and presented on tumor cells. Finally, D393-CD20 peptide-based vaccination induced specific CD8 and CD4 T cell responses in HLA-humanized transgenic mice suggesting the presentation of D393-CD20 derived peptides on both HLA Class-I and -II. These findings support further investigations on the potential use of D393-CD20 directed specific immunotherapy in B cell malignancies.

Whole F8 gene sequencing identified pathogenic structural variants in the remaining unsolved patients with severe hemophilia A.

BACKGROUND: No F8 genetic abnormality is detected in approximately 1% to 2% of patients with severe hemophilia A (HA) using conventional genetic approaches. In these patients, deep intronic variation or F8 disrupting genomic rearrangement could be causal. OBJECTIVES: The study aimed to identify the causal variation in families with a history of severe HA for whom genetic investigations failed. METHODS: We performed whole F8 gene sequencing in 8 propositi. Genomic rearrangements were confirmed by Sanger sequencing of breakpoint junctions and/or quantitative polymerase chain reaction. RESULTS: A structural variant disrupting F8 was found in each propositus, so that all the 815 families with a history of severe HA registered in our laboratory received a conclusive genetic diagnosis. These structural variants consisted of 3 balanced inversions, 3 large insertions of gained regions, and 1 retrotransposition of a mobile element. The 3 inversions were 105 Mb, 1.97 Mb, and 0.362 Mb in size. Among the insertions of gained regions, one corresponded to the insertion of a 34 kb gained region from chromosome 6q27 in F8 intron 6, another was the insertion of a 447 kb duplicated region from chromosome 9p22.1 in F8 intron 14, and the last one was the insertion of an Xq28 349 kb gained in F8 intron 5. CONCLUSION: All the genetically unsolved cases of severe HA in this cohort were due to structural variants disrupting F8. This study highlights the effectiveness of whole F8 sequencing to improve the molecular diagnosis of HA when the conventional approach fails.