Severe and moderate haemophilia A and B in US females

Bleeding phenotype according to factor level in 825 children with nonsevere hemophilia: data from the PedNet cohort

BACKGROUND

Information on bleeding phenotype in nonsevere hemophilia may be used to determine target factor levels for prophylaxis or gene therapy in severe hemophilia.

OBJECTIVES

To assess the association between endogenous factor level and bleeding phenotype in children with nonsevere (factor [F]VIII/FIX activity 1%-25%) hemophilia A (HA) and B without prophylaxis.

METHODS

Data on annualized bleeding rate (ABR), annualized joint bleeding rate (AJBR), and onset of bleeding were extracted from the international PedNet cohort including children born since 2000. Mean ABR and AJBR were modeled and compared according to FVIII/FIX endogenous activity (1%-2%, 3%-5%, 6%-10%, 11%-15%, 16%-20%, and 21%-25%) using negative binomial regression. Onset of bleeding was analyzed using Kaplan-Meier survival curves.

RESULTS

Eight hundred twenty-five children (40% with moderate hemophilia; 87% with HA) with median follow-up of 7.4 years/child were included. The median age at onset of bleeding and median bleeding rates changed with increasing endogenous activity. From endogenous FVIII 1% to 2% to 21% to 25%, the age at onset of bleeding changed from a median of 1.4 to 14.2 years, ABR from 1.6 to 0.1/y, and AJBR from 0.5 to 0.0/y. From endogenous FIX 1% to 2% to 16% to 25%, the onset of bleeding changed from a median of 1.7 to 6.1 years, ABR from 0.5 to 0.1/y, and AJBR from 0.1 to 0.0/y. The negative correlation between AJBR and factor level was most strongly pronounced up to a factor level of 6% in HA and hemophilia B.

CONCLUSION

Endogenous factor activity of >5% was identified as a threshold to significantly lower joint bleeding rate, while FVIII levels >15% and FIX levels >10% were sufficient to achieve the goal of 0 bleeds in this pediatric cohort.

Bleeding risk in hemophilia A and B carriers: comparison of factor levels determined using chronometric and chromogenic assays

BACKGROUND

Predicting the bleeding risk in hemophilia A and B carriers (HAC, HBC) is challenging.

OBJECTIVE

The objectives of this study were to describe the bleeding phenotype in HAC and HBC using the standardized Tosetto bleeding score (BS); to determine whether the BS correlates better with factor levels measured with a chromogenic assay than with factor levels measured with chronometric and thrombin generation assays; and to compare the results in HAC and HBC.

METHODS

This ambispective, noninterventional study included obligate and sporadic HAC and HBC followed at a hemophilia treatment center between 1995 and 2019.

RESULTS AND CONCLUSION

The median BS (3, range 0-21 vs. 3.5, range 0-15, P  = ns, respectively) and the abnormal BS rate (35.6% vs. 38.2%, P  = ns) were not significantly different in 104 HAC and 34 HBC (mean age: 38 years, 6-80 years). However, some differences were identified. The risk of factor deficiency was higher in HBC than HAC. Specifically, Factor VIII activity (FVIII):C/Factor IX activity (FIX):C level was low (<40 IU/dl) in 18.3% (chronometric assay) and 17.5% (chromogenic assay) of HAC and in 47% and 72.2% of HBC ( P  < 0.001). Moreover, the FIX:C level thresholds of 39.5 IU/dl (chronometric assay) and of 33.5 IU/dl (chromogenic assay) were associated with very good sensitivity (92% and 100%, respectively) and specificity (80% for both) for bleeding risk prediction in HBC. Conversely, no FVIII:C level threshold could be identified for HAC, probably due to FVIII:C level variations throughout life.

Emicizumab prophylaxis in infants with hemophilia A (HAVEN 7): primary analysis of a phase 3b open-label trial

ABSTRACT

Subcutaneous emicizumab enables prophylaxis for people with hemophilia A (HA) from birth, potentially reducing risk of bleeding and intracranial hemorrhage (ICH). HAVEN 7 (NCT04431726) is the first clinical trial of emicizumab dedicated to infants, designed to investigate the efficacy, safety, pharmacokinetics, and pharmacodynamics of emicizumab in those aged ≤12 months with severe HA without factor VIII (FVIII) inhibitors. Participants in this phase 3b trial received emicizumab 3 mg/kg maintenance dose every 2 weeks for 52 weeks and are continuing emicizumab during the 7-year long-term follow-up. Efficacy end points included annualized bleed rate (ABR): treated, all, treated spontaneous, and treated joint bleeds. Safety end points included adverse events (AEs), thromboembolic events (TEs), thrombotic microangiopathies (TMAs), and immunogenicity (anti-emicizumab antibodies [ADAs] and FVIII inhibitors). At primary analysis, 55 male participants had received emicizumab (median treatment duration: 100.3; range, 52-118 weeks). Median age at informed consent was 4.0 months (range, 9 days to 11 months 30 days). Model-based ABR for treated bleeds was 0.4 (95% confidence interval, 0.30-0.63), with 54.5% of participants (n = 30) having zero treated bleeds. No ICH occurred. All 42 treated bleeds in 25 participants (45.5%) were traumatic. Nine participants (16.4%) had ≥1 emicizumab-related AE (all grade 1 injection-site reactions). No AE led to treatment changes. No deaths, TEs, or TMAs occurred. No participant tested positive for ADAs. Two participants were confirmed positive for FVIII inhibitors. This primary analysis of HAVEN 7 indicates that emicizumab is efficacious and well tolerated in infants with severe HA without FVIII inhibitors.

The current challenges faced by people with hemophilia B

Hemophilia B (HB) is a rare, hereditary disease caused by a defect in the gene encoding factor IX (FIX) and leads to varying degrees of coagulation deficiency. The prevailing treatment for people with HB (PWHB) is FIX replacement product. The advent of recombinant coagulation products ushered in a new era of safety, efficacy, and improved availability compared with plasma-derived products. For people with severe HB, lifelong prophylaxis with a FIX replacement product is standard of care. Development of extended half-life FIX replacement products has allowed for advancements in the care of these PWHB. Nonetheless, lifelong need for periodic dosing and complex surveillance protocols pose substantive challenges in terms of access, adherence, and healthcare resource utilization. Further, some PWHB on prophylactic regimens continue to experience breakthrough bleeds and joint damage, and subpopulations of PWHB, including women, those with mild-to-moderate HB, and those with inhibitors to FIX, experience additional unique difficulties. This review summarizes the current challenges faced by PWHB, including the unique subpopulations; identifying the need for improved awareness, personalized care strategies, and new therapeutic options for severe HB, which may provide future solutions for some of the remaining unmet needs of PWHB.

Emicizumab use in females with moderate or mild hemophilia A without factor VIII inhibitors who warrant prophylaxis

Background

Hemophilia A (HA) is predominantly associated with males due to X-linked inheritance. Males and females with HA have shared unmet medical needs, highlighting the necessity for comprehensive care irrespective of sex.

Objectives

This analysis investigated the efficacy and safety of emicizumab prophylaxis in 3 females with HA.

Methods

HAVEN 6 (NCT04158648) is a phase III study of emicizumab in people with non-severe HA without factor (F)VIII inhibitors warranting prophylaxis per investigator assessment, and the study methodology has been reported previously. Female-specific endpoints included menstruation-related quality of life and menstruation heaviness.

Results

HAVEN 6 enrolled 3 females aged ≥18 years and within reproductive age (n = 2 mild HA; n = 1 moderate HA; n = 2 receiving prior FVIII prophylaxis; n = 1 receiving prior episodic FVIII). Participants presented with diverse bleeding phenotypes at baseline: 2 had no bleeds in the 24 weeks prior to enrollment, while 1 had an annualized bleed rate for all bleeds of 208.6. On-study annualized bleed rates for all bleeds were 0, 2.8, and 11.6, respectively. The 2 evaluable participants indicated improved menstruation-related quality of life vs baseline. Two participants experienced 3 grade 1/2 treatment-related adverse events; no new safety signals were identified. All 3 participants preferred emicizumab over their previous treatment and reported a better score for treatment burden and preoccupation domains of the Comprehensive Assessment Tool of Challenges in Hemophilia questionnaire.

Conclusion

Overall, results were consistent with those reported in the male population enrolled in the HAVEN 6 study, suggesting efficacy and a favorable safety profile for emicizumab in females with non-severe HA warranting prophylaxis.

Skewed X-inactivation is associated with retinal dystrophy in female carriers of RPGR mutations

Progressive degeneration of rod and cone photoreceptors frequently is caused by mutations in the X-chromosomal gene Retinitis Pigmentosa GTPase Regulator (RPGR). Males hemizygous for a RPGR mutation often are affected by Retinitis Pigmentosa (RP), whereas female mutation carriers only occasionally present with severe RP phenotypes. The underlying pathomechanism leading to RP in female carriers is not well understood. Here, we analyzed a three-generation family in which two of three female carriers of a nonsense RPGR mutation presented with RP. Among two cell lines derived from the same female family members, differences were detected in RPGR transcript expression, in localization of RPGR along cilia, as well as in primary cilium length. Significantly, these differences correlated with alterations in X-chromosomal inactivation patterns found in the patient-derived cell lines from females. In summary, our data suggest that skewed X-chromosomal inactivation is an important factor that determines the disease manifestation of RP among female carriers of pathogenic sequence alterations in the RPGR gene.

Closing the Diagnostic Gap in Adolescents and Young Adult Women With Bleeding Disorders: Missed Opportunities

Approximately 2% of the general population have an underlying inherited bleeding disorder, which, for adolescents and young adult women, has both physical risks and adverse psychosocial effects. Heavy menstrual bleeding can be the first sign of an underlying bleeding disorder such as von Willebrand disease and the X-linked bleeding disorders hemophilia A and B. Connective tissue disorders such as Ehlers-Danlos syndrome, in particular the hypermobile subtype, are relatively frequent in the general population and can also cause bleeding symptoms from impaired hemostasis due to defective collagen. For more than 20 years, the American College of Obstetricians and Gynecologists (ACOG) has recommended screening adolescents and young adult women for bleeding disorders when they present with heavy menstrual bleeding. Despite this directive, there is a significant gap from symptom onset to time of diagnosis in this patient population. We must work to effectively close this diagnostic gap by consistently obtaining thorough bleeding histories, performing the appropriate laboratory evaluations, working collaboratively with hematologists, and using tools and materials promoted by ACOG. Improved screening and earlier diagnosis of these individuals can have far-reaching effects that are not limited to heavy menstrual bleeding management and extend to peripartum considerations and prenatal counseling.

Four Decades of Carrier Detection and Prenatal Diagnosis in Hemophilia A: Historical Overview, State of the Art and Future Directions

Hemophilia A (HA), a rare recessive X-linked bleeding disorder, is caused by either deficiency or dysfunction of coagulation factor VIII (FVIII) resulting from deleterious mutations in the F8 gene encoding FVIII. Over the last 4 decades, the methods aimed at determining the HA carrier status in female relatives of HA patients have evolved from phenotypic studies based on coagulation tests providing merely probabilistic results, via genetic linkage studies based on polymorphic markers providing more accurate results, to next generation sequencing studies enabling highly precise identification of the causative F8 mutation. In parallel, the options for prenatal diagnosis of HA have progressed from examination of FVIII levels in fetal blood samples at weeks 20-22 of pregnancy to genetic analysis of fetal DNA extracted from chorionic villus tissue at weeks 11-14 of pregnancy. In some countries, in vitro fertilization (IVF) combined with preimplantation genetic diagnosis (PGD) has gradually become the procedure of choice for HA carriers who wish to prevent further transmission of HA without the need to undergo termination of pregnancies diagnosed with affected fetuses. In rare cases, genetic analysis of a HA carrier might be complicated by skewed X chromosome inactivation (XCI) of her non-hemophilic X chromosome, thus leading to the phenotypic manifestation of moderate to severe HA. Such skewed XCI may be associated with deleterious mutations in X-linked genes located on the non-hemophilic X chromosome, which should be considered in the process of genetic counseling and PGD planning for the symptomatic HA carrier. Therefore, whole exome sequencing, combined with X-chromosome targeted bioinformatic analysis, is highly recommended for symptomatic HA carriers diagnosed with skewed XCI in order to identify additional deleterious mutations potentially involved in XCI skewing. Identification of such mutations, which may profoundly impact the reproductive choices of HA carriers with skewed XCI, is extremely important.

Evaluation of clinical characteristics, health care resource utilization, and cost outcomes of hemophilia A carriers and noncarriers in the United States: A real-world comparative analysis

BACKGROUND: Hemophilia A is often viewed as a male disease; females are usually considered asymptomatic hemophilia A carriers. However, hemophilia A carriers may experience mild-to-severe bleeding events. OBJECTIVE: To compare clinical characteristics, health care resource utilization, and costs incurred by hemophilia A carriers compared with a non-hemophilia A carrier female control population in the United States. METHODS: This retrospective observational cohort study used data from IBM MarketScan Commercial Claims and Encounters and Multi-State Medicaid Databases from January 1, 2016, to September 30, 2019. Patients with a hemophilia A carrier diagnosis were matched to a non-hemophilia A carrier female control group in a 1:2 ratio based on sociodemographic characteristics, pregnancy status, and insurance type. Billed annualized bleed rates, health care resource utilization, and annualized costs were evaluated. Generalized linear models compared annualized total costs in the hemophilia A carrier and control groups. RESULTS: After matching, the hemophilia A carrier group included 121 (Commercial) and 55 (Medicaid) patients, matched 1:2 in the control group. Patients in the hemophilia A carrier group (compared with the control group) had numerically higher joint-related health issues (Commercial: 11.6% vs 7.9%; Medicaid: 7.3% vs 4.5%) and lower soft-tissue disorders (Commercial: 13.2% vs 17.4%; Medicaid: 12.7% vs 14.5%). Musculoskeletal pain was higher (33.1% vs 31.0%) and lower (21.8% vs 25.5%) in the Commercial and Medicaid databases, respectively. Billed annualized bleed rates were higher in the hemophilia A carrier group (Commercial: 0.49 vs 0.33; Medicaid: 0.50 vs 0.29). Significantly more patients in the hemophilia A carrier group had minor bleeds (Commercial: 34.7% vs 22.3% [P = 0.001]; Medicaid: 43.6% vs 20.0% [P < 0.001]) and spontaneous bleeds (Commercial: 35.5% vs 21.5%; Medicaid: 47.3% vs 23.6% [P < 0.001 for both]). Outpatient visits represented the majority of health care resource utilization and were higher in the hemophilia A carrier group for all-cause and bleed-related claims; although less frequent, emergency department and inpatient visits followed a similar trend. In the Commercial and Medicaid databases, hemophilia A carriers incurred approximately 2 times higher mean (SD) all-cause health care total costs than patients in the control group (Commercial: $15,345 [21,871] vs $8,358 [11,939] per patient per year [PPPY]; Medicaid: $9,022 [19,461] vs $4,533 [9,532] PPPY). CONCLUSIONS: Hemophilia A carriers experienced more complications and incurred higher costs (resulting from more outpatient, emergency department, and inpatient visits) compared with patients in the control group. These data suggest that hemophilia A carriers have a high disease and economic burden and may benefit from early diagnosis and management to prevent long-term complications. DISCLOSURES: Dr Xing, Dr Bullano, Dr Caicedo, and Mr Farahbakhshian are employees of Takeda Pharmaceuticals U.S.A., Inc., hold Takeda stocks, and have been granted restricted stock shares; Drs Xing and Caicedo received support from Takeda Pharmaceuticals U.S.A., Inc., for travel to THSNA 2022, where the data included in this manuscript were presented. Dr Batt received consulting fees from Complete HEOR Solutions (CHEORS) LLC for the protocol development, data analysis, and interpretation of this study; she also holds stocks from Merck and Sanofi. Ms Kuharic is an employee of the University of Illinois at Chicago and has been supported by a Takeda fellowship during the execution of the study. Ms Chakladar and Ms Markan were employees of CHEORS LLC at the time of the study. CHEORS has received funding from Takeda Pharmaceuticals U.S.A., Inc., for conducting the analysis of this study. This study was funded by Takeda Pharmaceuticals U.S.A., Inc. The sponsor was involved in the study design; collection, analysis, and interpretation of data; development and review of the manuscript; and decision to submit manuscript to publication.

Women and girls with haemophilia: A retrospective cohort study in China

INTRODUCTION

Women and girls with haemophilia (WGH) may have spontaneous/traumatic bleeding similar to that in males with haemophilia, and in addition excessive bleeding during menstruation and delivery.

AIM

To characterize WGH in China and provide guidance for better management.

METHODS

We retrospectively analysed the characteristics of WGH registered in the Haemophilia Treatment Center Collaborative Network of China (HTCCNC) Registry, including demographics, diagnosis and treatment, bleeding characteristics, obstetrical and gynaecological experiences, and surgical history.

RESULTS

A total of 61 females had confirmed haemophilia. Diagnosis and treatment were typically delayed, longer in mild haemophilia than in severe and moderate. The most frequently reported bleeding manifestations were haemarthrosis in severe and moderate patients, and cutaneous bleeding in mild patients. Among 45 postmenarcheal WGH, 21 (46.7%) had history of heavy menstrual bleeding, but only three received treatments. Prenatal diagnosis and management of perinatal haemorrhage were inadequate. Of 34 deliveries in 30 women, nine deliveries were complicated by postpartum haemorrhage, and 22 offspring carried mutations causing haemophilia. Forty-four surgical procedures were performed in 29 patients. Those procedures receiving preoperative coagulation factors coverage were significantly less likely to have excessive bleeding than those who did not (P = .003).

CONCLUSION

This is the first and largest study describing WGH in China. There are currently deficiencies in the identification, diagnosis, and management of these patients. Improving health insurance policies, establishing haemophilia centres, and multidisciplinary teams for bleeding and perinatal or perioperative management will help reduce morbidity and mortality.

Prophylaxis use of clotting factor replacement products in people with non-severe haemophilia: A review of the literature

INTRODUCTION

People with non-severe haemophilia appear to be under-treated in many countries, and this may lead to joint damage and worsen quality of life.

AIM

To review literature for clotting factor replacement prophylaxis in people with non-severe haemophilia A and B (HA/HB) in relation to long-term outcomes to support clinical decision-making.

METHODS

A targeted literature search was performed to identify studies published between 2000 and 2021 that included prophylaxis in people with non-severe HA/HB and long-term outcomes, including annualized bleeding rates, joint health and quality of life.

RESULTS

Although eligible articles included 2737 and 2272 people with mild or moderate HA, respectively, only 22% (n = 609) and 29% (n = 668) reported treatment regimens. A total of 549 people with moderate HA were treated with factor replacement prophylaxis and were from high-income countries. On the contrary, nearly all people with mild HA received desmopressin (n = 599). Details of treatment regimens for women with haemophilia and people with HB were sparse. Three studies provided long-term outcomes for people with moderate haemophilia who received prophylaxis with factor concentrate, supporting early prophylaxis in people with a frequent bleeding phenotype regardless of their endogenous clotting factor level to preserve joint health.

CONCLUSION

There remain large knowledge gaps when considering how to provide optimal treatment for people with non-severe haemophilia. Nonetheless, there is a strong rationale that prophylaxis should be considered early in life according to similar strategies as for severe haemophilia for those with a frequent severe bleeding phenotype.

Determining the incidence of postpartum haemorrhage among Ontario women with and without inherited bleeding disorders: A population-based cohort study

INTRODUCTION

At a population level, there is a poor understanding of the incidence and pre-disposing risk factors of postpartum haemorrhage (PPH) among women with inherited bleeding disorders (IBD).

AIM

To determine the incidence of PPH, and identify maternal factors associated with risk of PPH among women with IBD.

METHODS

We conducted a retrospective cohort study using data housed within ICES (formerly known as the Institute for Clinical Evaluative Sciences). The cohort included women with an in-hospital, live or stillborn delivery, between January 2014 and December 2019. The primary outcome was PPH (identified by ICD-10 code O72). PPH incidence and risk factors were compared between women with and without IBD. Temporal trends were assessed using the Cochrane-Armitage test. Between group differences were assessed using standardised differences (std. difference).

RESULTS

Total 601,773 women were included; 2002 (.33%) had an IBD diagnosis. PPH incidence was 1.5 times higher (7.3 vs. 4.9 cases/100 deliveries, std. difference .1) among women with IBD compared to women without. Women with IBD were slightly older (31.7 vs. 30.7 years), had higher rates of hypertension, previous PPH, and induction of labour. Women with IBD were more frequently diagnosed with anaemia (4.8% vs. 1.8%; std difference .17) and had lower haemoglobin levels at admission for delivery compared to women without IBD.

CONCLUSIONS

This study contributes to the literature regarding obstetric bleeding among women with IBD, showing that anaemia at delivery may be an important risk factor for PPH. Given their predisposition to anaemia, clarifying this relationship will optimise management and outcomes.

Challenges and knowledge gaps facing hemophilia carriers today: Perspectives from patients and health care providers

Background

Hemophilia carriers experience abnormal bleeding symptoms; however, a lack of awareness about this topic coupled with additional knowledge gaps and barriers leads to suboptimal care for this population.

Objective

The primary objective was to describe the current knowledge gaps and challenges from the perspective of both hemophilia carriers and their health care providers.

Methods

We carried out a mixed methods descriptive study with two population groups between September and December 2020. The hemophilia carrier perspective was obtained through both focus groups and questionnaires, whereas the health care providers perspective obtained via questionnaire sent to the Association of Hemophilia Care Directors of Canada and the Canadian Association of Nurses in Hemophilia Care. Focus groups were analyzed using descriptive thematic analysis and quantitative survey data was also analyzed.

Results

Eleven hemophilia carriers participated along with 19 health care providers (11 physicians, eight nurses). Hemophilia carrier focus group discussions identified four areas representing major challenges or knowledge gaps: (1) negative psychosocial impacts; (2) difficulty determining symptom significance; (3) need for self-advocacy; (4) testing concerns. Survey results from both groups were aligned with the most important topics for ongoing education identified as information on abnormal bleeding symptoms, where to seek treatment, and considerations for heavy menstrual bleeding/menstruation. The majority of both study groups believe obligate or potential carriers should have factor levels checked regardless of age if symptoms of abnormal bleeding occur or before an invasive procedure. However, hemophilia carriers were significantly more in favor of genetic testing under the age of consent than health care providers in all scenarios evaluated.

Health issues in women and girls affected by haemophilia with a focus on nomenclature, heavy menstrual bleeding, and musculoskeletal issues

Introduction

Women and girls affected by haemophilia, including haemophilia carriers (WGH) are at risk of bleeding symptoms that may go unrecognized, including heavy menstrual bleeding (HMB) and musculoskeletal bleeding. Terminology continues to evolve.

Aim

To describe the current recommendations for nomenclature surrounding WGH, and the current understanding of HMB, iron deficiency, and musculoskeletal complaints in these patients.

Methods

Literature was reviewed and summarized.

Results

With regards to nomenclature, women with factor levels less than 50% should be classified as having haemophilia, while carriers with normal levels should be characterized accordingly to symptomatology. HMB and resultant iron deficiency are common among WGH, have a multitude of downstream effects, and maybe overlooked due to stigma around menstruation. Musculoskeletal bleeding and resultant joint changes are increasingly recognized in this population but do not necessarily correlate with factor levels.

Conclusion

Although progress has been made in the care of WGH, much work remains to further improve their care.

The Clinical Genetics of Hemophilia B (Factor IX Deficiency)

Hemophilia B (HB) is a bleeding disorder caused by deficiency of or defect in blood coagulation factor IX (FIX) inherited in an X-linked manner. It results from one of over 1000 known pathogenic variants in the FIX gene, F9; missense and frameshift changes predominate. Although primarily males are affected with HB, heterozygous females may have excessive bleeding due to random or non-random X chromosome inactivation; in addition, homozygous, compound heterozygous, and hemizygous females have been reported. Somatic and germinal mosaicism for F9 variants has been observed. Development of antibodies to FIX treatment products (inhibitors) is rare and related to the type of causative variant present. Treatment is with products produced by recombinant DNA technology, and gene therapy is in clinical trials. Genetic counseling with up-to-date information is warranted for heterozygotes, potential heterozygotes, and men and women affected with HB.

Women and girls with haemophilia receiving care at specialized haemophilia treatment centres in the United States

INTRODUCTION

Females may have haemophilia with the same factor VIII (FVIII) or factor IX (FIX) levels as affected males. Characterization of females with haemophilia would be useful for health care planning to meet their unique needs. Federally-funded haemophilia treatment centres (HTCs) in the United States contribute data on all individuals with bleeding disorders receiving care to the Population Profile (HTC PP) component of the Community Counts Public Health Surveillance of Bleeding Disorders project.

AIMS

To estimate the number of females with haemophilia receiving care at HTCs in the United States and compare their characteristics with those of males with haemophilia.

METHODS

HTC PP data collected on people receiving care at an HTC from January 2012 through September 2020 with haemophilia A and B were evaluated by sex for demographic and clinical characteristics.

RESULTS

A factor level < 40% was reported for 23,196 males (97.8%) and 1667 females (47.6%) attending HTCs; 51 (.48%) severe, 79 (1.4%) moderate, and 1537 (17.9%) mild haemophilia patients were female. Females were older, more often White, and less often non-Hispanic than males. Females were less likely to have history of HIV or HCV infection, even among those with severe disease, but twice as likely to have infection status unknown. Females with mild haemophilia were more often uninsured than males.

CONCLUSIONS

Females with severe or moderate haemophilia are uncommon, even in specialized care centres; however, almost one in five patients with mild haemophilia was female, indicating needs for specialized care based on factor level and history for affected females.

Molecular Mechanisms of Skewed X-Chromosome Inactivation in Female Hemophilia Patients-Lessons from Wide Genome Analyses

Introduction: Hemophilia A (HA) is an X-linked bleeding disorder caused by factor VIII (FVIII) deficiency or dysfunction due to F8 gene mutations. HA carriers are usually asymptomatic because their FVIII levels correspond to approximately half of the concentration found in healthy individuals. However, in rare cases, a carrier may exhibit symptoms of moderate to severe HA primarily due to skewed inactivation of her non-hemophilic X chromosome. Aim: The aim of the study was to investigate X-chromosome inactivation (XCI) patterns in HA carriers, with special emphasis on three karyotypically normal HA carriers presenting with moderate to severe HA phenotype due to skewed XCI, in an attempt to elucidate the molecular mechanism underlying skewed XCI in these symptomatic HA carriers. The study was based on the hypothesis that the presence of a pathogenic mutation on the non-hemophilic X chromosome is the cause of extreme inactivation of that X chromosome. Methods: XCI patterns were studied by PCR analysis of the CAG repeat region in the HUMARA gene. HA carriers that demonstrated skewed XCI were further studied by whole-exome sequencing (WES) followed by X chromosome-targeted bioinformatic analysis. Results: All three HA carriers presenting with the moderate to severe HA phenotype due to skewed XCI were found to carry pathogenic mutations on their non-hemophilic X chromosomes. Patient 1 was diagnosed with a frameshift mutation in the PGK1 gene that was associated with familial XCI skewing in three generations. Patient 2 was diagnosed with a missense mutation in the SYTL4 gene that was associated with familial XCI skewing in two generations. Patient 3 was diagnosed with a nonsense mutation in the NKAP gene that was associated with familial XCI skewing in two generations. Conclusion: Our results indicate that the main reason for skewed XCI in our female HA patients was negative selection against cells with a disadvantage caused by an additional deleterious mutation on the silenced X chromosome, thus complicating the phenotype of a monogenic X-linked disease. Based on our study, we are currently offering the X inactivation test to symptomatic hemophilia carriers and plan to expand this approach to symptomatic carriers of other X-linked diseases, which can be further used in pregnancy planning.

Regulation and importance of factor VIII levels in hemophilia A carriers

PURPOSE OF REVIEW

To summarize the recent literature related to female hemophilia A carriers with respect to prevalence in the population, the impact of baseline factor VIII levels and other influences on bleeding phenotype, and clinical management needs.

RECENT FINDINGS

Many female hemophilia A carriers are at risk for abnormal bleeding, yet they are underrecognized by healthcare providers and their bleeding symptoms are underreported. Low FVIII levels are consistently associated with clinically significant bleeding and correlate well with skewed X chromosome inactivation (XCI). Most interestingly, bleeding tendency is also observed in some hemophilia A carriers with normal factor VIII levels and requires further investigation. Well controlled studies investigating peripartum and periprocedural FVIII levels and adequate hemostatic treatment are necessary to inform management guidelines.

SUMMARY

Prevalence and bleeding tendency of hemophilia A carriers remain underreported, despite a significant proportion having low FVIII levels. Skewed XCI may explain low FVIII but does not explain the bleeding risk encountered in a larger proportion of hemophilia A carriers with random XCI and borderline/normal FVIII.

Gene Therapy for Inherited Bleeding Disorders

Decades of preclinical and clinical studies developing gene therapy for hemophilia are poised to bear fruit with current promising pivotal studies likely to lead to regulatory approval. However, this recent success should not obscure the multiple challenges that were overcome to reach this destination. Gene therapy for hemophilia A and B benefited from advancements in the general gene therapy field, such as the development of adeno-associated viral vectors, as well as disease-specific breakthroughs, like the identification of B-domain deleted factor VIII and hyperactive factor IX Padua. The gene therapy field has also benefited from hemophilia B clinical studies, which revealed for the first time critical safety concerns related to immune responses to the vector capsid not anticipated in preclinical models. Preclinical studies have also investigated gene transfer approaches for other rare inherited bleeding disorders, including factor VII deficiency, von Willebrand disease, and Glanzmann thrombasthenia. Here we review the successful gene therapy journey for hemophilia and pose some unanswered questions. We then discuss the current state of gene therapy for these other rare inherited bleeding disorders and how the lessons of hemophilia gene therapy may guide clinical development.

Genetic causes of haemophilia in women and girls

Women and girls reported as "haemophilic females" may have complex genetic causes for their haemophilia phenotype. In addition, women and girls may have excessive bleeding requiring treatment simply because they are heterozygous for haemophilia alleles. While severe and moderate haemophilia are rare in females, 16% of patients with mild haemophilia A and almost one-quarter of those with mild haemophilia B seen in U.S. haemophilia treatment centres are women and girls. A phenotypic female with a low level of factor VIII or factor IX may be classified into one of the following categories of causality: homozygosity (two identical haemophilia alleles), compound heterozygosity (two different haemophilia alleles), hemizygosity (one haemophilia allele and no normal allele), heterozygosity (one haemophilia allele and one normal allele), genetic causes other than haemophilia and non-genetic causes. Studies required for classification may include coagulation parameters, F8 or F9 sequencing, F8 inversion testing, multiplex ligation-dependent probe amplification, karyotyping and X chromosome inactivation studies performed on the patient and parents. Women and girls who are homozygous, compound heterozygous or hemizygous clearly have haemophilia, as they do not have a normal allele. Heterozygous women and girls with factor levels below the haemostatic range also meet the definitions used for haemophilia treatment.

Identified unmet needs and proposed solutions in mild-to-moderate haemophilia: A summary of opinions from a roundtable of haemophilia experts

INTRODUCTION

The experiences of patients with mild-to-moderate haemophilia differ from those of patients with severe haemophilia or those without a bleeding disorder and include a challenging diagnosis and variability in bleeding symptoms and treatment needs. In addition, there is a significant lack of data on mild-to-moderate haemophilia, and many unmet needs remain to be identified and addressed in this group of patients.

METHODS

Challenges for these patients, including women with haemophilia, were identified during a roundtable meeting attended by a group of US-based experts including healthcare professionals (e.g., physicians, nurses, and physical therapists) and patients who live with a bleeding disorder.

RESULTS

Identified unmet needs included a lack of proper education on the management of their disorder and prompt treatment of bleeds, absenteeism from school and work, and challenges with personal relationships. Initiatives to assist with alleviating these unmet needs were proposed and include suggestions for healthcare professionals, haemophilia treatment centres (HTCs) and national and local organizations within the bleeding disorders community. These included HTC and community engagement programmes for patients with mild-to-moderate haemophilia, revised transition guidelines for these patients as they approach adulthood and revised diagnostic classification of mild and moderate haemophilia. Challenges unique to women with haemophilia and ways to address these issues were also discussed.

CONCLUSION

This paper summarizes the challenges, initiatives and suggestions that were identified by the haemophilia experts during the roundtable meeting.

Maternal Hematologic Conditions and Fetal/Neonatal Outcomes of Pregnancy

Hematologic conditions in reproductive-age women can complicate pregnancy and the neonatal period. Affected pregnancies have a higher risk of severe morbidity and mortality. Coagulation factor changes that occur in the normal state of pregnancy can delay detection and recognition of a bleeding disorder in cases without an apparent bleeding history, thus hindering the appropriate management during gestation and the neonatal period. In addition, unique maternal immunologic changes occur during pregnancy, which are meant to protect the fetus who shares paternal antigens. Rarely, derangement of the maternal immune system may result in alloimmunization against fetal platelet antigens, leading to the development of fetal and/or neonatal thrombocytopenia. Bleeding and platelet disorders pose significant risk of intracranial hemorrhage for the fetus and newborn that is associated with significant morbidity and mortality. We discuss contemporary diagnosis and management of rare bleeding and platelet disorders in pregnancy and their effect on the neonatal period.

Impact of haemophilia on patients with mild-to-moderate disease: Results from the P-FiQ and B-HERO-S studies

INTRODUCTION

Epidemiologic studies suggest that joint bleeding occurs in patients with mild-to-moderate haemophilia, including women and girls. However, most previous studies on the impacts of haemophilia focus on men with severe disease.

AIM

To identify unmet needs in men and women with mild-to-moderate haemophilia.

METHODS

The Pain, Functional Impairment, and Quality of Life (P-FiQ) study assessed the impact of pain on functional impairment and health-related quality of life in men with haemophilia A or B of any severity. The Bridging Hemophilia B Experiences, Results and Opportunities Into Solutions (B-HERO-S) study evaluated the psychosocial needs of adults and children with haemophilia B of any severity, including women and girls. Both studies employed patient-reported outcome measures.

RESULTS

In the P-FiQ study, 16% (62/381) of participants had mild and 13% (50/381) had moderate haemophilia. In the B-HERO-S study, 29% (86/299) of adult participants were female, 25% (74/299) had mild haemophilia, and 63% (189/299) had moderate haemophilia. In addition, 63% (46/74) of patients with mild and 86% (162/189) of patients with moderate haemophilia routinely infused factor products to prevent bleeding. Patients reported difficulty gaining access to factor products (54%; 142/263) and a haemophilia treatment centre (17%; 44/263). During the P-FiQ study, 78% (48/62) of patients with mild and 87% (44/50) with moderate haemophilia described problems with pain on the Brief Pain Inventory. Patients also reported issues with anxiety, depression and relationships.

CONCLUSIONS

Mild-to-moderate haemophilia has physical and psychosocial impacts on patients. We offer some solutions to help alleviate these impacts and resolve unmet needs.

Current challenges for men and women with mild-to-moderate haemophilia

Current treatments in the field of haemophilia are changing the phenotype of many patients with severe haemophilia to that of mild haemophilia. Despite this improvement, those with mild-to-moderate haemophilia A and haemophilia B continue to experience unmet needs. Whereas some patients with mild-to-moderate haemophilia experience similar complications to those of patients with severe haemophilia, they possess several unique attributes. These include a challenging diagnosis and variability in bleeding symptoms and treatment needs. In addition, haemophilia is an under-recognized condition in women even though many women with mild-to-moderate haemophilia experience the same symptoms and complications as men with haemophilia. These women also have their own unique challenges with this disease. This supplement highlights many of the unmet needs in men and women with mild-to-moderate haemophilia. The conclusions of each of these papers reinforce the need for additional research and resources for this patient population.

Sexism in the management of bleeding disorders

Sexism has been an issue in bleeding disorders for centuries. Women with bleeding disorders have been underrecognized and underdiagnosed. Those who are diagnosed often experience delays in diagnosis and feel that their symptoms are dismissed or minimized. Several factors contribute to this sexism. Historically, the clinical and research focus within the bleeding disorder community has been on men and hemophilia. Von Willebrand disease, a disease that has long been recognized as affecting women, is much more common than hemophilia, yet has significantly fewer resources devoted to it. The lack of knowledge and comfort that patients and health care providers have regarding menstruation compounds the issue, as heavy menstrual bleeding is one of the most common symptoms seen in women with bleeding disorders. Stemming from the universal stigmatization of periods, this lack of comfort and knowledge results in fewer women seeking care, fewer health care providers addressing the issue, and fewer women getting the care they deserve. Progress has been made, with many organizations dedicating resources to improving the care of these women. The road is long, and much more work is needed to ensure that women with bleeding disorders receive the care they deserve.

Women and girls with haemophilia and bleeding tendencies: Outcomes related to menstruation, pregnancy, surgery and other bleeding episodes from a retrospective chart review

Introduction

Women or girls with haemophilia (WGH) represent a group of female symptomatic carriers who experience bleeding events more frequently than non‐carriers. Bleeding events include spontaneous/traumatic bleeds and prolonged bleeding related to surgery, menstruation and pregnancy. Challenges for the treatment of WGH include lack of screening, diagnosis and treatment guidelines.

Aim

Evaluate clinical characteristics, haemostasis management and clinical outcomes regarding menstruation, childbirth, dental procedures, surgeries and other bleeding events in WGH.

Methods

A retrospective, non‐interventional review of medical records from WGH among three haemophilia treatment centres (HTCs) was conducted in the United States (2012–2018). Patients with ≥2 visits to the HTC and who had undergone intervention for haemostasis management with the outcome documented were included. Descriptive statistics were used.

Results

Of 47 women and girls included in the chart review (37 with factor VIII deficiency, 10 with factor IX deficiency), median age at diagnosis was 22.6 years. Approximately 79% (n = 37) were diagnosed with mild haemophilia. Events of interest were primarily managed by factor concentrates or antifibrinolytics. Most treatment approaches were successful across clinical scenarios, except for heavy menstrual bleeding being insufficiently controlled in 8 (57%) of the 14 patients who experienced it.

Conclusions

Bleeding events in WGH, such as excessive and prolonged bleeding during menstruation, demonstrate a unique burden and require specific medical intervention. These results highlight the importance of assessing the need for haemostasis management in WGH and may contribute to future prospective study designs.

General concepts on hemophilia A and on women carrying the disease

Hemophilia A affects one in every 5000 live male births. As the disorder follows a hereditary X-linked recessive pattern, women who inherit the mutation become carriers of the disease. The exact prevalence of carriers of hemophilia A or B is unknown. A search of the literature identified only one study that provides an approximation. According to its authors, for every 100 male with hemophilia there are 277 potential carriers. We will review through this supplement carrier condition from reproductive to care giver and individual point of view.

Skewed Inactivation of X Chromosome: A Cause of Hemophilia Manifestation in Carrier Females

Hemophilia is an X-linked recessive hereditary disorder that classically affects males due to the presence of only one X chromosome in males. Females are usually carriers due to the presence of counterpart X chromosome, but many times manifestations of hemophilia are seen in heterozygous carrier females. This is a result of skewed lionization, in which more normal X chromosomes are converted to bar body, and more abnormal chromosomes remain active in body cells, causing the dominant manifestation of the disease. The severity of manifestations is directly proportional to the level of the clotting factor in the blood. The disease can be severe enough to cause life-threatening bleeding, especially during delivery. Physicians usually reluctant to assume hemophilia in the differential diagnosis of the bleeding disorders in women but manifesting carrier females with hemophilia are not uncommon. Our review of the literature will give an opportunity to understand this issue more precisely as well as will discuss the disease manifestations and its updated management.

X Chromosome inactivation: a modifier of factor VIII and IX plasma levels and bleeding phenotype in Haemophilia carriers

Haemophilia A and B are X-linked hemorrhagic disorders caused by gene variants in the F8 and F9 genes. Due to recessive inheritance, males are affected, while female carriers are usually asymptomatic with a wide range of factor VIII (FVIII) or IX (FIX) levels. Bleeding tendency in female carriers is extremely variable and may be associated with low clotting factor levels. This could be explained by F8 or F9 genetic variations, numerical or structural X chromosomal anomalies, or epigenetic variations such as irregular X chromosome inactivation (XCI). The aim of the study was to determine whether low FVIII or FIX coagulant activity in haemophilia carriers could be related to XCI and bleeding symptoms. HUMARA assay was performed on 73 symptomatic carriers with low clotting activity ≤50 IU/dL. Bleeding Assessment Tool (BAT) from the International Society on Thrombosis and Haemostasis (ISTH) was used to describe symptoms in the cohort of carriers. In 97% of haemophilia carriers, a specific gene variant in heterozygous state was found, which alone could not justify their low FVIII or FIX levels (≤50 IU/dL). A statistical association between XCI pattern and FVIII and FIX levels was observed. Moreover, female carriers with low coagulant activity (≤20 IU/dL) and high degree of XCI ( ≥ 80:20) had a higher ISTH-BAT score than the carriers with the opposite conditions (>20 IU/dL and <80:20). In our cohort of haemophilia carriers, XCI was significantly skewed, which may contribute to the low expression of clotting factor levels and bleeding symptoms.

Women and girls with haemophilia: Lessons learned

Severe and moderate factor VIII (FVIII) or IX (FIX) deficiencies in female carriers of haemophilia are rarely observed, but mild deficiency is quite frequent, although insufficiently recognized and registered. The confusion between the genetic diagnosis of the carriership, mainly assessed at adult age and the diagnosis of the bleeding disorder for those who have low factor levels often prevents early diagnosis of a potential bleeding risk. The factor levels in obligate or potential carriers of haemophilia can be assessed during childhood, possibly apart from genetic assays. The absence of early recognition of the bleeding disorder precludes the anticipation of menarche and the prevention of potential heavy menstrual bleeding to heavy menstrual bleeding. Standardized bleeding assessment tools (BAT) have demonstrated that women and girls with haemophilia (WGWH) have increased bleeding scores as compared to the general female population, however weakly correlating with factor levels. More recent evidence has highlighted that hemarthroses affect 4% to 19% of carriers and that some of them could experience sub-clinical joint bleeding. Desmopressin for women with FVIII deficiency and abnormal ISTH-BAT scores had a significantly lower FVIII response to DDAVP compared to those with normal bleeding scores, which could at least partially explain more postsurgical bleeding. Management of delivery of haemophilia carriers requires attention to the risks of maternal bleeding, the risks of foetal bleeding, preconception and prenatal care, strategies to reduce maternal bleeding, choice of mode of delivery to reduce foetal/neonatal bleeding, and postpartum care. Either prior to pregnancy, or during early pregnancy, a plan should be developed that addresses the needs of both the mother and her unborn baby. If the unborn baby is a male proven to be or potentially affected by moderate or severe form of haemophilia, there is a risk of severe foetal bleeding, so a planned caesarean delivery may be preferred. If the unborn baby is a carrier, or potentially affected carrier, there is still the risk of non-severe bleeding so invasive foetal procedures and operative vaginal delivery (forceps or vacuum) should be avoided. Further studies based on large cohorts will help the community to favour earlier diagnosis, increase knowledge on WGWH and promote better care.

Deep intronic F8 c.5999-27A>G variant causes exon 19 skipping and leads to moderate hemophilia A

: Hemophilia A, an X-linked recessive bleeding disorder, is caused by mutations of F8 gene. In about 2% hemophilia A patients, no exonic mutation of F8 gene was found. We aimed to identify deep intronic mutations of F8 gene. We reanalyzed the next-generation sequencing data of six hemophilia A patients with negative F8 variant in either coding region or splice site. Deep intronic F8 c.5999-27A>G variant (NM_000132.3) was found in two unrelated moderate hemophilia A patients from different region, and one patient's mother was mild hemophilia A patient. Splice site prediction algorithms showed no impact of this variant on F8 mRNA splicing of exon 19, including Human Splicing Finder 3.1, NNSPLICE 0.9, NetGene2, and Transcript-inferred Pathogenicity score. Exonic splicing enhancer was predicted by ESEfinder, and no difference was found between the wild type and mutant sequence. The branch point predicted by SVM-BPfinder suggested that F8 c.5999-27A>G variant may disrupt the branch point in intron 18 and affect the acceptor site splicing of F8 exon 19. Sanger sequencing of F8 cDNA from peripheral blood mononuclear cells confirmed that F8 c.5999-27A>G variant caused F8 exon 19 skipping in proband and his mother. Skewed X chromosome inactivation was found in another X chromosome of this mother, combined with F8 c.5999-27A>G variant in trans. In conclusion, our study suggests that deep intronic F8 c.5999-27A>G variant may be responsible for F8 exon 19 skipping and lead to moderate hemophilia A. Systematic reanalysis of next-generation sequencing data could promote the diagnostic yields.

Six molecular patterns leading to hemophilia A phenotype in 18 females from Poland

INTRODUCTION

Female hemophilia is an intriguing rare disorder and few larger reports on its genetic etiology are available. While historically the diagnosis was satisfactorily reached by factor VIII activity assays, the clinical and potentially therapeutic heterogeneity of female hemophilia calls for comprehensive molecular diagnosis in each case. Currently, the genetic investigations are not a part of routine, state-funded, diagnostics in Poland, and thus molecular epidemiological data are missing.

AIM

We set out to perform a comprehensive genetic analysis of Polish females with hemophilia A.

PATIENTS/METHODS

Eighteen females with hemophilia A (including 2 with severe and 5 with moderate hemophilia phenotype) consented for genetic diagnostics. To establish F8 mutations, we used next-generation sequencing of a panel of genes associated with hematological disorders, standard assays for recurrent intragenic F8 inversions and MLPA when deletions were suspected. When appropriate we also used karyotyping, genomic microarrays and X chromosome inactivation assays.

RESULTS

While abnormally skewed X-chromosome inactivation combined with a F8 variant on the active allele was, as expected, the most common genetic etiology, a number of other genetic scenarios were unraveled. This included: misdiagnosis (molecular diagnosis of vWd), Turner syndrome, compound heterozygosity and androgen insensitivity syndrome (a phenotypical 46,XY female with a novel androgen receptor gene mutation). We report 3 novel F8 mutations.

CONCLUSION

Every case of female hemophilia warrants full genomic diagnostics, as this may change the diagnosis or reveal broader morbidity than a coagulation disorder (Turner syndrome, androgen insensitivity, or cardiovascular morbidity that we described previously in a SHAM syndrome carrier).

Occurrence rates of haemophilia among males in the United States based on surveillance conducted in specialized haemophilia treatment centres

INTRODUCTION

Estimates of the size and characteristics of the US haemophilia population are needed for healthcare planning and resource needs assessment. A network of comprehensive haemophilia treatment centres (HTCs) located throughout the United States receives federal support for diagnosis and management of haemophilia and other rare bleeding disorders.

AIM

Estimate the incidence and prevalence of haemophilia among US males using the HTC network.

METHODS

During the period 2012-2018, de-identified surveillance data were collected on all males who visited an HTC that included year of birth, gender, race, Hispanic ethnicity, residence zip code, haemophilia type and severity. Data from all patients were used to calculate period prevalence by haemophilia type, severity and state of residence. Data from a subset of patients born 1995-2014 were used to estimate incidence rates over the 20-year period.

RESULTS

During the period, 21 748 males with haemophilia visited the HTCs resulting in an age-adjusted prevalence of 15.7 cases per 100 000 males (12 for haemophilia A and 3.7 for haemophilia B). Prevalence was higher among whites (15.1) than blacks (12.4) or Hispanics of either race (12.4). State-specific prevalence varied from 1.6 to 23.3 cases per 100 000. Based on 9587 males born during the index period, the average haemophilia incidence was 1 case per 4334 live male births.

CONCLUSION

Based on these data, we estimate that there are between 29 761 and 32 985 males with haemophilia living in the United States today, the majority of whom receive comprehensive care in specialized clinical centres.

Reduced bone formation in males and increased bone resorption in females drive bone loss in hemophilia A mice

Hemophilia A (HA), a rare X-linked recessive genetic disorder caused by insufficient blood clotting factor VIII, leaves affected individuals susceptible to spontaneous and traumatic hemorrhage. Although males generally exhibit severe symptoms, due to variable X inactivation, females can also be severely impacted. Osteoporosis is a disease of the skeleton predisposing patients to fragility fracture, a cause of significant morbidity and mortality and a common comorbidity in HA. Because the causes of osteoporosis in HA are unclear and in humans confounded by other traditional risk factors for bone loss, in this study, we phenotyped the skeletons of F8 total knockout (F8 ^TKO) mice, an animal model of severe HA. We found that trabecular bone accretion in the axial and appendicular skeletons of male F8 ^TKO mice lagged significantly between 2 and 6 months of age, with more modest cortical bone decline. By contrast, in female mice, diminished bone accretion was mostly limited to the cortical compartment. Interestingly, bone loss was associated with a decline in bone formation in male mice but increased bone resorption in female mice, a possible result of sex steroid insufficiency. In conclusion, our studies reveal a sexual dimorphism in the mechanism driving bone loss in male and female F8 ^TKO mice, preventing attainment of peak bone mass and strength. If validated in humans, therapies aimed at promoting bone formation in males but suppressing bone resorption in females may be indicated to facilitate attainment of peak mass in children with HA to reduce the risk for fracture later in life.

Hemophilia A in Females: Considerations for Clinical Management

Approximately 50% of female carriers of hemophilia A have factor VIII (FVIII) levels below 0.5 IU/dL and may be categorized as having mild hemophilia. Females with hemophilia may go undiagnosed for years because the most common symptoms - menorrhagia and bleeding after childbirth - also occur in females without hemophilia. Females with hemophilia can exhibit increased bleeding tendencies despite current guidelines of expected, adequate FVIII levels. The cases described illustrate the clinical variability and presentation of hemophilia in females and highlight the importance of a timely diagnosis, effective management, and monitoring. Prophylactic factor replacement therapy is recommended in females with hemophilia, particularly those with joint disease or gynecologic complications. Affected individuals should receive infusion training and education on treatment options, physical activities, the importance of treatment adherence, and recognizing bleeding symptoms warranting treatment. Further study is needed to increase awareness of hemophilia in females and reassess current guidelines for their management and monitoring.

Mechanistic Insights into Factor VIII Immune Tolerance Induction via Prenatal Cell Therapy in Hemophilia A

Purpose of Review

Prenatal stem cell and gene therapy approaches are amongst the few therapies that can promise the birth of a healthy infant with specific known genetic diseases. This review describes fetal immune cell signaling and its potential influence on donor cell engraftment, and summarizes mechanisms of central T cell tolerance to peripherally-acquired antigen in the context of prenatal therapies for Hemophilia A.

Recent Findings

During early gestation, different subsets of antigen presenting cells take up peripherally-acquired, non-inherited antigens and induce the deletion of antigen-reactive T-cell precursors in the thymus, demonstrating the potential for using prenatal cell and gene therapies to induce central tolerance to FVIII in the context of prenatal diagnosis/therapy of Hemophilia A.

Summary

Prenatal cell and gene therapies are promising approaches to treat several genetic disorders including Hemophilia A and B. Understanding the mechanisms of how FVIII-specific tolerance is achieved during ontogeny could help develop novel therapies for HA and better approaches to overcome FVIII inhibitors.

X-Chromosome Inactivation Is a Biomarker of Clinical Severity in Female Carriers of RPGR-Associated X-Linked Retinitis Pigmentosa

PURPOSE

X-linked retinitis pigmentosa can manifest in female carriers with widely variable severity, whereas others remain unaffected. The contribution of X-chromosome inactivation (XCI) to phenotypic variation has been postulated but not demonstrated. Furthermore, the impact of genotype and genetic modifiers has been demonstrated in affected males but has not been well established in female carriers. The purpose of this study was to describe the scope of clinical phenotype in female carriers with mutations in RPGR and quantify the contribution of genotype, genetic modifiers, and XCI to phenotypic severity.

DESIGN

Cohort study.

PARTICIPANTS

Seventy-seven female carriers with RPGR mutations from 41 pedigrees.

METHODS

Coding single nucleotide polymorphisms were sequenced in candidate genetic modifier genes encoding known RPGR-interacting proteins. X-chromosome inactivation ratios were determined in genomic DNA isolated from blood (n = 42) and saliva (n = 20) using methylation status of X-linked polymorphic repeats. These genetic data were compared with disease severity based on quantitative clinical parameters.

MAIN OUTCOME MEASURES

Visual acuity, Humphrey visual field (HVF) results, full-field electroretinography results, and dark adaptation.

RESULTS

Most individuals at all ages were mildly affected or unaffected, whereas those who progressed to moderate or severe vision loss were older than 30 years. RPGR genotype was not associated with clinical severity. The D1264N variant in RPGRIP1L was associated with more severe disease. Skewed XCI toward inactivation of the normal RPGR allele was associated with more severe disease. The XCI ratio in both blood and saliva was a predictor of visual function as measured by HVF diameter, rod amplitude, flicker amplitude, and flicker implicit time. For carriers with extreme XCI skewing of 80:20 or more, 57% were affected severely compared with 8% for those with XCI of less than 80:20 (P = 0.002).

CONCLUSIONS

Female carriers with mutations in RPGR demonstrate widely variable clinical severity. X-chromosome inactivation ratios correlate with clinical severity and may serve as a predictor of clinically significant disease. Because RPGR gene therapy trials are underway, a future imperative exists to determine which carriers require intervention and when to intervene. X-chromosome inactivation analysis may be useful for identifying candidates for early intervention.

Healthcare costs among patients with hemophilia A treated with factor replacement or bypassing agents

Objective: To assess real-world costs for patients with hemophilia A treated with bypassing agents versus factor VIII (FVIII) replacement. Methods: Claims data from a large US health insurer during 1 January 2006-30 September 2014 were used for analysis. Treated patients with hemophilia A were identified based on ≥1 medical claim with a diagnosis code for hemophilia A (ICD-9-CM 286.0) and ≥1 medical or pharmacy claim for bypassing therapy and/or FVIII replacement during 1 January 2007-31 August 2014. The bypassing therapy cohort comprised patients with ≥1 claim for bypassing therapy; all others were assigned to the factor replacement therapy cohort. Post-index hemophilia-related costs were computed as combined health plan plus patient paid amounts for medical claims with hemophilia A diagnosis code or hemophilia therapy procedure code (bypassing therapy, FVIII replacement therapy, desmopressin, antifibrinolytic therapy), as well as pharmacy claims for hemophilia therapy. Results: The study sample represented 580 patients: 50 (8.6%) in the bypassing therapy cohort (mean age: 38.5 years; mean post-index period: 2.1 years) and 530 (91.4%) in the factor replacement therapy cohort (mean age: 29.3 years; mean post-index period: 2.7 years). Compared with the factor replacement therapy cohort, mean per-patient-per-month hemophilia-related total costs were 4.8-fold higher in the bypassing therapy cohort ($57,232 vs. $11,899), comprising 4.4-fold higher medical costs ($45,911 vs. $10,352) and 7.3-fold higher outpatient pharmacy costs ($11,321 vs. $1547). Conclusions: Patients with hemophilia A treated with bypassing agents between 2007 and 2014 incurred substantially higher monthly hemophilia-related medical and pharmacy costs than patients treated only with FVIII replacement.

Prevalence of symptoms in hemophilia carriers in comparison with the general population: a systematic review

Introduction

Hemophilia is well known in males, but poorly recognized in hemophilia carriers, who may have a hemorrhagic tendency, and the symptoms may be frequent and severe. Few studies have been done evidencing this bleeding in female carriers of the hemophilia gene.

Objectives

To verify the prevalence of hemorrhagic symptoms in HC, compared to women in the general population.

Material and method

The articles published between October 1996 and November 2016 were searched in the PubMed, Scielo, Lilacs, Web of Science, Scopus and Cochrane Central databases.

Results and discussion

Seventy-five articles were found in electronic databases and 2 additional articles, through manual search in journal summaries and bibliographical references of other review articles. There is a limitation as to the number of studies that explore the association between the risk of hemorrhagic events and HC A or B. Among the few existing studies, there is a methodological difference, evidenced by control groups with distinct recruitments, divergent questionnaires and non-standardized concepts.

Conclusion

This review verified the existence of a higher prevalence of hemorrhagic symptoms in the HC in some outcomes, however, due to the limitations of the few studies found, there is still insufficient evidence to state that the HC has a greater hemorrhagic tendency in relation to the general population.

The Spectrum of Structural and Functional Abnormalities in Female Carriers of Pathogenic Variants in the RPGR Gene

Purpose

The purpose of this study was to investigate the phenotype and long-term clinical course of female carriers of RPGR mutations.

Methods

This was a retrospective cohort study of 125 heterozygous RPGR mutation carriers from 49 families.

Results

Eighty-three heterozygotes were from retinitis pigmentosa (RP) pedigrees, 37 were from cone-/cone-rod dystrophy (COD/CORD) pedigrees, and 5 heterozygotes were from pedigrees with mixed RP/CORD or unknown diagnosis. Mutations were located in exon 1-14 and in ORF15 in 42 of 125 (34%) and 83 of 125 (66%) subjects, respectively. The mean age at the first examination was 34.4 years (range, 2.1 to 86.0 years). The median follow-up time in heterozygotes with longitudinal data (n = 62) was 12.2 years (range, 1.1 to 52.2 years). Retinal pigmentary changes were present in 73 (58%) individuals. Visual symptoms were reported in 51 (40%) cases. Subjects with both symptoms and pigmentary fundus changes were older than the other heterozygotes (P = 0.01) and had thinner foveal outer retinas (P = 0.006). Complete expression of the RP or CORD phenotype was observed in 29 (23%) heterozygotes, although usually in milder forms than in affected male relatives. Best-corrected visual acuity (BCVA) was <20/40 and <20/400 in at least one eye in 45 of 116 (39%) and 11 of 116 (9%) heterozygotes, respectively. Myopia was observed in 74 of 101 (73%) subjects and was associated with lower BCVA (P = 0.006). Increasing age was associated with lower BCVA (P = 0.002) and decreasing visual field size (P = 0.012; I4e isopter).

Conclusions

RPGR mutations lead to a phenotypic spectrum in female carriers, with myopia as a significantly aggravating factor. Complete disease expression is observed in some individuals, who may benefit from future (gene) therapeutic options.

Evolving Complexity in Hemophilia Management

Rapid expansion of therapeutic options have increased the complexity of hemophilia care. Previously, on-demand therapy aimed to reduce morbidity and early mortality; however, now aggressive prophylaxis, particularly in children, encourages an active lifestyle. Accurate diagnosis, recognition of early threats to musculoskeletal health, and optimization of therapy are critical for both males and females affected by hemophilia. The diversity of emerging hemophilia therapies, from modified factor protein concentrates, to gene therapy, to nonfactor hemostatic strategies, provide an exciting opportunity to target unmet needs in the bleeding disorder community.