A National Survey of Hereditary Angioedema and Acquired C1 Inhibitor Deficiency in the United Kingdom.

BACKGROUND: Detailed demographic data on people with hereditary angioedema (HAE) and acquired C1 inhibitor deficiency in the United Kingdom are relatively limited. Better demographic data would be beneficial in planning service provision, identifying areas of improvement, and improving care. OBJECTIVE: To obtain more accurate data on the demographics of HAE and acquired C1 inhibitor deficiency in the United Kingdom, including treatment modalities and services available to patients. METHODS: A survey was distributed to all centers in the United Kingdom that look after patients with HAE and acquired C1 inhibitor deficiency to collect these data. RESULTS: The survey identified 1152 patients with HAE-1/2 (58% female and 92% type 1), 22 patients with HAE with normal C1 inhibitor, and 91 patients with acquired C1 inhibitor deficiency. Data were provided by 37 centers across the United Kingdom. This gives a minimum prevalence of 1:59,000 for HAE-1/2 and 1:734,000 for acquired C1 inhibitor deficiency in the United Kingdom. A total of 45% of patients with HAE were on long-term prophylaxis (LTP) with the most used medication being danazol (55% of all patients on LTP). Eighty-two percent of patients with HAE had a home supply of acute treatment with C1 inhibitor or icatibant. A total of 45% of patients had a supply of icatibant and 56% had a supply of C1 inhibitor at home. CONCLUSIONS: Data obtained from the survey provide useful information about the demographics and treatment modalities used in HAE and acquired C1 inhibitor deficiency in the United Kingdom. These data are useful for planning service provision and improving services for these patients.

Outcomes following SARS-CoV-2 infection in patients with primary and secondary immunodeficiency in the UK.

In March 2020, the United Kingdom Primary Immunodeficiency Network (UKPIN) established a registry of cases to collate the outcomes of individuals with PID and SID following SARS-CoV-2 infection and treatment. A total of 310 cases of SARS-CoV-2 infection in individuals with PID or SID have now been reported in the UK. The overall mortality within the cohort was 17.7% (n = 55/310). Individuals with CVID demonstrated an infection fatality rate (IFR) of 18.3% (n = 17/93), individuals with PID receiving IgRT had an IFR of 16.3% (n = 26/159) and individuals with SID, an IFR of 27.2% (n = 25/92). Individuals with PID and SID had higher inpatient mortality and died at a younger age than the general population. Increasing age, low pre-SARS-CoV-2 infection lymphocyte count and the presence of common co-morbidities increased the risk of mortality in PID. Access to specific COVID-19 treatments in this cohort was limited: only 22.9% (n = 33/144) of patients admitted to the hospital received dexamethasone, remdesivir, an anti-SARS-CoV-2 antibody-based therapeutic (e.g. REGN-COV2 or convalescent plasma) or tocilizumab as a monotherapy or in combination. Dexamethasone, remdesivir, and anti-SARS-CoV-2 antibody-based therapeutics appeared efficacious in PID and SID. Compared to the general population, individuals with PID or SID are at high risk of mortality following SARS-CoV-2 infection. Increasing age, low baseline lymphocyte count, and the presence of co-morbidities are additional risk factors for poor outcome in this cohort.

Antibody Responses to SARS-CoV-2 Infection-Comparative Determination of Seroprevalence in Two High-Throughput Assays versus a Sensitive Spike Protein ELISA.

Robust assay development for SARS-CoV-2 serological testing requires assessment of asymptomatic and non-hospitalised individuals to determine if assays are sensitive to mild antibody responses. Our study evaluated the performance characteristics of two high-throughput SARS-CoV-2 IgG nucleocapsid assays (Abbott Architect and Roche) and The Binding Site (TBS) Anti-Spike IgG/A/M ELISA kit in samples from healthcare workers (HCWs). The 252 samples were collected from multi-site NHS trusts and analysed for SARS-CoV-2 serology. Assay performance was evaluated between these three platforms and ROC curves were used to redefine the Abbott threshold. Concordance between Abbott and TBS was 66%. Any discrepant results were analysed using Roche, which showed 100% concordance with TBS. Analysis conducted in HCWs within 58 days post-PCR result demonstrated 100% sensitivity for both Abbott and Roche. Longitudinal analysis for >100 days post-PCR led to sensitivity of 77.2% and 100% for Abbott and Roche, respectively. A redefined Abbott threshold (0.64) increased sensitivity to 90%, producing results comparable to TBS and Roche. The manufacturer's threshold set by Abbott contributes to lower sensitivity and elevated false-negative occurrences. Abbott performance improved upon re-optimisation of the cut-off threshold. Our findings provided evidence that TBS can be used as bespoke alternative for SARS-CoV-2 serology analysis where high-throughput platforms are not feasible on site.

Identification of a novel mutation in MAGT1 and progressive multifocal leucoencephalopathy in a 58-year-old man with XMEN disease.

XMEN disease (X-linked immunodeficiency with Magnesium defect, Epstein-Barr virus infection and Neoplasia) is a novel primary immune deficiency caused by mutations in MAGT1 and characterised by chronic infection with Epstein-Barr virus (EBV), EBV-driven lymphoma, CD4 T-cell lymphopenia, and dysgammaglobulinemia [1]. Functional studies have demonstrated roles for magnesium as a second messenger in T-cell receptor signalling [1], and for NKG2D expression and consequently NK- and CD8 T-cell cytotoxicity [2]. 7 patients have been described in the literature; the oldest died at 45 years and was diagnosed posthumously [1-3]. We present the case of a 58-year-old Caucasian gentleman with a novel mutation in MAGT1 with the aim of adding to the phenotype of this newly described disease by detailing his clinical course over more than 20 years.

Antibody deficiency secondary to chronic lymphocytic leukemia: Should patients be treated with prophylactic replacement immunoglobulin?

Hypogammaglobulinemia is a common finding in chronic lymphocytic leukemia (CLL). Its incidence increases with disease duration and stage such that it is present in up to 85 % of patients at some point in their disease course. It is therefore important to monitor patients for the development of an antibody deficiency. However, not all patients with antibody deficiency secondary to CLL are symptomatic with bacterial infections. In addition patients are susceptible to viral, fungal and opportunistic infections as a result of iatrogenic immunosuppression and through a variety of disease-related mechanisms, which affect cellular immunity and phagocytes. Published guidelines suggest that patients with a history of recurrent bacterial infections and a documented failure of antibody production should be treated with antibiotic prophylaxis in the first instance, with replacement immunoglobulin reserved for those who continue to suffer with significant bacterial infections. Here we present a review of the existing literature in order to provide a practical approach, based on best available evidence, to the investigation, monitoring and treatment of patients with antibody failure secondary to CLL; and we highlight areas in which further studies are needed.

Serum-free light-chain assay: clinical utility and limitations.

In the last decade, the introduction of the serum-free light-chain (sFLC) assay has been an important advance in the diagnosis and management of plasma cell dyscrasias, particularly monoclonal light-chain diseases. The immunoassay was developed to detect free light chains in serum by using anti-FLC antibodies which specifically recognised epitopes on light chains that were 'hidden' in intact immunoglobulins. Since its introduction in 2001, there have been several publications in the English language literature discussing the clinical utility as well as analytical limitations of the sFLC assay. These studies have highlighted both positive and negative aspects of the assay particularly with regard to its sensitivity and specificity and the technical challenges that can affect its performance. The contribution and significance of the sFLC assay in the management of light-chain myeloma, primary amyloid light-chain (AL) amyloidosis and non-secretory myeloma are well recognised and will be addressed in this review. The aim of this article is to also review the published literature with a view to providing a clear understanding of its utility and limitations in the diagnosis, prognosis and monitoring of plasma dyscrasias including intact immunoglobulin multiple myeloma (MM) and monoclonal gammopathy of unknown significance (MGUS). The increasing interest in using this assay in other haematological conditions will also be briefly discussed.

Striking intrafamilial phenotypic variability in Aicardi-Goutières syndrome associated with the recurrent Asian founder mutation in RNASEH2C.

Aicardi-Goutières syndrome (AGS) is an encephalopathy of early childhood which is most commonly inherited as an autosomal recessive trait. The disorder demonstrates significant genetic heterogeneity with causative mutations in five genes identified to date. Although most patients with AGS experience a severe neonatal or infantile presentation, poor neurodevelopmental outcome and reduced survival, clinical variability in the onset and severity of the condition is being increasingly recognized. A later presentation with a more variable effect on development, morbidity and mortality has been particularly observed in association with mutations in SAMHD1 and RNASEH2B. In contrast, the recurrent c.205C > T (p.R69W) RNASEH2C Asian founder mutation has previously only been identified in children with a severe AGS phenotype. Here, to our knowledge, we present the first report of marked phenotypic variability in siblings both harboring this founder mutation in the homozygous state. In this family, one female child had a severe AGS phenotype with an onset in infancy and profound developmental delay, whilst an older sister was of completely normal intellect with a normal head circumference and was only diagnosed because of the presence of chilblains and a mild hemiplegia. An appreciation of intrafamilial phenotypic expression is important in the counseling of families considering prenatal diagnosis, and may also be relevant to the assessment of efficacy in future clinical trials. In addition, marked phenotypic variation raises the possibility that more mildly affected patients are not currently identified.

Self-infusion programmes for immunoglobulin replacement at home: feasibility, safety and efficacy.

This review of the currently available literature from more than two decades of clinical experience with self-infusions of immunoglobulin at home provides evidence to support the feasibility, safety, and efficacy in all age groups. Self-infusions at home not only increase patient confidence and their understanding of the immune deficiency but also contribute to the improvement of health-related quality of life. Such home therapy programs should be encouraged, and wherever possible, experienced centers should extend their services to include patients who require immunoglobulin therapy for immunomodulation. Home therapy programs play an important role in long-term health outcome.