Background As of November 2020, SARS-CoV-2 has resulted in 55 million infections worldwide and over 1.3 million deaths from COVID-19. Outcomes following SARS-CoV-2 infection in individuals with primary immunodeficiency or symptomatic secondary immunodeficiency remain uncertain. Objectives To document the outcomes of individuals with primary or symptomatic secondary immunodeficiency following COVID-19 in the United Kingdom. Methods At the start of the COVID-19 pandemic, the United Kingdom Primary Immunodeficiency Network (UK PIN) established a registry of cases to collate the nationwide outcomes of COVID-19 in individuals with PID or symptomatic SID and determine risk factors associated with morbidity and mortality from COVID-19 in these patient groups. Results 100 patients had been enrolled by 1st July 2020, 60 with primary immunodeficiency (PID), 7 with other inborn errors of immunity including autoinflammatory diseases and C1 inhibitor deficiency and 33 with symptomatic secondary immunodeficiency (SID). In individuals with PID, 53.3% (n=32/60) were hospitalized, the infection fatality rate (IFR) was 20.0% (n=12/60), the case fatality rate (CFR) was 31.6% (n=12/38) and the inpatient mortality 37.5% (n=12/32). Individuals with SID had worse outcomes than those with PID. 75.8% (n=25/33) were hospitalized, the IFR was 33.3% (n=11/33), the CFR was 39.2% (n=11/28), and inpatient mortality 44.0% (n=11/25). Conclusions In comparison to the general population, adult patients with PID and symptomatic SID display greater morbidity and mortality from COVID-19. This increased risk must be reflected in public health guidelines to adequately protect vulnerable patients from exposure to the virus.

BackgroundThe genetic cause of primary immunodeficiency disease (PID) carries prognostic information.ObjectiveWe conducted a whole-genome sequencing study assessing a large proportion of the NIHR BioResource–Rare Diseases cohort.MethodsIn the predominantly European study population of principally sporadic unrelated PID cases (n = 846), a novel Bayesian method identified nuclear factor κB subunit 1 (NFKB1) as one of the genes most strongly associated with PID, and the association was explained by 16 novel heterozygous truncating, missense, and gene deletion variants. This accounted for 4% of common variable immunodeficiency (CVID) cases (n = 390) in the cohort. Amino acid substitutions predicted to be pathogenic were assessed by means of analysis of structural protein data. Immunophenotyping, immunoblotting, and ex vivo stimulation of lymphocytes determined the functional effects of these variants. Detailed clinical and pedigree information was collected for genotype-phenotype cosegregation analyses.ResultsBoth sporadic and familial cases demonstrated evidence of the noninfective complications of CVID, including massive lymphadenopathy (24%), unexplained splenomegaly (48%), and autoimmune disease (48%), features prior studies correlated with worse clinical prognosis. Although partial penetrance of clinical symptoms was noted in certain pedigrees, all carriers have a deficiency in B-lymphocyte differentiation. Detailed assessment of B-lymphocyte numbers, phenotype, and function identifies the presence of an increased CD21low B-cell population. Combined with identification of the disease-causing variant, this distinguishes between healthy subjects, asymptomatic carriers, and clinically affected cases.ConclusionWe show that heterozygous loss-of-function variants in NFKB1 are the most common known monogenic cause of CVID, which results in a temporally progressive defect in the formation of immunoglobulin-producing B cells.

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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 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.

Next-generation sequencing has been invaluable in the elucidation of the genetic etiology of many subtypes of intellectual disability in recent years. Here, using exome sequencing and whole-genome sequencing, we identified three de novo truncating mutations in WAS protein family member 1 (WASF1) in five unrelated individuals with moderate to profound intellectual disability with autistic features and seizures. WASF1, also known as WAVE1, is part of the WAVE complex and acts as a mediator between Rac-GTPase and actin to induce actin polymerization. The three mutations connected by Matchmaker Exchange were c.1516C>T (p.Arg506Ter), which occurs in three unrelated individuals, c.1558C>T (p.Gln520Ter), and c.1482delinsGCCAGG (p.Ile494MetfsTer23). All three variants are predicted to partially or fully disrupt the C-terminal actin-binding WCA domain. Functional studies using fibroblast cells from two affected individuals with the c.1516C>T mutation showed a truncated WASF1 and a defect in actin remodeling. This study provides evidence that de novo heterozygous mutations in WASF1 cause a rare form of intellectual disability.