Activated phosphoinositide 3-kinase (PI3K) δ Syndrome (APDS), caused by
autosomal dominant mutations in PIK3CD (APDS1) or
PIK3R1 (APDS2), is a heterogeneous primary immunodeficiency.
While initial cohort-descriptions summarized the spectrum of clinical and
immunological manifestations, questions about long-term disease evolution and
response to therapy remain. The prospective European Society for Immunodeficiencies
(ESID)-APDS registry aims to characterize the disease course, identify outcome
predictors, and evaluate treatment responses. So far, 77 patients have been recruited
(51 APDS1, 26 APDS2). Analysis of disease evolution in the first 68 patients
pinpoints the early occurrence of recurrent respiratory infections followed by
chronic lymphoproliferation, gastrointestinal manifestations, and cytopenias.
Although most manifestations occur by age 15, adult-onset and asymptomatic courses
were documented. Bronchiectasis was observed in 24/40 APDS1 patients who received a
CT-scan compared with 4/15 APDS2 patients. By age 20, half of the patients had
received at least one immunosuppressant, but 2–3 lines of immunosuppressive
therapy were not unusual before age 10. Response to rapamycin was rated by physician
visual analog scale as good in 10, moderate in 9, and poor in 7. Lymphoproliferation
showed the best response (8 complete, 11 partial, 6 no remission), while bowel
inflammation (3 complete, 3 partial, 9 no remission) and cytopenia (3 complete, 2
partial, 9 no remission) responded less well. Hence, non-lymphoproliferative
manifestations should be a key target for novel therapies. This report from the
ESID-APDS registry provides comprehensive baseline documentation for a growing cohort
that will be followed prospectively to establish prognostic factors and identify
patients for treatment studies.
IL-6 excess is central to the pathogenesis of multiple inflammatory conditions and is targeted in clinical practice by immunotherapy that blocks the IL-6 receptor encoded by IL6R. We describe two patients with homozygous mutations in IL6R who presented with recurrent infections, abnormal acute-phase responses, elevated IgE, eczema, and eosinophilia. This study identifies a novel primary immunodeficiency, clarifying the contribution of IL-6 to the phenotype of patients with mutations in IL6ST, STAT3, and ZNF341, genes encoding different components of the IL-6 signaling pathway, and alerts us to the potential toxicity of drugs targeting the IL-6R.
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Primary immunodeficiency (PID) is characterised by recurrent and often life-threatening infections, autoimmunity and cancer, and it presents major diagnostic and therapeutic challenges. Although the most severe forms present in early childhood, the majority of patients present in adulthood, typically with no apparent family history and a variable clinical phenotype of widespread immune dysregulation: about 25% of patients have autoimmune disease, allergy is prevalent, and up to 10% develop lymphoid malignancies
1
–
3
. Consequently, in sporadic PID genetic diagnosis is difficult and the role of genetics is not well defined. We addressed these challenges by performing whole genome sequencing (WGS) of a large PID cohort of 1,318 participants. Analysis of coding regions of 886 index cases found disease-causing mutations in known monogenic PID genes in 10.3%, while a Bayesian approach (BeviMed
4
) identified multiple potential new candidate genes, including
IVNS1ABP
. Exploration of the non-coding genome revealed deletions in regulatory regions which contribute to disease causation. Finally, a genome-wide association study (GWAS) identified PID-associated loci and uncovered evidence for co-localisation of, and interplay between, novel high penetrance monogenic variants and common variants (at the
PTPN2
and
SOCS1
loci). This begins to explain the contribution of common variants to variable penetrance and phenotypic complexity in PID. Thus, a cohort-based WGS approach to PID diagnosis can increase diagnostic yield while deepening our understanding of the key pathways influencing human immune responsiveness.
Once-daily oral administration of BCX7353 at a dose of 125 mg or more resulted in a significantly lower rate of attacks of hereditary angioedema than placebo. Mild gastrointestinal symptoms were the principal side effect. (Funded by BioCryst Pharmaceuticals; APeX-1 ClinicalTrials.gov number, NCT02870972 .).
Primary immunodeficiencies (PIDs) are rare monogenic inborn errors of immunity that result in impairment of functions of the human immune system. PIDs have a broad phenotype with increased morbidity and mortality, and treatment choices are often complex. With increased accessibility of next-generation sequencing (NGS), the rate of discovery of genetic causes for PID has increased exponentially. Identification of an underlying monogenic diagnosis provides important clinical benefits for patients with the potential to alter treatments, facilitate genetic counselling, and pre-implantation diagnostics. We investigated a NGS PID panel of 242 genes within clinical care across a range of PID phenotypes. We also evaluated Phenomizer to predict causal genes from human phenotype ontology (HPO) terms. Twenty-seven participants were recruited, and a total of 15 reportable variants were identified in 48% (13/27) of the participants. The panel results had implications for treatment in 37% (10/27) of participants. Phenomizer identified the genes harbouring variants from HPO terms in 33% (9/27) of participants. This study shows the clinical efficacy that genetic testing has in the care of PID. However, it also highlights some of the disadvantages of gene panels in the rapidly moving field of PID genomics and current challenges in HPO term assignment for PID.
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