Hypomorphic CARD9 deficiency caused by p.Y91H results in adult-onset disease with variable penetrance and expressivity. Our findings establish the CARD9/RASGRF1/ERK/GM-CSF axis as critical to the pathophysiology of sCNSc.

Primary immunodeficiencies represent naturally occurring experimental models to decipher human immunobiology. We report a patient with combined immunodeficiency, marked by recurrent respiratory tract and DNA-based viral infections, hypogammaglobulinemia, and panlymphopenia. He also developed moderate neutropenia but without prototypical pyogenic infections. Using whole-exome sequencing, we identified a homozygous mutation in the inducible T cell costimulator ligand gene (ICOSLG; c.657C>G; p.N219K). Whereas WT ICOSL is expressed at the cell surface, the ICOSLN219K mutation abrogates surface localization: mutant protein is retained in the endoplasmic reticulum/Golgi apparatus, which is predicted to result from deleterious conformational and biochemical changes. ICOSLN219K diminished B cell costimulation of T cells, providing a compelling basis for the observed defect in antibody and memory B cell generation. Interestingly, ICOSLN219K also impaired migration of lymphocytes and neutrophils across endothelial cells, which normally express ICOSL. These defects likely contributed to the altered adaptive immunity and neutropenia observed in the patient, respectively. Our study identifies human ICOSLG deficiency as a novel cause of a combined immunodeficiency.

Introduction: Ready-to-use prefilled syringes for drug delivery are increasingly used across a broad spectrum of clinical specialties. For patients with primary immunodeficiencies manifesting as antibody deficiencies, immunoglobulin G (IgG) replacement therapy (IgRT) by subcutaneous administration is an established treatment modality. Expanding IgRT administration options through the introduction of prefilled syringes may further improve its utility. Areas covered: Here, we collate experience with prefilled syringes from other clinical settings to inform on their practicality and suitability for IgRT. In addition to discussing drug characteristics such as stability, pharmacokinetics, and efficacy, we focus on treatment delivery, physician/patient experience, costs, and the importance of education for the use of prefilled syringes. Expert opinion: Perceived benefits of prefilled syringes include accurate dosing, sterility, and reduced treatment time, while offering patients greater choice, convenience, and ease-of-use. Our review of clinical experience with prefilled syringes supports this consensus. Relatively few studies directly compare prefilled syringes with conventional administration, and robust studies of cost-effectiveness and health-related quality of life are needed on a drug-by-drug basis. Growth in the availability of prefilled syringes will continue, encouraged by the importance of patient choice and treatment convenience, toward the goal of individualized treatment regimens and improved quality of life.

Summary K E Y W O R D Sbi-allelic, candidiasis, CARD9, splicing

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