Research Article: Expanding the clinical spectrum of CD3? deficiency: comprehensive characterization of adult-onset disease and integrated reevaluation of all reported patients
Abstract:
CD3? deficiency is an ultrarare autosomal recessive inborn error of immunity characterized by immune dysregulation and variable immunodeficiency. To date, only 16 predominantly pediatric cases have been reported. Here, we describe two additional adult patients with CD3? deficiency and provide a comprehensive reevaluation of all previously published cases.
Clinical, immunological, and genetic investigations were performed in two adult patients presenting with immune dysregulation and hypogammaglobulinemia. Whole-genome sequencing was used to identify pathogenic CD3G variants, and protein expression was assessed by Western blot analysis. In addition, a literature review of all previously reported cases was conducted.
Both patients presented with humoral immunodeficiency and Evans syndrome responsive to rituximab therapy. One patient, currently the oldest reported individual with CD3? deficiency, harbored a novel homozygous frameshift variant in CD3G (c.213dupA, p.(Trp72Metfs*6)) resulting in complete loss of CD3? expression. Reevaluation of all reported cases demonstrated marked phenotypic heterogeneity, ranging from isolated autoimmune manifestations to severe early-onset combined immunodeficiency requiring hematopoietic stem cell transplantation. Notably, patients carrying identical deleterious variants exhibited substantial variability in clinical presentation and outcomes, indicating that no obvious genotype-phenotype correlation could be established based on the currently available data.
CD3? deficiency exhibits a broad and highly variable clinical spectrum extending into adulthood. Immune dysregulation, particularly autoimmune cytopenias, represents a prominent manifestation. Our findings expand the phenotypic spectrum of CD3? deficiency and emphasize the importance of considering this disorder also in adult patients with hypogammaglobulinemia and autoimmune disease.
Introduction:
The T cell receptor (TCR)/CD3 complex is a multisubunit structure essential for antigen recognition and T cell activation ( 1 ). It consists of a clonotypic TCR ?? heterodimer associated with invariant CD3 chains (?, ?, and ?) as well as the ?-? homodimer, which together ensure correct surface expression and intracellular signaling. Each CD3 chain contains one immunoreceptor tyrosine-based activation motif (ITAM) required for signal transduction, whereas the CD3? chain contains three ITAMs, thereby playing a…
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