ORAI1 mutations abolishing store-operated Ca

BACKGROUND: Store-operated Ca OBJECTIVE: We performed molecular and immunologic analysis of patients with CID, anhidrosis, and ectodermal dysplasia of unknown etiology. METHODS: We performed DNA sequencing of the ORAI1 gene, modeling of mutations on ORAI1 crystal structure, analysis of ORAI1 mRNA and protein expression, SOCE measurements, immunologic analysis of peripheral blood lymphocyte populations by using flow cytometry, and histologic and ultrastructural analysis of patient tissues. RESULTS: We identified 3 novel autosomal recessive mutations in ORAI1 in unrelated kindreds with CID, autoimmunity, ectodermal dysplasia with anhidrosis, and muscular dysplasia. The patients were homozygous for p.V181SfsX8, p.L194P, and p.G98R mutations in the ORAI1 gene that suppressed ORAI1 protein expression and SOCE in the patients\u27 lymphocytes and fibroblasts. In addition to impaired T-cell cytokine production, ORAI1 mutations were associated with strongly reduced numbers of invariant natural killer T and regulatory T (Treg) cells and altered composition of γδ T-cell and natural killer cell subsets. CONCLUSION: ORAI1 null mutations are associated with reduced numbers of invariant natural killer T and Treg cells that likely contribute to the patients\u27 immunodeficiency and autoimmunity. ORAI1-deficient patients have dental enamel defects and anhidrosis, representing a new form of anhidrotic ectodermal dysplasia with immunodeficiency that is distinct from previously reported patients with anhidrotic ectodermal dysplasia with immunodeficiency caused by mutations in the nuclear factor κB signaling pathway (IKBKG and NFKBIA)

Variable impairment of platelet functions in patients with severe, genetically linked immune deficiencies.

In patients with dysfunctions of the Ca2+ channel ORAI1, stromal interaction molecule 1 (STIM1) or integrin-regulating kindlin-3 (FERMT3), severe immunodeficiency is frequently linked to abnormal platelet activity. In this paper, we studied in nine rare patients, including relatives, with confirmed genetic mutations of ORAI1, STIM1 or FERMT3, platelet responsiveness by multi-parameter assessment of whole blood thrombus formation under high-shear flow conditions. In platelets isolated from 5 out of 6 patients with ORAI1 or STIM1 mutations, store-operated Ca2+ entry (SOCE) was (in)completely defective compared to control platelets. Parameters of platelet adhesion and aggregation on collagen microspots were impaired for 4/6 patients, in part related to a low platelet count. For 4 patients, platelet adhesion/aggregation and procoagulant activity on VWF/rhodocytin and VWF/fibrinogen microspots were impaired, independently of platelet count and partly correlated with SOCE deficiency. Measurement of thrombus formation at low shear rate confirmed a larger impairment of platelet functionality in the ORAI1 patients than in the STIM1 patient. For 3 patients/relatives with a FERMT3 mutation, all parameters of thrombus formation were strongly reduced regardless of the microspot. Bone marrow transplantation, required by two patients, resulted in overall improvement of platelet function. We concluded that multiparameter assessment of whole-blood thrombus formation, in a surface-dependent way, can detect: (i) additive effects of low platelet count and impaired platelet functionality; (ii) aberrant ORAI1-mediated Ca2+ entry; (iii) differences in platelet activation between patients carrying the same ORAI1 mutation; (iv) severe platelet function impairment linked to a FERMT3 mutation and bleeding history