A novel frameshift variant in TNFRSF13B in a Chinese patient with late-onset combined immunodeficiency

Dear Editor, The TNFRSF13B gene encodes transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI), one of the TNF receptor superfamily members combining with co-stimulation factors B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL). TACI plays a crucial role in terminal maturation of B cells and in the class-switching of immunoglobulins, and abnormalities in TACI might cause common variable immunodeficiency (CVID) [1]. However, no attention has been paid to TACI variants in combined immunodeficiency (CID) patients, although TACI is also expressed by the activated T cells [2]. Here, we make the first report of a novel frameshift TNFRSF13B variant identified in a CVID-like patient with prominent reduction in CD19+B cells, NK cells, CD3+T cells, CD8+T cells and naïve CD4+T cells, who was (finally) diagnosed as having late-onset combined immunodeficiency (LOCID). A 35-year-old Chinese Han woman diagnosed as having ITP at the age of 23 was treated with prednisone orally for several months at the time of diagnosis. At age 32, she complained of lower limb oedema with ascites, portal hypertension, hepatosplenomegaly and lymphadenopathy, and she was treated with diuretics. Recently, the patient was admitted to our hospital for intermittent chest pain with a virtual reference station about 4–5. The symptom of fatigue was also obvious. The patient has suffered from ecchymosis ever since childhood, and has also had a 5-year history of chronic sinusitis and pharyngitis with mild symptoms.