Definition
B-cell linker protein (BLNK) deficiency (OMIM #613502) is a rare primary immunodeficiency characterized by reduced serum levels of all immunoglobulin classes in the absence of peripheral B cells (peripheral B cells <2%). To date, a small number of patients have been described. BLNK deficiency is caused by biallelic deleterious mutations in the gene encoding for BLNK.
Pathogenesis
Early B cell development takes place in the bone marrow. An important maturational step is the progression form the pro-B to the pre-B stage (Espeli et al. 2006; Rudin and Thompson 1998; Bartholdy and Matthias 2004). This passage depends on the expression of a functional B cell receptor composed of the μ heavy chain (IGHM; OMIM*147020), Igα (CD79A; OMIM*112205), Igβ (CD79B; OMIM*147245), VpreB, and λ5 (IGLL1; OMIM*146770) that initiates downstream signalling necessary for early B cell differentiation through kinases such as BTK and BLNK (OMIM*604615). Over the years, animal models and in vitro...
References
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Lougaris, V., Plebani, A. (2019). BLNK Deficiency. In: MacKay, I., Rose, N. (eds) Encyclopedia of Medical Immunology. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-9209-2_18-1
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DOI: https://doi.org/10.1007/978-1-4614-9209-2_18-1
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