Bruton's tyrosine kinase is implicated in X-linked gammaglobulinemia (XLA). Its exact mechanism of action remains unknown, but it plays a crucial role in B cell maturation. XLA patients have normal pre-B cell populations in their bone marrow but these cells fail to mature and enter the circulation. At least 24 mutations of the btk gene have been identified. Hugo is a masculine name. ... The Entrez Global Query Cross-Database Search System allows access to databases at the National Center for Biotechnology Information (NCBI) website. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... The National Center for Biotechnology Information (NCBI) is part of the US National Library of Medicine (NLM), which is a branch of the US National Institutes of Health. ... Swiss-Prot is a curated biological database of protein sequences created in 1986 by Amos Bairoch during his PhD and developed by the Swiss Institute of Bioinformatics and the European Bioinformatics Institute. ... The Protein Data Bank (PDB) is a repository for 3-D structural data of proteins and nucleic acids. ... The Enzyme Commission number (EC number) is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze. ... In biology and evolutionary computation, a locus is the position of a gene (or other significant sequence) on a chromosome. ... Tyrosine kinases are a subclass of protein kinase, see there for the principles of protein phosphorylation A tyrosine kinase (EC 2. ... Wikipedia does not yet have an article with this exact name. ... B cells are lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response). ... Grays Anatomy illustration of cells in bone marrow. ...