The protein encoded by this gene plays a crucial role in B-cell development. Mutations in this gene cause X-linked agammaglobulinemia type 1, which is an immunodeficiency characterized by the failure to produce mature B lymphocytes, and associated with a failure of Ig heavy chain rearrangement. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Dec 2013],AGMX1,AT,ATK,BPK,IMD1,PSCTK1,XLA,BTK,Apoptosis,B Cell Receptor Signaling Pathway,Cell Biology & Developmental Biology,Cell Intrinsic Innate Immunity Signaling Pathway,Immunology & Inflammation,Innate Immunity_TLR Signaling,Kinase,Kinase_Tyrosine kinases,Protein phosphorylation,Signal Transduction,Toll-like Receptor Signaling Pathway,BTK