Complex sentence: Another nRTK, Btk, is also involved in signaling mediated by B-cell receptor, mutations in the Btk gene are responsible for X-linked agammaglobulinemia.
Split into simpler sentences: Another nRTK, Btk, is also involved in signaling mediated by B-cell receptor. Mutations in the Btk gene are responsible for X-linked agammaglobulinemia.