Taken together, we identified a novel interaction between MuSK and CaMK2β and at the same time, excluded defective MuSK kinase regulation as a possible cause of NMJ fragmentation in Mbnl1ΔE3/ΔE3 mice or ataxia in Camk2bΔE2/ΔE2 mice. The gene discussed is MUSK; the disease is Ataxia.