Consistent with biochemical studies, which identified domains in Lrp4 and MuSK that mediate their association, pathogenic autoantibodies to MuSK, which cause MG, bind the first Ig-like domain in MuSK, thereby inhibiting binding between Lrp4 and MuSK and reducing MuSK tyrosine phosphorylation [67,68]. The gene discussed is MUSK; the disease is myasthenia gravis.