肌肉特异性受体酪氨酸激酶抗体阳性重症肌无力

目的 探讨不同血清抗体重症肌无力(MG)的临床特征.方法 用荧光免疫沉淀法(FIPA)和荧光免疫细胞染色法(CBA)检测119例MG患者血清乙酰胆碱受体抗体(AChR-Ab)和肌肉特异性受体酪氨酸激酶抗体(MuSK-Ab)水平.比较AChR-Ab阳性、MuSK-Ab阳性、血清抗体阴性MG的临床特征.结果 纳入119例患者中,90例AChR-Ab阳性(75.6%),29例阴性:其中5例MuSK-Ab阳性(17.2%),24例血清抗体阴性(82.8%).AChR-Ab阳性、MuSK-Ab阳性和血清抗体阴性MG 3组比较,男女比例和平均发病年龄差异均无统计学意义.3例MuSK-Ab阳性的患者主要表现为延髓肌受累;79.2%(19/24)的血清抗体阴性MG患者表现为美国MG协会(MGFA)Ⅰ型;2例MuSK-Ab阳性的患者MGFA≥Ⅲ型;MuSK-Ab滴度水平与患者病情严重程度相关(r=0.941,P=0.014);MuSK-Ab阳性的患者均未发现有胸腺的异常.结论 MuSK-Ab仅出现在AChR-Ab阴性患者的血清中.MuSK-Ab阳性的患者主要表现为延髓肌受累,病情较重且不伴有胸腺的病变.MuSK-Ab阳性的MG可能是不同于血清AChR-Ab阳性的MG的又一亚型.

Myasthenia gravis with muscle specific receptor tyrosine kinase antibodies

Objectives To compare the characteristics of myasthenia gravis (MG) with different antibodies.Methods The muscle specific receptor tyrosine kinase (MuSk) and acetylcholine receptor (AChR) antibodies were detected in the sera of 119 MG patients,and fluoroimmunoprecipitation assay and cell based assay were applied. The clinical features of AChR-Ab positive,MuSK-Ab positive and serum negative MG patients were compared.Results There were 90 AChR-Ab positive sera tested out from the 119 MG sera,and 5 sera found with MuSK-Ab in the 29 AChR-Ab negative sera.There was no significant difference among the three groups regarding sex and age at onset.There were 3/5 of MuSK-Ab positive patients with predominantly bulbar paralysis,2/5 of MuSK-Ab positive patients were classified as MGFA Ⅲ to Ⅴ,and 79.2% (19/24) of serum negative patients were classified as MGFA Ⅰ.There was significantly positive relation between the levels of MuSK antibodies and disease severity (r=0.941,P=0.014).Neither thymic hyperplasia nor hymoma were found in MuSK-Ab positive patients.Conclusions MuSK antibodies are only detected out in the sera without AChR-Ab.The MuSK-Ab positive patients are mainly involved bulbar muscles,and without thymus abnormality.MuSK-MG is different with the AChR MG.