Clinical Analysis Of Chinese Anti-low-density-lipoprotein-receptor-associated Protein 4 Antibodies In Patients With Myasthenia Gravis

ObjectiveIn recent years,low-density lipoprotein receptor-associated protein 4(LRP4)antibodies have been identified as new MG autoantibodies.In serum-negative MG patients without AChR and MuSK antibodies,the detection rate of LRP4-Ab is 2%-50%.LRP4-MG data are reported at this stage,and the clinical characteristics of this new antibody have not been fully defined.This article will expand the sample size to explore the clinical characteristics of LRP4-MG patients in China.MethodCollected nearly 3,000 suspected MG serum samples and clinical data from 19 provinces/municipalities in China.AChR-Ab and Titin-Ab were detected by ELISA,and MuSK-Ab and LRP4-Ab were detected by cell-based assays(CBA).According to the MG diagnostic criteria,2172 patients were finally diagnosed with MG.The clinical characteristics of MG patients with LRP4 antibody MG were summarized and clinical analysis was performed on different antibody subgroups of MG.Result(1)The total frequency of related antibodies in 21 72 MG patients was 75.28%AChR-Ab,4.14%MuSK-Ab,0.74%LRP4-Ab,16.79%Titin-Ab.In the serum-negative MG,the MuSK antibody was 15.27%;in the double-negative MG,the LRP4 antibody was 2.86%.Among 13 cases of LRP4-MG,the ratio of male to female was 1:1.6(5/8),which was more frequent in women,and the age of onset was younger,with 53.8%(7/13)of the lower age group(<14 years).(2)75.0%LRP4-MG was first in the ophthalmic muscle,and 3 cases were first in the limb band muscle.The bulbar and cervical muscles were not the first.The ratio of LRP4-MG of pure ocular muscle type is relatively high.In one case,respiratory muscles were involved,and up to 91.7%could affect ocular muscles.No thymoma was found in any of the 12 LRP4-MG patients.(3)90.0%of LRP4-MG patients were effective on bromide,and 87.5%of LRP4-MG also had good effects on prednisone.LRP4-MG also showed a good prognosis,with a complete remission reaching 41.7%.LRP4-MG is effective for drug effects,usually has a good prognosis,rarely worsens and is ineffective.ConclusionBy expanding the sample,it was verified that the positive rate of LRP4-Ab in China was lower than that in Western countries.LRP4-MG is different from other MG non-antibody groups in clinical characteristics.Most of LRP4-MG patients are women,and the proportion of low-age group(?14 years)is high.LRP4-MG is rarely associated with thymoma,most of which are the first symptom of the eye muscles.The symptoms often only affect the eye muscles and limb band muscles,and the symptoms are mild.Patients with LRP4-MG have an effect on both bromazepine and prednisone,and the prognosis is good.