Anti-LRP4 autoantibodies in Chinese patients with myasthenia gravis.

INTRODUCTION: We assessed antibodies against low-density lipoprotein receptor-related protein 4 (LRP4-Ab) in a Chinese population with myasthenia gravis (MG). METHODS: Serum samples from 116 patients and 80 controls were collected. Acetylcholine receptor antibodies(AChR-Ab) and muscle-specific receptor tyrosine kinase antibodies (MuSK-Ab) were tested using an enzyme-linked immune absorption assay, and LRP4-Ab was identified using a cell-based assay. MG patients with neither AChR-Ab nor MuSK-Ab were defined as double-seronegative MG (dSN-MG). RESULTS: Two of 116 (1.7%) of all patients and 2 of 50 (1%) dSN-MG patients were positive for LRP4-Ab. These 2 patients had ocular MG. Following treatment with acetylcholinesterase inhibitor and prednisone, both achieved full remission. CONCLUSIONS: This study shows that LRP4-Ab is a pathogenic antibody in MG. LRP4-MG seems to be characterized by mild disease severity and favorable therapeutic effect in contrast with other types of MG. Muscle Nerve 56: 938-942, 2017.

Low frequency repetitive nerve stimulation in anti-muscle specific tyrosine kinase receptor antibody positive myasthenia gravis / 中华神经科杂志

Objective To describe the repetitive nerve stimulation ( RNS) in anti-muscle specific tyrosine kinase (anti-MuSK) receptor antibody positive myasthenia gravis (MG), and compare with anti-acetylcholine receptor ( AChR ) positive myasthenia gravis , to figure out characteristics of anti-MuSK receptor MG.Methods We analyzed clinical and RNS data of nine anti-MuSK receptor MG and 19 age-and sex-matched anti-AChR MG.RNS was performed to the abductor digiti minimi , orbicularis oculi or musculus frontalis and trapezius .Results In anti-MuSK receptor MG , abnormal RNS in facial nerve was seen in 6/9 and in trapezius was 5/9, in limbs was 0.In anti-AChR MG, abnormal RNS in facial nerve was seen in 13/19, in trapezius was 18/19 and in limbs was 7/19.Abnormal in any of three parts was 8/9 and 19/19 in anti-MuSK receptor MG and anti-AChR MG, respectively.The RNS decrementing was more obvious in facial nerve in anti-Musk receptor MG than in anti-AChR MG.Negative prostigmin test was independently associated with anti-MuSK receptor MG (OR=4.25,95% CI 2.19 -15.25, P=0.015). Conclusions Abnormal RNS in any of three parts is more pronounced in anti-AChR MG compared with anti-MuSK receptor MG.RNS decrementing in facial nerve is more obvious in anti-AChR MG.Negative prostigmin test can aid in early suspicion in anti-MuSK receptor MG.

Low frequency repetitive nerve stimulation in anti-muscle specific tyrosine kinase receptor antibody positive myasthenia gravis / 中华神经科杂志

Objective To describe the repetitive nerve stimulation ( RNS) in anti-muscle specific tyrosine kinase (anti-MuSK) receptor antibody positive myasthenia gravis (MG), and compare with anti-acetylcholine receptor ( AChR ) positive myasthenia gravis , to figure out characteristics of anti-MuSK receptor MG.Methods We analyzed clinical and RNS data of nine anti-MuSK receptor MG and 19 age-and sex-matched anti-AChR MG.RNS was performed to the abductor digiti minimi , orbicularis oculi or musculus frontalis and trapezius .Results In anti-MuSK receptor MG , abnormal RNS in facial nerve was seen in 6/9 and in trapezius was 5/9, in limbs was 0.In anti-AChR MG, abnormal RNS in facial nerve was seen in 13/19, in trapezius was 18/19 and in limbs was 7/19.Abnormal in any of three parts was 8/9 and 19/19 in anti-MuSK receptor MG and anti-AChR MG, respectively.The RNS decrementing was more obvious in facial nerve in anti-Musk receptor MG than in anti-AChR MG.Negative prostigmin test was independently associated with anti-MuSK receptor MG (OR=4.25,95% CI 2.19 -15.25, P=0.015). Conclusions Abnormal RNS in any of three parts is more pronounced in anti-AChR MG compared with anti-MuSK receptor MG.RNS decrementing in facial nerve is more obvious in anti-AChR MG.Negative prostigmin test can aid in early suspicion in anti-MuSK receptor MG.