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Review Article

Current overview of myasthenia gravis and

experience in China

Jun Guo, Dan Dang, Hong-Zeng Li, Zhu-Yi Li
Department of Neurology, Tangdu Hospital, Fourth Military Medical University, Xi’an 710038, Shaanxi, China.

ABSTRA CT
Myasthenia gravis (MG) is an acquired autoimmune disease affecting synaptic transmission via the neuromuscular junction mainly
due to the presence of auto‑antibodies targeting acetylcholine receptors. Ocular or generalized MG is clinically diagnosed when the
extra‑ocular muscles or other muscle groups beyond the extra‑ocular muscles are involved. MG occurs in both sexes at any ages
from all races but shows a wide variability in incidence and prevalence. Differences in clinical phenotypes of MG patients between
West and East countries have been observed. Herein, we review the current concept on epidemiology, classification, and generalized
progression in MG, mainly focusing on the differential features from mainland China.
Key words: Classification, epidemiology, generalization, myasthenia gravis

INTRODUCTION EPIDEMIOLOGY

Myasthenia gravis (MG) is known as an autoimmune It is well known that MG occurs worldwide affecting
disease mainly mediated by auto‑antibodies against both males and females at any ages as shown in an
the acetylcholine receptors (AChR) between the epidemiological study with a large sample size.
[6]
synaptic space of the skeletal muscles, leading to an However, the incidence and prevalence of MG are
impairment of the neuromuscular transmission and characterized by marked variation, depending on
corresponding clinical symptoms such as fluctuating the time and/or the location of studies. A national
muscle weakness and fatigability. According to epidemiological study in Australia has shown that
[1]
clinical symptoms, MG is divided into ocular MG the annual crude incidence and prevalence rates of
and generalized MG. Secondary generalization of MG were 24.9 and 117.1/million, respectively. Other
[7]
clinical symptoms is common in MG, resulting in a two population‑based studies have been conducted in
poor prognosis for patients and a tremendous burden Taiwan and Norway. The reported annual incidence
for families and society. Although epidemiological and prevalence of MG were 21 and 84‑140/million
[2]
studies have shown that all the races worldwide in Taiwan, and 16 and 131/million in Norway.
[8]
[9]
can be affected, differences between Caucasian and Moreover, the estimated annual incidence rate of MG
Asian patients were found in relation to clinical is 30/million in central London, [10] 24/million in Ferrara
phenotypes. [3‑5] In this mini‑review, we address the province of Italy, [11] and 21.3/1 million in Barcelona of
current concepts of MG, including epidemiology, Spain. [12] Unfortunately, no national population‑based
classification of clinical subtypes, and secondary epidemiological studies of MG have been conducted
generalization. We also focus on the different clinical in mainland China. To obtain pooled data from a larger
features of MG in China. sample, Carr et al. have collated 55 studies performed
[6]
between 1950 and 2007, representing 1.7 billion
Access this article online population‑years. By utilizing the meta‑analysis,
Quick Response Code: they have estimated that the annual incidence and
Website: prevalence rates of MG were 5.3 (range: 1.7‑21.3) and
www.nnjournal.net
77.7/million (15‑179), respectively.
DOI:
10.4103/2347-8659.143664 The onset of MG may be influenced by sex and age.
Regardless of age, the crude incidences of females

Corresponding Author: Dr. Zhu-Yi Li, Department of Neurology, Tangdu Hospital, Fourth Military Medical University,
Xi’an 710038, Shaanxi, China. E-mail: lizhuyi@fmmu.edu.cn

Neuroimmunol Neuroinflammation | Volume 1 | Issue 3 | December 2014 127