A stone from another mountain can be used to attack the jade. Not much is known about the epidemiology of MS in mainland China, so we compiled the epidemiological features of MS in Europe. The traditional view is that the prevalence of MS increases with latitude, and the prevalence is higher than 30/100,000 in the northern United States, Canada, most of Europe, and Tasmania in Australia. Asian and African countries have a lower prevalence of about 5/100,000, and equatorial countries have a prevalence of less than 1/100,000. Orkney and northern Scotland have prevalence rates as high as 300 per 100,000. The results of some studies in recent years are not consistent with this, and there are areas of high MS prevalence in different areas of the islands of Sicily located in the Mediterranean Sea. There is a lack of epidemiological data on MS in China, but MS reports are increasing. There were 70 cases of MS in Peking Union Medical College Hospital from 1949-1977, accounting for 1.2% of neurology inpatients in the same period; 2.7% of inpatients in the same period from 1978-1979. 2/100,000 were surveyed in Yunnan Province in 1986, 2.3/100,000 were initially reported in Beijing in the early 1990s, and 10/100,000 were estimated in a survey in Rongqi Town, Guangdong Province in 1996. Epidemiological data on migration show that MS incidence decreases when people migrate from areas with high MS incidence to areas with low MS incidence; people who migrate from low incidence areas to high incidence areas maintain the low incidence characteristics of their place of birth; first generation black Caribbean and Asian immigrants to the UK maintain a lower incidence of MS compared to their UK-born next generation; migration before puberty is consistent with the incidence in their new country, and migration after puberty maintains the incidence in their original country. In one study, however, no significant difference in MS prevalence was found between immigrants from the UK and Ireland to Australia around the age of 15 years, presumably because time in the new environment was more important than age; the study from Israel found that offspring of immigrants from Asian and African countries had prevalence rates close to European levels, with an increased annual prevalence of MS in offspring whose parents immigrated to Israel more than 5 years before birth ( 2.3 per 100,000) and 0.9 per 100,000 for those less than 5 years, suggesting that the Israeli lifestyle increases the risk of MS in these offspring. There is a wide variation in MS racial susceptibility, with Black Americans, American Indians, Mexicans, Puerto Ricans, and Japanese having a low prevalence, male Black Americans having a nearly 40% lower risk of MS than whites, and the Sardinian population being a highly genetically susceptible population for MS. The risk of MS is higher in women than in men, but genomic studies have not identified MS-associated genes on the X chromosome. The high prevalence of MS in female patients may be related to the specific physiology of women and may be related to sex hormones, which may have an effect by regulating microglial cell function. Low-dose estrogen in the physiological state increases specific immune activity, while high-dose estrogen suppresses specific immune activity; progesterone has immunomodulatory effects and reduces inflammatory mediator production; pregnancy reduces MS relapse, especially in the second trimester of pregnancy when the relapse rate is lowest, while the relapse rate increases again in the first trimester after delivery.