In studies from various countries, including France, Germany, the Netherlands, Colombia, Japan, and China, mutations in TMEM240 have been linked to spinocerebellar ataxia 21 (SCA21), leading to cognitive impairment and movement disorders, suggesting that the pathogenic mechanism underlying SCA21 may involve early gliosis and lysosomal impairment caused by mutant TMEM240 [23–27]. This evidence concerns the gene TMEM240 and spinocerebellar ataxia type 21.