TTC19 and cerebellar ataxia: Furthermore, patients with homozygous mutations in another assembly factor TTC19 (tetratricopeptide repeat domain 19), such as p.L219*, p.E173*, are found to develop a series of neurodegenerative disorders, including severe psychiatric symptoms, cerebellar ataxia, cognitive impairment, LS and so on (Ghezzi et al., 2011; Atwal, 2013; Malek et al., 2018; Habibzadeh et al., 2019).