TSEN54 and pontocerebellar hypoplasia: More importantly, recessive mutations in the genes of three subunits (TSen2, TSen34, and TSen54) cause pontocerebellar hypoplasia (PCH) types 2A-C, 4, and 5 (Budde et al., 2008; Namavar et al., 2011a,b; Bierhals et al., 2013; Maraş-Genç et al., 2015).