COG6  CDG-IIl (COG6-CDG) Shaheen syndrome (SHNS)  Ataxia, cerebral atrophy, developmental delay, epilepsy, hypotonia, optic nerve atrophy, sensoneural hearing loss Intellectual disability  Lübbehusen et al., 2010; Huybrechts et al., 2012; Shaheen et al., 2013; Rymen et al., 2015