UDP-N-acetylglucosamine transferase subunit ALG14 homolog (ALG14) forms a complex with ALG13 protein and is required for the addition of the second N-acetylglucosamine (GlcNAc) to the lipid linked oligosaccharide (LLO) intermediate (GlcNAcDOLDP) (Gao et al. 2005). Defects in ALG14 can cause congenital myasthenic syndrome (ALG14-CMS), which is due to a defect in neuromuscular signal transmission (Cossins et al. 2013). The most commonly affected muscles include proximal limb muscles. Mutations causing ALG14-CMS include p.P65L and p.R104* (Cossins et al. 2013).