Golgi enzymes involved in N-glycan processing are critical for brain development, deficiencies in many leads to congenital disorders of glycosylation (CDG) with multisystem effects, particularly affecting the brain. Our study presents the first report of pathogenic variants in MAN2A2, causing a novel autosomal recessive CDG with neurological involvement. We identified a multiplex consanguineous family with a homozygous truncating variant, p.Val1101Ter in MAN2A2. Here, we also present the development of a cell-based complementation assay to assess the pathogenicity of MAN2A2 variants, which can also be extended to MAN2A1 variants for future diagnosis and to screen potential drugs or therapies for MAN2A1/MAN2A2-CDG in the future. (By Dr. Sonal Mahajan, https://jmg.bmj.com/content/early/2022/11/10/jmg-2022-108821 )