bioRxiv. 2025 Jun 03. pii: 2025.06.01.657261. [Epub ahead of print]
Andrew C Edmondson,
Rohit Budhraja,
Zijie Xia,
Ashley Melendez-Perez,
Cadmus Cai,
Silvia Radenkovic,
Ashley M Collins,
Emily J Shiplett,
Sophie F Hill,
Ala Somarowthu,
Johanna Dam,
Ling-Lin Pai,
Mariarita Santi,
Seonhee Kim,
Miao He,
Ethan M Goldberg,
Tamas Kozicz,
Eva Morava,
Akhilesh Pandey,
Zhaolan Zhou.
Congenital disorders of glycosylation (CDG) are a group of neurogenetic conditions resulting from disruptions in the cellular glycosylation machinery. The majority of CDG patients have compound heterozygous pathogenic variants in the phosphomannomutase 2 ( PMM2) gene. Individuals with PMM2-CDG exhibit multi-systemic symptoms, prominently featuring neurological deficits with nearly all patients exhibiting cerebellar hypoplasia and ataxia. To overcome embryonic lethality caused by whole body knock-out of Pmm2 and mimic patient-related compound heterozygous pathogenic variants, we paired a Pmm2 flox allele ( Pmm2 fl ) with a catalytically inactive knock-in allele ( Pmm2 R137H ), commonly present in PMM2-CDG patients. Mice with post-mitotic loss of PMM2 from neurons or astrocytes are indistinguishable from unaffected littermates, including in a broad battery of neurological assessments. In contrast, removal of PMM2 from embryonic neural precursor cells leads to cerebellar hypoplasia, ataxia, seizures, and early lethality. Comprehensive multi-omics profiling, including metabolomics, glycomics, single-cell transcriptomics, proteomics, and glycoproteomics, reveal widespread molecular disturbances throughout the brain, with the cerebellum showing the most pronounced disruption. These findings highlight the heightened dependency of the developing cerebellum on intact N-glycosylation, aligning with clinical observations in PMM2-CDG patients. Importantly, glycoproteomic alterations identified in our mouse model are corroborated in PMM2-CDG patient post-mortem cerebellar tissue, underscoring the translational relevance of our findings and implicating impaired synaptic transmission as a key pathogenic mechanism.