The human hippocampus is a unique cortical structure central to brain function, plasticity, and disease. Unravelling its complex organization requires the integration of multiscale data, linking molecular features to mesoscale anatomy and macroscale functional patterns. Gene expression is a fundamental microscale phenotype, and its profiling can provide a reference description of how molecular features are distributed across the brain. Capitalizing on recent imaging-transcriptomic analyses, we introduce HippoGenes, a repository of fine-grained gene expression patterns across human hippocampal subregions. We leveraged spatial statistical models and hippocampal surface mapping to reconstruct dense transcriptomic maps from sparse post-mortem tissue samples of the Allen Human Brain Atlas, generating continuous expression estimates for thousands of genes aligned to a common surface-based coordinate system. We illustrate the utility of HippoGenes to (i) map medial-lateral and anterior-posterior transcriptomic gradients that align with subfield and tripartite subdivisions of the hippocampal formation, (ii) examine associations between gene expression and canonical microstructural and functional features of the hippocampus, and (iii) perform a molecular decoding of subregional alterations in neurological patients with hippocampal pathology. HippoGenes provides a framework for exploring the molecular organization of the hippocampus, opening avenues for multiscale integration in health and disease, and is openly available on https://hippogenes.readthedocs.io/.
A. Ngo, Sara Larivière, J. Royer et al.· bioRxiv· 0 citations
BackgroundThe SLC25A46 gene encodes a mitochondrial carrier protein previously implicated in neuropathy and optic atrophy. Biallelic variants in SLC25A46 have been described in patients with Parkinson's disease (PD) with optic atrophy, but the evidence supporting a role in PD remains limited.ObjectiveTo assess whether SLC25A46 variants contribute to PD, REM sleep behavior disorder (RBD), or dementia with Lewy bodies (DLB).MethodsWe examined common variants using four representative PD genome-wide association studies (GWAS) and an RBD GWAS and applied summary-data-based Mendelian randomization (SMR) to evaluate whether genetically regulated expression of SLC25A46 shows a causal association with the risk of PD or RBD. Rare variant analyses were conducted in four cohorts of European descent: Accelerating Medicines Partnership: Parkinson's Disease (AMP-PD) PD (3,051 PD, 3,667 controls), UK Biobank (3,267 PD, 14,939 proxy, 54,800 controls), RBD (1,376 RBD, 2,580 controls), and AMP-PD DLB (2,605 DLB, 1,894 controls). Optimal sequence kernel association test (SKAT-O) and meta-analysis were used to assess rare variants.ResultsNo associations were observed between SLC25A46 variants and PD, RBD, or DLB. SMR analyses revealed no evidence supporting a causal relationship between SLC25A46 expression and PD or RBD risk. Rare variant burden analyses did not identify significant associations after multiple-testing correction across cohorts or meta-analyses.ConclusionSLC25A46 variants showed no evidence of association, suggesting the gene does not play a major role in PD, RBD, or DLB risk.
Han Yu, S. C. Parlar, K. Senkevich et al.· Journal of Parkinson's Disea...· 0 citations