GJA1 and early-onset autosomal dominant Alzheimer disease: To gain insight into the role of GJA1 in cognitive functions and AD pathogenesis, we first extensively investigated how GJA1 expression at the mRNA level was correlated with AD neuropathological traits in 29 gene expression datasets from three AD cohort studies of aging and dementia that included organ donation at death: the Mount Sinai/JJ Peters VA Medical Center Brain Bank (MSBB; Additional file 1: Table S1) [91], the Religious Orders Study and the Rush Memory and Aging Project (ROSMAP) [8, 9] and in the Harvard Brain Tissue Resource Center Alzheimer’s Disease study (HBTRC) [98].