GLUD2 and Alzheimer disease: Other differences include a human-specific de novo protein-coding gene, namely C20orf203, that is most abundantly expressed in brain, whose aberrant expression is involved in human-specific pathogenesis of Alzheimer’s disease (AD) [14], and GLUD2, a hominoid specific brain enzyme that contributes to human cognitive abilities but also appears to confer vulnerability to brain tumors [15].