MT-RNR2 and Alzheimer disease: A close homolog of human MT-RNR2, the humanin-like protein 8 (MTRNR2L8), which differs from MT-RNR2 only by a single residue and which has a polymorphism that causes it to be identical to MT-RNR2 [95], was previously found to display significantly increased expression in excitatory neurons with AD pathology vs. no pathology in prefrontal cortex samples from human subjects (q value = 2.9E-182; this result derived from single-nucleus RNA-seq data was also confirmed by qPCR by the authors) [9].