Decreasing expression of COX5B will lead to a failure in complex IV assembly [40], subsequently causing brain mitochondria dysfunction which has been reported to be associated with some neurodegenerative disorders of the central nervous system, such as multiple sclerosis (MS) [41–44], spinobulbar muscular atrophy (SBMA) [45], Alzheimer’s disease (AD) [46–48] and Parkinson’s disease (PD) [49,50]. Here, COX5B is linked to early-onset autosomal dominant Alzheimer disease.