The PMPCB gene encodes for the catalytic subunit of the essential mitochondrial processing protease (MPP), and the bi-allelic loss-of-function has been shown to cause multiple mitochondrial dysfunctions syndrome-6 (MMDS6), a severe and early-onset neurodegenerative disorder (Vogtle et al., 2018). The gene discussed is PMPCB; the disease is multiple mitochondrial dysfunctions syndrome 6.