PRORP and Perrault syndrome: Most of the other causes of Perrault syndrome are due to mutant genes that encode components of the mitochondrial RNA processing or translation pathway, such as the nucleoid replication/repair factor TWNK, the RNA degradation factor PRORP, the tRNA–amino acid synthases HARS2 and LARS2, and the mitoribosomal factor RMND1 [48,49].