For example, the lethal heterogeneous neurodegenerative disease pontocerebellar hypoplasia (PCH6) was linked to the RARS2 (mitochondrial arginyl-tRNA synthetase) gene in a patient with a homozygous frameshift mutation predicted to generate a truncated protein (Edvardson et al., 2007). This evidence concerns the gene RARS2 and pontocerebellar hypoplasia.