The first patients described with mutations in RARS2, the gene encoding for the mitochondrial arginyl-tRNA synthetase (mt-ArgRS), presented progressive atrophy in cerebellum, pons (pontocerebellar hypoplasia type 6, PCH6; OMIM#611523), with cerebral cortex and white matter involvement, causing a severe infantile clinical picture characterized by lethargy, seizures with apneic spells, hypotonia, and premature death. The gene discussed is RARS2; the disease is pontocerebellar hypoplasia type 6.