Initially, the identification of mutations in the tRNA splicing endonuclease (TSEN) complex led researchers to a hypothesis that mutations in genes involved in tRNA processing (CLP1, RARS2, SEPSECS, TSEN2, TSEN15, TSEN34, TSEN54) play a role in PCH etiology. The gene discussed is TSEN34; the disease is pontocerebellar hypoplasia.