PTPRQ and External ophthalmoplegia: Two SCAR8 patients (cases 8 and 10) both had symptoms of pure cerebellar ataxia, while the hearing loss of case 10 was caused by mutations in PTPRQ. Moreover, the remaining three patients exhibited variable additional extracerebellar neurological symptoms (peripheral polyneuropathy, mental retardation, dizziness, pes cavus, external ophthalmoplegia, myoclonic jerks) and non-neurologic dysfunctions (psychiatric symptoms).