POLG and spinocerebellar ataxia with epilepsy: ACAD9, CPEO, Leigh syndrome, LHON, FRDA, MELAS, MERRF, Methylmalonic aciduria, MIDD, MLASA, MNGIE, NARP, NDFUF2, NDUFV2, NDUFAF1, PEO, Sengers Syndrome, TMEM70 deficiency, SANDO, SCAE