MGMT and Friedreich ataxia: In mammalian cells, at least nine distinct pathways are involved for the repair of different genotoxic lesions: mismatch repair (MMR), base excision repair (BER), nucleotide excision repair (NER), translesion synthesis (TLS), homologous recombination (HR), non-homologous end joining (NHEJ), alternative end joining (alt-EJ), Fanconi anemia (FA), and O6-methylguanine DNA methyltransferase (MGMT).