Huntingtin protein co-localizes with ATM repair protein at sites of DNA damage.  Huntingtin is a scaffolding protein in the ATM oxidative DNA damage response complex.  Huntingtons disease patients with aberrant huntingtin protein are deficient in repair of oxidative DNA damage.  Oxidative DNA damage appears to underlie Huntingtons disease pathogenesis.   Huntington's disease is likely caused by the dysfunction of mutant huntingtin scaffold protein in DNA repair leading to increased oxidative DNA damage in metabolically active cells.