Huntington’s disease as an autosomal dominant inherited disease manifests after an unstable overreplication of cytosine, adenine and guanine, which encodes an abnormally long polyglutamine tract in the huntingtin protein, and the age at onset of HD is inversely related to the repetition of a number of cytosines, adenine and guanine (Borrell-Pagès et al., 2006; Ramaswamy et al., 2007; Gil and Rego, 2008; Imarisio et al., 2008). The gene discussed is HTT; the disease is Huntington disease.