C9orf72 and amyotrophic lateral sclerosis: Between 1% and 7% of patients with HD-like features do not actually carry an expansion of the HTT CAG repeat, but may in fact be affected by other HD-like syndromes such as HD-Like (HDL) 1, 2, 3, the spinocerebellar ataxias (SCAs), Friedreich ataxia (FRDA), and dentatorubral-pallidoluysian atrophy (DRPLA), and most commonly amyotropic lateral sclerosis (ALS or Lou-Gehrig’s disease) or frontotemporal lobar degeneration (FTLD) caused by expansions in the C9orf72 hexanucleotide repeat [20–26].