FGF14 and cerebellar ataxia: Overall, most patients with FGF14 expansion ≥ 250 AAG repeats (33/42; 78.5%) had a highly recognizable phenotype, characterized by the association of slowly progressive cerebellar signs accompanied by episodic symptoms of ataxia and/or downbeat nystagmus (DBN) that often present as first symptoms (Table 1, Supplementary Data 5).