Spinocerebellar ataxia type 21 (TMEM240) with tremor and dystonia.

We congratulate Riso et al. [1] for their excellent recent publication entitled "A NGS-based analysis on a large cohort of ataxic patients refines the clinical spectrum associated with SCA21", in which they present four new families with SCA21 of Italian and Libyan origin discussing the wide phenotypic diversity of this disease.