Recessive mutations cause a severe form of ataxia, Spinocerebellar Ataxia Autosomal Recessive 1 (SCAR1– OMIM: 606002), which is also known as Ataxia with Oculomotor Apraxia 2 (AOA2); while dominant mutations cause a motor neuron disease known as amyotrophic lateral sclerosis type 4 (ALS4; OMIM: 608465) [1], [2]. Here, SETX is linked to amyotrophic lateral sclerosis type 4.