Additional screening of 21 Tunisian individuals, suffering from cerebellar ataxia of unknown genetic cause, revealed a third mutation in exon 2 of the GBA2 gene in three siblings (c.363C>A), resulting in a truncated GBA2 protein Y121*, lacking both the C-terminal beta-glucosidase and the N-terminal domain (Figure 2). The gene discussed is GBA2; the disease is aceruloplasminemia.