**3.3 Inherited ataxia**

The vast set of clinically and genetically diverse, complicated neurodegenerative disorders known as inherited cerebellar ataxias is brought on by several genetic

### **Figure 1.** *T2-weighted, axial image of a brain MRI in a patient presenting Joubert's syndrome and the molar tooth sign [23].*

abnormalities. There are two X-linked ataxias, more than 30 ARCAs, almost 40 SCA forms, and several mitochondrial ataxias among the hereditary cerebellar ataxias [24, 25, 31, 34].
