The autosomal dominant spinocerebellar ataxias: emerging mechanistic themes suggest pervasive Purkinje cell vulnerability

Abstract

The spinocerebellar ataxias are a genetically heterogeneous group of disorders with clinically overlapping phenotypes arising from Purkinje cell degeneration, cerebellar atrophy and varying degrees of degeneration of other grey matter regions. For 22 of the 32 subtypes, a genetic cause has been identified. While recurring themes are emerging, there is no clear correlation between the clinical phenotype or penetrance, the type of genetic defect or the category of the disease mechanism, or the neuronal types involved beyond Purkinje cells. These phenomena suggest that cerebellar Purkinje cells may be a uniquely vulnerable neuronal cell type, more susceptible to a wider variety of genetic/cellular insults than most other neuron types.

Keywords: Cerebellar Ataxia; Cerebellar Degeneration; Cerebellar Disease; Genetics; Medicine.

Figure 1

Overview of the spinocerebellar ataxia (SCA) disease mechanisms. 1: Transcriptionopathies (SCA1, 2, 3, 6, 7, 17). 2: Non-coding repeat expansions/RNA toxicity (SCA8, 10, 12, 31 36). 3: Voltage-gated potassium channel dysfunction (SCA13, 19/22). 4: ITPR1 loss (SCA15/16). 5: β3-Spectrin dysfunction (SCA5). 6: Mitochondrial dysfunction (SCA28). 7: Individual protein dysfunction (SCA11, 14, 23, 26, 27, 35).