Symptoms of cerebellar ataxia
Predictive diagnostics in persons at risk in affected families
Prenatal diagnostics in known carriers.
Spinocerebellar Ataxia Type 6, SCA 6 - CACNA1A
Spinocerebellar ataxia type 6, SCA 6
Clinical Features
Spinocerebellar ataxias of different types show similar clinical features and are therefore not or hardly distinguishable on clinical grounds. The SCAs typically manifest in adulthood and are clinically characterized by cerebellar gait and limb ataxia, dysarthria and oculomotor disturbances, muscular hypotonia, dysdiadochokinesia, intentional tremor, and extrapyramidal symptoms. Pyramidal signs, participation of the peripheral nervous system (polyneuropathy) and autonomous systems (imperative micturition, impotence, orthostatic dysregulation) may occur (see also Information on SCA1 and SCA3).
Genetic Information
The SCA subtype 6 (chromosome 19p13, gene CACNA1A) is autosomal dominant inherited and caused by expanded CAG repeats of the SCA gene locus.
Disease onset and phenotype are variable and do not correlate with increasing repeat.. In SCA6, transmission of repeats through the male or female germline is stable.
| Repeats | |
| normal allele | < 19 |
| pathological allele, reduced penetrance, meiotic unstable |
19 |
| pathological allele |
20 - 33 |
Diagnostic
Indication
Method
Normal and expanded CAG repeats are detected by PCR and subsequent fragment length analysis.
Sample Requirement
2 - 4 ml of EDTA blood
Duration
approx. 2 weeks