Penetrance for<unk>  is<unk> 00% for most alleles, so almost all individuals who have at least one copy of the mutated gene will eventually develop symptoms. At least one case has been reported where penetrance may have been incomplete in a woman with 44 glutamine repeats with histidine interruptions whose father had exhibited symptoms, but herself had not shown symptoms at the age of 66. Individuals with a low number of repeats, around 39 to 55, typically live past reproductive age and can pass on the disease to their children, while high repeats may express juvenile onset and fatality.
Spinocerebellar ataxia type 1
Spinocerebellar ataxia type 6
Spinocerebellar ataxia type-13
Autosomal recessive cerebellar ataxia type 1
Metachromatic leukodystrophy
Benign hereditary chorea
Stratton Parker syndrome
Friedreich's ataxia