The volume loss can be correlated to severity and duration.An estimated 77% of cases of progressive cerebellar disease are reported to have one or more mental health disorders, and 19% exhibit cognitive disorders. These estimates are consistently higher than the portion with mental health disorders in the general population, but still follow other general patterns, like correlations between depression frequency and sex or age. It is unclear if depression can be linked causally to cerebellar degeneration; one study reports data consistent with depression primarily being a response to the disability, not a symptom of it, while another reports evidence that depression may have a causal link; prevalence of depression varies differently between SCA types than does the rate of progression of disability. Genetics
Spinocerebellar ataxia type 1 is caused by a mutation in the ATXN1 gene. This mutation is passed down through an autosomal dominant inheritance pattern, meaning that the disease does not skip generations, at least one parent must have the disease for the children to inherit it, and that the odds of any given child inheriting SCA 1, regardless of gender or other phenotypes, is 50% if the affected parent is heterozygous. : 26  The ATXN1 gene on chromosome 6 encodes the ataxin 1 protein, which is used in signaling pathways and gene regulation, and is heavily expressed in Purkinje neurons. The coding region for Ataxin 1 (6p22.3) contains a polyglutamine tract of variable length.
The autosomal recessive inheritance in Fryns syndrome contrasts with the sporadic inheritance for most patients with DIH. References


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