STRs database » ATXN8OS locus

Overview of repeats

ATXN8OS is the opposite strand of the ATXN8 gene that produces a repeat-containing transcript that is associated with the spinocerebellar ataxia type 8 (SCA8) (Daughters et al. (2009)). Bidirectional transcription at this locus produces an ATXN8OS repeat-containing RNA and an ATXN8 polyglutamine product, both implicated in disease (Daughters et al. (2009)).
The cut-off values for pathogenic length of repeats is debatable as many studies have shown the pathogenic range to be above 80 repeats, whereas one of the biggest ones so far has reported that intermediate alleles (45-109 CTGs) were found in almost similar frequencies in both controls and patients (Schöls et al. (2003)). However, there are also reports of many healthy individuals who had a repeat length over 91 CTGs (Zeman et al. (2004)). This shows the overlap in repeat length of individuals with and without SCA8 and it is recommended to interpret genotyping results in clinical context (Gupta & Jankovic (2009)). In general, the majority of studies show a repeat length at least 80 for affected individuals but at least 50 should be expected for a SCA8 patient (Gupta & Jankovic (2009)). In over 99% healthy controls the range has been shown to be between 2 and 37 repeats (Brusco et al. (2002)). Based on the studies, we have specified here an intermediate range between 38-79.

In a study of SCA8 families, Perez et al. (2021) found CCG/CGG interruptions associated with higher disease penetrance. Their cellular experiments showed increased RAN-translation products and toxicity from interrupted repeat constructs compared with pure repeats.

→ View STRipy's population-wide repeat data for ATXN8OS locus