STRs database » CACNA1A locus

Overview of repeats

The normal length of repeats for the CACNA1A gene is usually between 4 and 16 repeats (Zhuchenko et al. (1997)), but a healthy individual carrying 18 repeats in the allele have been found as well (Riess (1997)). An affected individual being homozygous for an intermediate allele of 19 repeats has been described in Italian family (Mariotti et al. (2001)). The pathogenic range starts from 21 repeats of CAG which is known to cause spinocerebellar ataxia type 6 (Riess (1997)).

In an observational study of 2768 individuals undergoing SCA6 testing, Hatano et al. (2025) described 19-20 repeats as an intermediate zone and found that the opposite allele influenced age at onset in individuals with 21-22 repeats. The authors reported that at least 23 repeats were associated with onset within a typical lifespan independently of the opposite allele in their cohort.

→ View STRipy's population-wide repeat data for CACNA1A locus