CSTB Repeat Expansion Testing
Description
Pathogenic dodecamer CCCCGCCCCGCG repeat expansions in the CSTB gene have been associated with autosomal recessive progressive myoclonic epilepsy type 1 (EPM1), also known as Unverricht-Lundborg disease. Biallelic pathogenic variants, including dodecamer repeat expansions, lead to the loss of CSTB function and abnormal proteolytic activity.
Pathogenicity is dependent upon CCCCGCCCCGCG repeat length according to the following ranges 1-3:
Normal Alleles | Mutable Normal Alleles | Intermediate or Uncertain Alleles | Reduced Penetrance Alleles | Full Penetrance Alleles |
12 or fewer | - | 13-29 | - | 30 or more |