ATN1 Repeat Expansion Testing

Description

Pathogenic CAG repeat expansions in the ATN1 gene have been associated with autosomal dominant dentatorubral-pallidoluysian atrophy (DRPLA). The pathogenic repeat expansions lead to expanded polyglutamine tracts that appear to form toxic neuronal intranuclear aggregates.

Pathogenicity is dependent upon CAG repeat length according to the following ranges 1-2:

Normal Alleles

Mutable Normal Alleles

Intermediate or Uncertain Alleles

Reduced Penetrance Alleles

Full Penetrance Alleles

6-35

-

-

36-47*

48 or more**

*Individuals with incompletely penetrant alleles may develop a mild form of DRPLA.

**Repeats 48 or longer are associated with adult onset. Repeats 63 or longer are associated with childhood onset.