DMPK Repeat Expansion Testing

Description

Pathogenic CTG repeat expansions within the 3′ untranslated region of the DMPK gene have been associated with autosomal dominant myotonic dystrophy type 1 (DM1). The pathogenic repeat expansions are thought to cause abnormal RNA processing, which may impact the splicing of multiple genes.

Pathogenicity is dependent upon CTG repeat length according to the following ranges 1-3:

Normal Alleles

Mutable Normal Alleles

Pathogenic Mild Late Onset

Pathogenic Classic

Pathogenic Congenital Onset

5-34

35-49*

50-150

100-1000

1001 or more

*Mutable normal alleles may expand or contract in subsequent generations.

Tests That Analyze DMPK Repeats