Genetic Diversity and Expanded Phenotypes in Dystonia: Insights From Large-Scale Exome Sequencing

Area of Science:

• Genetics
• Neurology
• Movement Disorders

Background:

• Dystonia is a prevalent movement disorder with significant genetic heterogeneity, where the underlying causes remain largely unknown for most patients.
• Understanding the complex interplay between clinical symptoms and genetic variations in dystonia is an ongoing challenge.

Purpose of the Study:

• To investigate the genetic underpinnings of isolated dystonia by performing exome sequencing on a large cohort of genetically unsolved patients.
• To identify novel genetic variants and genes associated with dystonia and assess their diagnostic utility.

Main Methods:

• Whole exome sequencing was performed on 1924 patients with genetically unsolved, primarily late-onset isolated dystonia.
• Rare variants in 406 known dystonia-associated genes were analyzed, with pathogenic/likely pathogenic variants confirmed by Sanger sequencing.

Main Results:

• Likely pathogenic/pathogenic variants in 51 genes were identified in 8.1% of patients, with generalized dystonia and early onset (<30 years) being strong predictors of diagnosis.
• 56.2% of identified variants were novel, with recurrent variants found in EIF2AK2, VPS16, KCNMA1, and SLC2A1.
• Variants of uncertain significance were found in 16.9% of patients, and several genes not previously strongly linked to dystonia were implicated.

Conclusions:

• Exome sequencing is a valuable tool for diagnosing dystonia, revealing a complex genetic landscape with numerous implicated genes.
• The study substantiates several candidate genes for dystonia and broadens the known phenotypic spectrum associated with certain genetic variants.