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 complex genetic underpinnings.
• Existing genetic knowledge explains only a fraction of dystonia cases.
• Understanding genotype-phenotype correlations in dystonia remains challenging.

Purpose of the Study:

• To comprehensively analyze the genetic spectrum of dystonia using exome sequencing.
• To identify novel pathogenic variants and implicated genes in a large cohort of unsolved dystonia patients.
• To correlate genetic findings with clinical manifestations, including age at onset and dystonia type.

Main Methods:

• Whole exome sequencing was performed on 1,924 dystonia patients, including 1,895 genetically unsolved index patients.
• Rare variants in known and novel dystonia-associated genes were analyzed.
• Variants were confirmed by Sanger sequencing, and segregation analysis was conducted where possible.
• Functional evidence supported novel variant types, and de novo occurrences were noted.

Main Results:

• Identified 137 likely pathogenic/pathogenic variants in 51 genes in 163 patients, yielding an 8.1% diagnostic rate.
• 77 (56.2%) of identified variants were novel, with recurrent variants in EIF2AK2, VPS16, KCNMA1, and SLC2A1.
• VPS16, THAP1, GCH1, SGCE, GNAL, and KMT2B were among the most frequently implicated genes.
• Early age at onset (<30 years) and generalized dystonia significantly increased the likelihood of a genetic diagnosis.

Conclusions:

• Exome sequencing is a valuable tool for diagnosing genetically heterogeneous dystonia.
• The study expands the list of dystonia-associated genes and their phenotypic spectrum.
• Findings provide critical insights into the genetic architecture of dystonia, aiding future research and clinical practice.