# Exome Sequence Analysis to Characterize Undiagnosed Family Segregating Motor Impairment and Dystonia

## TL;DR

Researchers used exome sequencing to identify a genetic variant causing motor impairment and dystonia in a Saudi family, expanding the known mutations in the SLC30A10 gene.

## Contribution

The study identifies a novel pathogenic variant in SLC30A10 and expands its mutation spectrum in a distinct population.

## Key findings

- A homozygous missense variant (c.266T>C; p.L89P) in the SLC30A10 gene was identified as the cause of the disease.
- The variant was validated through Sanger sequencing and predicted to be pathogenic using bioinformatics tools.
- The variant is highly conserved in vertebrates, supporting its clinical significance.

## Abstract

Background: Hypermanganesemia with dystonia 1 (HMNDYT1) is a rare genetic disorder characterized by elevated blood manganese levels. This condition is associated with polycythemia, motor neurodegeneration with extrapyramidal features, and hepatic dysfunction, which can progress to cirrhosis in some patients. Materials and Methods: In this study, a consanguineous Saudi family with two affected individuals exhibiting symptoms of severe motor impairment, spastic paraparesis, postural instability, and dystonia was studied. Clinical and radiographic evaluations were conducted on the affected individuals. Whole exome sequencing (WES) was performed to diagnose the disease and to determine the causative variant underlying the phenotype. Moreover, Sanger sequencing was used for validation and segregation analysis of the identified variant. Bioinformatics tools were utilized to predict the pathogenicity of candidate variants based on ACMG criteria. Results: Exome sequencing detected a recurrent homozygous missense variant (c.266T>C; p.L89P) in exon 1 of the SLC30A10 gene. Sanger sequencing was employed to validate the segregation of the discovered variant in all available family members. Bioinformatics tools predicted that the variant is potentially pathogenic. Moreover, conservation analysis showed that the variant is highly conserved in vertebrates. Conclusions: This study shows that exome sequencing is instrumental in diagnosing undiagnosed neurodevelopmental disorders. Moreover, this study expands the mutation spectrum of SLC30A10 in distinct populations.