Background: Trinucleotide repeat expansions are an emerging class of genetic variants associated with various movement disorders. Unbiased genome-wide analyses can reveal novel genotype-phenotype associations and provide a diagnosis for patients and families.
Objective: The aim was to identify the genetic cause of a severe progressive movement disorder phenotype in 2 affected brothers.
Methods: A family of 2 affected brothers and unaffected parents had extensive phenotyping since birth. Whole-genome and long-read sequencing methods characterized genetic variants and methylation status.
Results: Two male siblings with a CGG repeat expansion in the 5'-untranslated region (UTR) of disco-interacting protein 2 homolog B (DIP2B) presented with a novel DIP2B phenotype, including neurodevelopmental disability, dysmorphic traits, and a severe progressive movement disorder (chorea, dystonia, and ataxia).
Conclusions: This is the first report of a severe progressive movement disorder phenotype associated with a CGG repeat expansion in the DIP2B 5'-UTR. © 2025 International Parkinson and Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
Background: Mitochondrial dysfunction is increasingly recognized as a key factor in neurodegenerative diseases (NDDs), underscoring the therapeutic potential of targeting mitochondria-related genes. This study aimed to identify novel biomarkers and drug targets for these diseases through a comprehensive analysis that integrated genome-wide Mendelian randomization (MR) with genes associated with mitochondrial function.
Methods: Using existing publicly available genome-wide association studies (GWAS) summary statistics and comprehensive data on 1136 mitochondria-related genes, we initially identified a subset of genes related to mitochondrial function that exhibited significant associations with NDDs. We then conducted colocalization and summary-data-based Mendelian randomization (SMR) analyses using expression quantitative trait loci (eQTL) to validate the causal role of these candidate genes. Additionally, we assessed the druggability of the encoded proteins to prioritize potential therapeutic targets for further exploration.
Results: Genetically predicted levels of 10 genes were found to be significantly associated with the risk of NDDs. Elevated DMPK and LACTB2 levels were associated with increased Alzheimer's disease risk. Higher expression of NDUFAF2, BCKDK, and MALSU1, along with lower TTC19, raised Parkinson's disease risk. Higher ACLY levels were associated with both amyotrophic lateral sclerosis and multiple sclerosis (MS) risks, while decreased MCL1, TOP3A, and VWA8 levels raised MS risk. These genes primarily impact mitochondrial function and energy metabolism. Notably, several druggable protein targets identified are being explored for potential NDDs treatment.
Conclusions: This data-driven MR study demonstrated the causal role of mitochondrial dysfunction in NDDs. Additionally, this study identified candidate genes that could serve as potential pharmacological targets for the prevention and treatment of NDDs. © 2025 International Parkinson and Movement Disorder Society.