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Purpose: In Huntington disease (HD), synonymous variants causing loss or duplication of the interrupting CAA codon in the CAG repeat modify disease onset. These variants are undetectable during HD genetic testing, resulting in inaccurate diagnostic reporting of uninterrupted CAG repeat length. Inaccurate reporting of CAG repeat length results in misdiagnosis of individuals with alleles near diagnostic cut-offs. We present a method to identify variant alleles during CAG repeat genotyping, allowing accurate diagnostic reporting of uninterrupted CAG repeat length.
Methods: We used triplet-primed PCR (TP-PCR) to amplify CAG repeat alleles with canonical or noncanonical repeat interruptions and leveraged differences in peak amplification patterns to develop a screening method based on peak height ratio (PHR). We used PHR to screen blood DNA from a cohort of symptomatic individuals with diagnostic CAG repeat lengths of 40 to 41.
Results: TP-PCR enables accurate reporting of uninterrupted CAG repeat length in diagnostic testing by detecting HD alleles with loss or duplication of the CAG repeat interruption.
Conclusion: PHR screening of TP-PCR traces is a cost-effective screening method for detection, ascertainment of uninterrupted CAG repeat length, and accurate diagnostic reporting for individuals with disease-modifying noncanonical CAG repeat interruptions.
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http://dx.doi.org/10.1016/j.gimo.2024.101882 | DOI Listing |
Brain Commun
August 2025
Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129, USA.
was identified in human and mouse Huntington's disease brain as the pathogenic exon 1 mRNA generated from aberrant splicing between exon 1 and 2 of that contributes to aggregate formation and neuronal dysfunction. Detection of the huntingtin exon 1 protein (HTT1a) has been accomplished with Meso Scale Discovery, Homogeneous Time Resolved Fluorescence and immunoprecipitation assays in Huntington's disease knock-in mice, but direct detection in homogenates by gel electrophoresis and western blot assay has been lacking. Subcellular fractions prepared from mouse and human Huntington's disease brain were separated by gel electrophoresis and probed by western blot with neoepitope monoclonal antibodies 1B12 and 11G2 directed to the C-terminal eight residues of HTT1a.
View Article and Find Full Text PDFParkinsonism Relat Disord
September 2025
Federal University of São Paulo, Department of Neurology and Neurosurgery, São Paulo, SP, Brazil.
Background: Huntington disease-like 2 (HDL2) is an autosomal dominant disorder caused by an abnormal CAG/CTG repeat in exon 2A of junctophilin-3. This is the most common Huntington's Disease phenocopy and is characterized by psychiatric, cognitive, and movement disorders. This study aimed to describe the clinical phenotype of HDL2 patients in Brazil and compare the findings with those in the literature.
View Article and Find Full Text PDFNeurogenetics
September 2025
Nur International University, 54600, Lahore, Punjab, Pakistan.
Huntington's disease (HD) is a progressive, autosomal dominant neurodegenerative disorder characterized by motor dysfunction, cognitive decline, and psychiatric disturbances. It is caused by CAG repeat expansions in the HTT gene, resulting in the formation of mutant huntingtin protein that aggregates and disrupts neuronal function. This review outlines the pathogenesis of HD, including genetic, molecular, and environmental factors.
View Article and Find Full Text PDFNeurotherapeutics
September 2025
Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA. Electronic address:
Spinal and bulbar muscular atrophy (SBMA) is a CAG/polyglutamine (polyQ) repeat expansion disorder in which the mutant androgen receptor (AR) protein triggers progressive degeneration of the neuromuscular system in men. As the misfolded polyQ AR is the proximal mediator of toxicity, therapeutic efforts have focused on targeting the mutant protein, but these prior efforts have met with limited success in SBMA patients. Here, we examine the efficacy of small molecule AR proteolysis-targeting chimera (PROTAC) degraders that rapidly and potently promote AR ubiquitination and degradation by the proteasome.
View Article and Find Full Text PDFFront Neurol
August 2025
Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.
Background: Pediatric Huntington's disease (PHD), a rare and severe form of juvenile-onset Huntington's disease (JOHD), is associated with highly expanded CAG repeats in the gene and a rapidly progressive neurodegenerative course. Recent studies have suggested that glucose metabolism may be impaired in PHD due to reduced expression of glucose transporters in the brain, resembling aspects of GLUT1 Deficiency Syndrome (GLUT1DS).
Methods: We investigated glucose metabolism in two pediatric patients with genetically confirmed PHD (CAG repeats: 76 and 79) referred to our tertiary care center.