Related Experiment Video
Updated: Jul 7, 2026
07:08
Fractionation for Resolution of Soluble and Insoluble Huntingtin Species
Published on: February 27, 2018
Huntington's disease as caused by 34 CAG repeats
Jürgen Andrich1, Larissa Arning, Stefan Wieczorek
1Department of Neurology, St. Josef Hospital Bochum, Ruhr-University Bochum, Gudrunstr. 56, Bochum, Germany.
Summary
Huntington's disease (HD) is a neurodegenerative disorder linked to expanded CAG repeats in the HD gene. This case study details a 75-year-old male exhibiting HD symptoms with 34 CAG repeats, an intermediate allele size.
Area of Science:
- Genetics
- Neurodegenerative Disorders
- Molecular Biology
Background:
- Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder.
- It results from expanded CAG (cytosine-adenine-guanine) trinucleotide repeats in the HD gene.
- Alleles with over 35 CAG repeats typically manifest clinical HD.
Observation:
- This report focuses on a 75-year-old male patient.
- The patient presented with clinical symptoms consistent with Huntington's disease.
- Genetic analysis revealed 34 CAG repeat units in the HD gene.
Findings:
- The patient's 34 CAG repeat count falls within the intermediate range (27-35 repeats).
- Intermediate alleles are associated with an increased risk of expansion in future generations.
- This case highlights the potential for clinical manifestation even with borderline repeat numbers.
Implications:
- This case underscores the complex genotype-phenotype correlations in Huntington's disease.
- Understanding intermediate alleles is crucial for genetic counseling and risk assessment.
- Further research into the mechanisms of repeat expansion and clinical presentation is warranted.
Related Concept Videos
01:21Huntington Disease l: Introduction
Huntington disease or HD is a progressive, fatal neurodegenerative disorder inherited in an autosomal dominant pattern.PathophysiologyIt is caused by expansion of the CAG trinucleotide repeat in the HTT gene on chromosome 4 (4p16.3), producing an abnormal huntingtin protein with an expanded polyglutamine tract. This misfolded protein disrupts cellular function, leading to neuronal death. Normal alleles have ≤26 repeats, 27–35 are intermediate (risk of expansion), 36–39 show reduced penetrance,...
01:11Genetic Lingo
Overview
01:23Alzheimer Disease ll: Pathophysiology
Alzheimer disease involves structural changes in the brain that begin long before symptoms appear. The most distinctive features are extracellular neuritic plaques and intracellular neurofibrillary tangles.Neuritic plaques form in the cerebral cortex and around blood vessels. These plaques contain a dense core of beta-amyloid (Aβ)—a toxic protein fragment that clumps outside neurons. The core is surrounded by damaged neuronal extensions, as well as reactive astrocytes and microglia. Abnormal...
01:29Alzheimer Disease l: Introduction
Alzheimer disease is a chronic, progressive, and irreversible neurodegenerative disorder and the most common cause of dementia in older adults. It leads to gradual neuronal loss, causing cognitive decline, behavioral changes, and loss of functional independence.Risk Factors and EtiologyThe disease is multifactorial. Age is the strongest risk factor, with prevalence doubling every 5 years after age 65. Genetic factors include mutations in genes such as APP, PSEN1, and PSEN2, which are associated...
01:29Cardiomyopathy III: Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy, or HCM, is an autosomal dominant genetic disorder characterized by asymmetric left ventricular hypertrophy without ventricular dilation. It is more common in men and is typically diagnosed in young, athletic adults.EtiologyHCM is primarily genetic and is caused by mutations in genes encoding sarcomeric proteins. Researchers have identified over 1400 mutations across at least 11 different genes. Among these, the most frequently occurring mutations are found in the...
01:31Translation
Lesson: Translation
Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes the final step in the expression of genes. This process is carried out by ribosomes, complexes of protein and specialized RNA molecules. Ribosomes, transfer RNA (tRNA), and other proteins produce a chain of amino acids—the polypeptide—as the end product of translation.
Translation Produces the Building Blocks of Life
Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes the final step in the expression of genes. This process is carried out by ribosomes, complexes of protein and specialized RNA molecules. Ribosomes, transfer RNA (tRNA), and other proteins produce a chain of amino acids—the polypeptide—as the end product of translation.
Translation Produces the Building Blocks of Life