Related Experiment Video
Updated: Jul 16, 2026
09:06
Whole-brain Segmentation and Change-point Analysis of Anatomical Brain MRI—Application in Premanifest Huntington's Disease
Published on: June 9, 2018
Reduced penetrance alleles for Huntington's disease: a multi-centre direct observational study
Journal of Medical Genetics
|March 16, 2007
Summary
Huntington's disease penetrance is at least 40% at age 65 and 30% at age 75 for individuals with 36-39 CAG repeats. This study assessed DNA reporting consistency between two centers.
Area of Science:
- Genetics
- Neurology
Background:
- Huntington's disease (HD) is a progressive neurodegenerative disorder caused by an expansion of CAG repeats in the HTT gene.
- Individuals with 36-39 CAG repeats represent a gray zone for predicting disease onset and penetrance.
Discussion:
- This study evaluated the penetrance of Huntington's disease in individuals with 36-39 CAG repeats.
- It also assessed the consistency of reporting the upper allele from two reference DNA testing centers.
Key Insights:
- Penetrance figures for this cohort at age 65 and 75 years were 63.9% and 74.2%, respectively.
- A conservative estimate suggests at least a 40% chance of remaining asymptomatic at age 65 and a 30% chance at age 75.
- Minor discrepancies (4.2%) in CAG repeat reporting were observed between centers, with a 0.84% discrepancy between 39 and 40 repeats.
Outlook:
- Further research can refine penetrance predictions for intermediate CAG repeat ranges.
- Standardization of DNA testing protocols can improve reporting consistency for Huntington's disease genetic testing.
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
01:11Genome-wide Association Studies-GWAS
Genome-wide association studies or GWAS are used to identify whether common SNPs are associated with certain diseases. Suppose specific SNPs are more frequently observed in individuals with a particular disease than those without the disease. In that case, those SNPs are said to be associated with the disease. Chi-square analysis is performed to check the probability of the allele likely to be associated with the disease.
GWAS does not require the identification of the target gene involved in...
GWAS does not require the identification of the target gene involved in...