Related Experiment Video
Updated: Aug 7, 2026

Genetic Analysis of Hereditary Transthyretin Ala97Ser Related Amyloidosis
Published on: June 9, 2018
Anomalous rapid electrophoretic mobility of DNA containing triplet repeats associated with human disease genes
P D Chastain1, E E Eichler, S Kang
1Department of Biochemistry and Biophysics, Texas A&M University, Houston 77030-3303, USA.
Abstract:
Eight human genetic diseases have been associated with the expansion of CTG or CGG triplet repeats. The molecular etiology behind expansion is unknown but may involve participation of an unusual DNA structure in replication, repair, or recombination. We show that DNA fragments containing CTG triplet repeats derived from the human myotonic dystrophy gene migrate up to 20% faster than expected in nondenaturing polyacrylamide gels, suggesting the presence of an unusual DNA helix structure within the CTG triplet repeats. The anomalous migration is dependent upon the number of triplet repeats, the length of the flanking DNA, and the percentage and temperature of the polyacrylamide. The effect could be reduced by the addition of actinomycin D. Applying a reptation model for electrophoresis, the results are consistent with a 20% increase in persistence length of the DNA. PCR products containing CTG or CGG repeats from the spinocerebellar ataxia type I gene (SCA1) or the fragile X FMR1 gene, respectively, also showed higher electrophoretic mobility. These are the first sequences of defined length for which a dramatic increase in mobility can be attributed to sequence-dependent structural elements in DNA.
More Related Videos
08:22A Robust Polymerase Chain Reaction-based Assay for Quantifying Cytosine-guanine-guanine Trinucleotide Repeats in Fragile X Mental Retardation-1 Gene
Published on: September 16, 2019
05:22Electrophoretic Analysis of Replication Through Structure-Prone DNA Repeats Within the SV40-Based Human Episome
Published on: September 13, 2024
Related Concept Videos
Karyotyping
Genome Copying Errors
Exon Recombination
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Comparing Copy Number Variations and SNPs
Copy number variations or CNVs are the structural variations that cover more than 1kb of DNA sequence. The single nucleotide polymorphism (SNP), on the other hand, is a single nucleotide change or a point mutation that is found in more than 1%...
Genome-wide Association Studies-GWAS
GWAS does not require the identification of the target gene involved in...
Huntington Disease l: Introduction