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Related Concept Videos

Non-LTR Retrotransposons03:18

Non-LTR Retrotransposons

As the name suggests, non-LTR retrotransposons lack the long terminal repeats characteristic of the LTR retrotransposons. Additionally, both LTR and non-LTR retrotransposons use distinct mechanisms of mobilization. Non-LTR retrotransposons are further divided into two classes - Long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs), both of which occur abundantly in most mammals, including humans. Some of the active non-LTR retrotransposons in humans are L1...
Genome Copying Errors02:46

Genome Copying Errors

DNA replication is a well-evolved process that copies millions of base pairs with high fidelity during each cell division. Occasionally a wrong base or a long stretch of wrong bases may get added to the daughter strands. If the errors are left unchecked, cells might accumulate several mutations that might endanger their  survival. Therefore, the copying errors are checked and repaired at three levels.
Gene Duplication and Divergence02:37

Gene Duplication and Divergence

The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was  generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
Exon Recombination02:32

Exon Recombination

The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes. 
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Comparing Copy Number Variations and SNPs02:26

Comparing Copy Number Variations and SNPs

Sequencing of the human genome has opened up several best-kept secrets of the genome. Scientists have identified thousands of genome variations that exist within a population. These variations can be a single nucleotide or a larger chromosomal variation.
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-GWAS01:11

Genome-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...

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Related Experiment Video

Updated: May 10, 2026

Screening for Functional Non-coding Genetic Variants Using Electrophoretic Mobility Shift Assay (EMSA) and DNA-affinity Precipitation Assay (DAPA)
11:35

Screening for Functional Non-coding Genetic Variants Using Electrophoretic Mobility Shift Assay (EMSA) and DNA-affinity Precipitation Assay (DAPA)

Published on: August 21, 2016

Expandable DNA repeats and human disease.

Sergei M Mirkin1

  • 1Department of Biology, Tufts University, Medford, Massachusetts 02155, USA. sergei.mirkin@tufts.edu

Nature
|June 22, 2007
PubMed
Summary

Expanded DNA repeats cause nearly 30 hereditary disorders by disrupting cellular processes. These repeat expansions, often in non-coding gene regions, alter gene expression and drive disease pathogenesis through unusual transcript structures.

Area of Science:

  • Genetics and Molecular Biology
  • Human Hereditary Disorders
  • Genomic Instability

Background:

  • Approximately 30 human hereditary disorders are linked to expansions of simple repetitive DNA sequences.
  • These repetitive DNA sequences possess unusual structural characteristics that interfere with DNA replication, repair, and recombination.
  • Expanded DNA repeats can lead to altered gene expression in human cells, contributing to disease development.

Purpose of the Study:

  • To investigate the mechanisms by which expanded DNA repeats cause hereditary disorders.
  • To understand the role of unusual structural features of DNA repeats in genomic instability.
  • To elucidate how repeat expansions, particularly in non-coding gene regions, contribute to disease pathogenesis.

Main Methods:

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Last Updated: May 10, 2026

Screening for Functional Non-coding Genetic Variants Using Electrophoretic Mobility Shift Assay (EMSA) and DNA-affinity Precipitation Assay (DAPA)
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  • Analysis of genomic DNA structures in individuals with hereditary disorders.
  • Investigation of cellular replication, repair, and recombination machinery interactions with expanded repeats.
  • Study of gene expression alterations caused by expanded DNA repeats in human cells.

    • Main Results:

    • Identified unusual structural features in DNA repeats that predispose them to expansion.
    • Demonstrated that expanded DNA repeats disrupt critical cellular DNA maintenance processes.
    • Observed significant alterations in gene expression due to expanded repeats, particularly in non-coding regions.

    Conclusions:

    • Expanded DNA repeats are a significant cause of numerous hereditary disorders.
    • The structural peculiarities of these repeats are key to their expansion and subsequent disruption of cellular machinery.
    • The peculiar structures of repeat-containing transcripts play a central role in the pathogenesis of these diseases.