Trinucleotide repeat expansion refers to a genetic phenomenon where a sequence of three nucleotides repeats abnormally and excessively within a specific region of DNA. The trinucleotide repeats are consecutive sets of three DNA bases that are repeated multiple times. This expansion can occur within coding or non-coding regions of the genome.
Trinucleotide repeat expansions are associated with certain genetic disorders known as trinucleotide repeat disorders or triplet repeat disorders. These disorders are typically inherited and can cause a wide range of symptoms and disease manifestations, including neurological, developmental, and cognitive impairments. Examples of trinucleotide repeat disorders include Huntington's disease, Fragile X syndrome, and myotonic dystrophy.
The abnormal expansion of trinucleotide repeats is caused by instability in DNA replication and repair mechanisms. The length of the repeated sequence tends to increase as it is passed from one generation to the next, resulting in the anticipation effect observed in trinucleotide repeat disorders, where symptoms tend to worsen and manifest earlier in subsequent generations.
The expansion of trinucleotide repeats can interfere with normal gene expression and protein production, leading to the disruption of various cellular processes. It is believed that these expansions cause toxicity through various mechanisms, such as altered RNA processing, abnormal protein aggregation, or impaired cellular signaling.
Understanding trinucleotide repeat expansion is important for diagnosing and managing trinucleotide repeat disorders. Research in this area aims to elucidate the molecular mechanisms behind the expansion and develop potential therapeutic strategies to counteract or prevent the pathological consequences associated with these expansions.
