Trinucleotide repeat expansion: Difference between revisions

Latest revision as of 16:27, 16 February 2025

Trinucleotide Repeat Expansion[edit]

Diagram illustrating trinucleotide repeat expansion.

Trinucleotide repeat expansion is a genetic phenomenon where certain sequences of three nucleotides (trinucleotides) are repeated more times than normal in the genome. This expansion can lead to various genetic disorders, depending on the location and extent of the repeat.

Mechanism[edit]

Trinucleotide repeats are sequences in the DNA where a series of three nucleotides is repeated multiple times. These repeats can be found in various parts of the genome, including coding and non-coding regions. During DNA replication, these repeats can become unstable and expand due to slippage of the DNA polymerase. This slippage can cause the newly synthesized strand to misalign with the template strand, leading to an increase in the number of repeats.

Associated Disorders[edit]

Trinucleotide repeat expansions are associated with several genetic disorders, often referred to as trinucleotide repeat disorders. These disorders are typically characterized by neurological symptoms and can vary in severity. Some well-known disorders include:

The severity and onset of these disorders often correlate with the number of repeats; larger expansions tend to result in more severe symptoms and earlier onset.

Genetic Anticipation[edit]

Illustration of genetic anticipation in trinucleotide repeat disorders.

A notable feature of trinucleotide repeat disorders is genetic anticipation, where the symptoms of a genetic disorder become more severe or appear at an earlier age as the disorder is passed on to the next generation. This is due to the tendency of the repeat expansions to increase in size when transmitted from parent to offspring.

Diagnosis and Testing[edit]

Diagnosis of trinucleotide repeat expansion disorders typically involves genetic testing to determine the number of repeats in the relevant gene. Techniques such as polymerase chain reaction (PCR) and Southern blotting are commonly used to assess repeat length.

Treatment and Management[edit]

Currently, there is no cure for trinucleotide repeat expansion disorders, but various treatments can help manage symptoms. These may include medications to control neurological symptoms, physical therapy, and supportive care. Research is ongoing to find potential therapies that target the underlying genetic causes.

Related Pages[edit]

@@ Line 1: / Line 1: @@
-{{Short description|Genetic mutation involving the repetition of a sequence of three nucleotides}}
+== Trinucleotide Repeat Expansion ==
-{{Use dmy dates|date=October 2023}}
-'''Trinucleotide repeat expansion''' is a type of [[genetic mutation]] that involves the repetition of a sequence of three [[nucleotides]] (trinucleotide) in the [[DNA]] of a gene. This expansion can lead to various genetic disorders, depending on the gene affected and the number of repeats.
+[[File:WikiStructures.png|thumb|right|Diagram illustrating trinucleotide repeat expansion.]]
-==Mechanism==
+'''Trinucleotide repeat expansion''' is a genetic phenomenon where certain sequences of three nucleotides (trinucleotides) are repeated more times than normal in the genome. This expansion can lead to various genetic disorders, depending on the location and extent of the repeat.
-Trinucleotide repeat expansions occur when the number of repeats of a specific trinucleotide sequence increases beyond a normal range. This can happen during [[DNA replication]] when the DNA polymerase "slips" and adds extra repeats. The most common trinucleotide repeats are CAG, CTG, CGG, and GAA.
-==Associated Disorders==
+== Mechanism ==
-Trinucleotide repeat expansions are associated with several [[genetic disorders]]. Some of the most well-known include:
-* [[Huntington's disease]]: Caused by an expansion of CAG repeats in the HTT gene.
+Trinucleotide repeats are sequences in the DNA where a series of three nucleotides is repeated multiple times. These repeats can be found in various parts of the genome, including coding and non-coding regions. During DNA replication, these repeats can become unstable and expand due to slippage of the DNA polymerase. This slippage can cause the newly synthesized strand to misalign with the template strand, leading to an increase in the number of repeats.
-* [[Fragile X syndrome]]: Results from an expansion of CGG repeats in the FMR1 gene.
-* [[Myotonic dystrophy]]: Involves CTG repeat expansions in the DMPK gene.
-==Pathophysiology==
+== Associated Disorders ==
-The expansion of trinucleotide repeats can disrupt normal gene function in several ways. In some cases, the expanded repeats lead to the production of abnormal proteins that aggregate and cause cellular damage. In other cases, the expansion affects gene expression, leading to a loss of function.
-==Diagnosis==
+Trinucleotide repeat expansions are associated with several genetic disorders, often referred to as [[trinucleotide repeat disorders]]. These disorders are typically characterized by neurological symptoms and can vary in severity. Some well-known disorders include:
-Diagnosis of disorders caused by trinucleotide repeat expansions typically involves genetic testing. Techniques such as [[polymerase chain reaction]] (PCR) and [[Southern blotting]] are used to determine the number of repeats in a gene.
-==Treatment==
+* [[Huntington's disease]]
-Currently, there are no cures for disorders caused by trinucleotide repeat expansions. Treatment focuses on managing symptoms and may include medications, physical therapy, and supportive care.
+* [[Fragile X syndrome]]
+* [[Myotonic dystrophy]]
+The severity and onset of these disorders often correlate with the number of repeats; larger expansions tend to result in more severe symptoms and earlier onset.
-==Research==
+== Genetic Anticipation ==
-Ongoing research aims to better understand the mechanisms of trinucleotide repeat expansions and develop targeted therapies. Gene editing technologies, such as [[CRISPR-Cas9]], are being explored as potential treatments.
-==Related pages==
+[[File:WikiStructures.png|thumb|left|Illustration of genetic anticipation in trinucleotide repeat disorders.]]
-* [[Genetic mutation]]
+A notable feature of trinucleotide repeat disorders is [[genetic anticipation]], where the symptoms of a genetic disorder become more severe or appear at an earlier age as the disorder is passed on to the next generation. This is due to the tendency of the repeat expansions to increase in size when transmitted from parent to offspring.
+== Diagnosis and Testing ==
+Diagnosis of trinucleotide repeat expansion disorders typically involves genetic testing to determine the number of repeats in the relevant gene. Techniques such as [[polymerase chain reaction]] (PCR) and [[Southern blotting]] are commonly used to assess repeat length.
+== Treatment and Management ==
+Currently, there is no cure for trinucleotide repeat expansion disorders, but various treatments can help manage symptoms. These may include medications to control neurological symptoms, physical therapy, and supportive care. Research is ongoing to find potential therapies that target the underlying genetic causes.
+== Related Pages ==
+* [[Genetic disorder]]
 * [[DNA replication]]
-* [[Huntington's disease]]
+* [[Genetic testing]]
-* [[Fragile X syndrome]]
-==References==
+{{Genetics}}
-{{Reflist}}
 [[Category:Genetic disorders]]
-[[Category:Mutation]]
+[[Category:Genetics]]
-[[Category:DNA]]
-[[File:WikiStructures.png|thumb|right|Diagram illustrating the structure of DNA and the location of trinucleotide repeats.]]