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- A trinucleotide repeat expansion, also known as a triplet repeat expansion, is the DNA mutation responsible for causing any type of disorder categorized as a trinucleotide repeat disorder. These are labelled in dynamical genetics as dynamic mutations. Triplet expansion is caused by slippage during DNA replication, also known as "copy choice" DNA replication. Due to the repetitive nature of the DNA sequence in these regions, 'loop out' structures may form during DNA replication while maintaining complementary base pairing between the parent strand and daughter strand being synthesized. If the loop out structure is formed from the sequence on the daughter strand this will result in an increase in the number of repeats. However, if the loop out structure is formed on the parent strand, a decrease in the number of repeats occurs. It appears that expansion of these repeats is more common than reduction. Generally, the larger the expansion the more likely they are to cause disease or increase the severity of disease. Other proposed mechanisms for expansion and reduction involve the interaction of RNA and DNA molecules. In addition to occurring during DNA replication, trinucleotide repeat expansion can also occur during DNA repair. When a DNA trinucleotide repeat sequence is damaged, it may be repaired by processes such as homologous recombination, non-homologous end joining, mismatch repair or base excision repair. Each of these processes involves a DNA synthesis step in which strand slippage might occur leading to trinucleotide repeat expansion. The number of trinucleotide repeats appears to predict the progression, severity, and age of onset of Huntington's disease and similar trinucleotide repeat disorders. Other human diseases in which triplet repeat expansion occurs are fragile X syndrome, several spinocerebellar ataxias, myotonic dystrophy and Friedreich's ataxia. (en)
- 三核苷酸重复序列扩增（英語：Trinucleotide repeat expansion, Triplet repeat expansion），也称三核酸重复序列扩增、三核苷酸重复扩增、三核苷酸扩增等，是一种可能导致的DNA突变。在中被称为。 在DNA复制中，三核苷酸重复序列扩增由DNA复制时的滑动现象（英語：slippage）造成。DNA序列在不少区域都有重复序列，使得母链和子链碱基互补配对有时会产生环状结构。如果环状结构发生于子链则DNA複製後重复序列的重复次数会增加，发生于母链则重复次数减少，重复次数增加的概率被认为大于减少的概率。而重复序列扩增的规模越大，越有可能导致疾病，其导致的疾病也越严重。DNA和RNA的互动也可能参与了三核苷酸重复序列扩增这一导致序列不稳定的现象中。 DNA修復也会导致三核苷酸重复序列扩增。三核苷酸重复序列损伤时，会引发同源重組、非同源性末端接合、 错配修复、碱基切除修复等修复机制来修复损伤的DNA。这些过程中，错配碱基切除后往往需要同DNA复制一般重新配对，因而有概率产生三核苷酸重复序列扩增。 三核苷酸重复序列的重复次数与亨丁頓舞蹈症等一众三核苷酸重复序列疾病的病程、危重程度、发病年龄正相关。 (zh)
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- 三核苷酸重复序列扩增（英語：Trinucleotide repeat expansion, Triplet repeat expansion），也称三核酸重复序列扩增、三核苷酸重复扩增、三核苷酸扩增等，是一种可能导致的DNA突变。在中被称为。 在DNA复制中，三核苷酸重复序列扩增由DNA复制时的滑动现象（英語：slippage）造成。DNA序列在不少区域都有重复序列，使得母链和子链碱基互补配对有时会产生环状结构。如果环状结构发生于子链则DNA複製後重复序列的重复次数会增加，发生于母链则重复次数减少，重复次数增加的概率被认为大于减少的概率。而重复序列扩增的规模越大，越有可能导致疾病，其导致的疾病也越严重。DNA和RNA的互动也可能参与了三核苷酸重复序列扩增这一导致序列不稳定的现象中。 DNA修復也会导致三核苷酸重复序列扩增。三核苷酸重复序列损伤时，会引发同源重組、非同源性末端接合、 错配修复、碱基切除修复等修复机制来修复损伤的DNA。这些过程中，错配碱基切除后往往需要同DNA复制一般重新配对，因而有概率产生三核苷酸重复序列扩增。 三核苷酸重复序列的重复次数与亨丁頓舞蹈症等一众三核苷酸重复序列疾病的病程、危重程度、发病年龄正相关。 (zh)
- A trinucleotide repeat expansion, also known as a triplet repeat expansion, is the DNA mutation responsible for causing any type of disorder categorized as a trinucleotide repeat disorder. These are labelled in dynamical genetics as dynamic mutations. Triplet expansion is caused by slippage during DNA replication, also known as "copy choice" DNA replication. Due to the repetitive nature of the DNA sequence in these regions, 'loop out' structures may form during DNA replication while maintaining complementary base pairing between the parent strand and daughter strand being synthesized. If the loop out structure is formed from the sequence on the daughter strand this will result in an increase in the number of repeats. However, if the loop out structure is formed on the parent strand, a decr (en)
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- Trinucleotide repeat expansion (en)
- 三核苷酸重复序列扩增 (zh)
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