单一核苷酸,X染色体综合征 z-bo 2020-10-17 336

　　In the latest research report published in the international journal "Journal of Cell Biology", researchers at Jesse University found through their research that a single nucleotide change can lead to syndrome X that is susceptible to infection in individuals. Fragile X syndrome is usually caused by the deletion of a gene on the X chromosome called Fragile X Mental Delay 1 (FMR1), and 1 in 230 women carry a mutation in this gene. .. A person has a variation. Even if there is an extra DNA repetitive sequence at the end of the FMR1 gene, when the FMR1 gene is passed from mother to offspring, the repetitive sequence of these DNA sequences will expand and the gene will be turned off.

　　It prevents the expression of proteins important for cognitive function. In a previous study, researchers found that a special site near the FMR1 gene can turn on DNA replication, but it can inactivate it in fragile X embryonic stem cells. This inactivation changes the process of cell division. The way the FMR1 gene replicates poses a major problem in the DNA replication process. However, what surprised the researchers is that the special changes in the DNA sequence near the FMR1 gene, that is, the changes in single nucleotide polymorphisms, are directly related to the repeated amplification of certain specific mutation vectors. , There are more single nucleotides. The morphology overlaps in the inactive replication area of fragile X embryonic stem cells. DNA nucleotides contain four bases (ATCG).

　　According to researchers, normal embryonic stem cells have a timine base at the SNP site and active replication region, while fragile X chromosome cells have cytosine. After studying offspring embryonic stem cells with fragile X mutations, we found that these cells have a normal replication pattern with timine bases. This means that nucleosides will not repeat over time. Extension of acid sequence.

　　In this study, when the FMR1 gene is passed from mother to offspring, replacing adenine with cytosine will inactivate the DNA replication region, thereby increasing the risk of DNA repeat amplification, which leads to individual fragile X. It has been proven to cause chromosome synthesis.