CRISPR基因编辑工具可能导致染色体缺失

The CRISPR molecular scissors have the potential to revolutionize the treatment of genetic diseases.

这是因为它们可以用来纠正基因组中特定的缺陷部分。

This is because they can be used to correct specific defective sections of the genome.

不幸的是，有一个问题：在某些情况下，这种修复可能会导致新的遗传缺陷——就像在慢性肉芽肿病的情况下。

Unfortunately, however, there is a catch: under certain conditions, the repair can lead to new genetic defects – as in the case of chronic granulomatous disease.

这是由苏黎世大学（UZH）临床研究研究人员报告的。

This was reported by a team of researchers at the University of Zurich (UZH).

慢性肉芽肿病是一种罕见的遗传性疾病，大约每12万人中就有1人患病。

Chronic granulomatous disease is a rare hereditary disease that affects about one in 120,000 people.

这种疾病会损害免疫系统，使患者容易受到严重甚至危及生命的感染。

The disease impairs the immune system, making patients susceptible to serious and even life-threatening infections.

它是由NCF1基因的DNA序列中缺少两个碱基引起的。

It is caused by the absence of two letters, called bases, in the DNA sequence of the NCF1 gene.

这种错误导致无法产生一种酶复合物，这种酶复合物在对抗细菌和霉菌的免疫防御中起着重要作用。

This error results in the inability to produce an enzyme complex that plays an important role in the immune defense against bacteria and molds.

该研究小组成功地使用CRISPR系统将缺失的碱基插入到正确的位置。

The research team has now succeeded in using the CRISPR system to insert the missing letters in the right place.

他们在免疫细胞培中进行了实验，这些免疫细胞与患有慢性肉芽肿病的人具有相同的遗传缺陷。

They performed the experiments in cell cultures of immune cells that had the same genetic defect as people with chronic granulomatous disease.

然而，有趣的是，一些修复的细胞现在显示出新的缺陷。

Interestingly however, some of the repaired cells now showed new defects.

发生修复的染色体的整个部分都缺失了。

Entire sections of the chromosome where the repair had taken place were missing.

其原因是NCF1基因的特殊遗星座：它在同一条染色体上出现三次，一个作为活性基因，两个以假基因的形式出现。

The reason for this is the special genetic constellation of the NCF1 gene: it is present three times on the same chromosome, once as an active gene and twice in the form of pseudogenes.

它们与有缺陷的NCF1具有相同的序列，不参与形成酶复合物。

These have the same sequence as the defective NCF1 and are not normally used to form the enzyme complex.

CRISPR的分子剪刀无法区分基因的不同版本，因此偶尔会在染色体上的多个位置切割DNA链——在活性的NCF1基因上以及在假基因上。

CRISPR’s molecular scissors cannot distinguish between the different versions of the gene and therefore occasionally cut the DNA strand at multiple locations on the chromosome – at the active NCF1 gene as well as at the pseudogenes.

当这些片段随后重新连接时，整个基因片段可能会错位或缺失。

When the sections are subsequently rejoined, entire gene segments may be misaligned or missing.

其后果是不可预测的，在最坏的情况下，会导致白血病。

The medical consequences are unpredictable and, in the worst case, contribute to the development of leukemia.

为了将风险降到最低，该团队测试了许多替代方法。

To minimize the risk, the team tested a number of alternative approaches, including modified versions of CRISPR components.

他们还研究了使用保护性分子来减少基因剪刀同时在多个位点切割染色体的可能性。

They also looked at using protective elements that reduce the likelihood of the genetic scissors cutting the chromosome at multiple sites simultaneously.

不幸的是，这些措施都不能完全防止。

Unfortunately, none of these measures were able to completely prevent the unwanted side effects.

“这项研究突出了基于crispr的疗法的有希望和具有挑战性的方面，然而，为了使这种方法在未来更安全、更有效，还需要进一步的技术进步。”UZH生物化学系教授Martin Jinek说。

“This study highlights both the promising and challenging aspects of CRISPR-based therapies,” says co-author Martin Jinek, a professor at the UZH Department of Biochemistry.“However, further technological advances are needed to make the method safer and more effective in the future.”

Cite this article

Raimondi, F., Siow, K.M., Wrona, D. et al. Gene editing of NCF1 loci is associated with homologous recombination and chromosomal rearrangements. Commun Biol 7, 1291 (2024). https://doi.org/10.1038/s42003-024-06959-z