Genome editing facts for kids

Genome editing is a type of genetic engineering.

DNA is inserted, replaced, or removed from a genome using artificially engineered nucleases, or "molecular scissors". The nucleases make specific double-strand breaks (DSBs) at desired places in the genome. The cell’s own mechanisms repair the induced break(s) by natural processes.

At present there are four families of engineered nucleases being used.

To understand the function of a gene or a protein, one interferes with it in a sequence-specific way, and watches it's effects on the organism. However, in some organisms it is difficult or impossible to do site-specific mutation. Therefore more indirect methods have to be used. Examples are:

• Silencing the gene of interest by short RNA interference (siRNA). However, gene disruption by siRNA can be variable and incomplete.

• Genome editing with nucleases such as ZFN. This is different from siRNA. The engineered nuclease (the enzyme which cuts the DNA) is able to modify DNA-binding. Therefore it can in principle cut any targeted position in the genome, and introduce change the sequences for genes which cannot be specifically targeted by conventional RNAi.

Genome editing was chosen by Nature Methods as the 2011 Method of the Year. The technique is already being used, but implanting modified embryos into a woman is not yet permitted.

The CRISPR/Cas9 method

In 2017 this system was announced as one of the biggest scientific achievements of the year. Cas9 is an enzyme which with a guide RNA, can put a new sequence of DNA into a genome. Sir John Skehel said "That might allow you to knock out a particular gene in a cell, or introduce a particular gene, or correct a particular mutated gene that you want to work better".

Images for kids

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  Groups of engineered nucleases. Matching colors signify DNA recognition patterns

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  General overview of the TALEN process

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  Synthetic DNA is repeatedly introduced at multiple targeted areas of the chromosome and/or loci and then is replicated producing cells with/without mutations.

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  Plants, animals and human genes that are successfully targeted using ZFN, which demonstrates the generality of this approach

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  Overview of GEEN workflow and editing possibilities

See also

In Spanish: Edición de genoma para niños