Is it possible to edit one's genome to produce a desired phenotype?

[Baloo]

I'm wondering if it is possible edit someone's genome (someone already living) to produce certain phenotypes, such as hair quality. Certainly, you would have to cancel out some existing genes. But I'm just wondering if its possible.

 

 

Certain examples would be like manipulating hair thickness, the location of the hairline, hair color, straightness etc.

 

 

 

 

 

[Maximilian]

In general, it would not be necessary to "cancel out some existing genes", unless the specific phenotype requires it.

 

Yes, it is possible. Simple in theory, but very, very, very complicated in practice.

 

For example, hair thickness, color, and straightness could be modified by inserting the appropriate gene variants. I don't think the hairline location could be manipulated genetically in an adult because that involves the expression of genes during the development rather than genes being currently expressed. I mean, you could do it, but that is not simple in theory at all. You'd have better luck performing surgery.

[Baloo]

Thanks for you answer Max. But how do you know hairline location "involves the expression of genes during the development rather than genes being currently expressed"? I don't see how hairline is any different than thickness, color, and straightness as they relate to gene expression.

 

Second, where do you think the greatest difficulty lies? My understanding of genome editing is that the hardest part is creating a pathway for the genes that doesn't trigger a violent (and possibly deadly) immune response.

[CharonY]

There are probably too many issues to list them comprehensively but things that pop into my mind are:

- we do not know how precisely the proteins have to work together to result in a specific phenotype. The interplay of the components is very intricate, and quantitative (i.e. it is not a on/off situation but rather requires a delicate balance)

- even if we knew the components and the required equilibria, we do not know how to carefully balance them out. Most genetic manipulations are very heavy-handed

- even if we could do that, we lack the means to to so coordinated in a large number of cell (e.g. within a tissue)

- even if we could do that, there is a chance that we disrupt existing functions. No metabolic activity happens in isolation. If you tweak things on one end, a lot of further elements are getting affected. While we are starting to developing techniques to monitor it (on the cellular level) we still lack a comprehensive view of all the events and their consequences on a more complex level.

 

In short, we do not know enough.

[iRNAblogger]

Also (to add to the concerns above), "editing" a genome of a person or animal that is already past the zygotic stage is virtually impossible. We wouldn't even get to the stage where we could worry about negative effects of having the gene integrated into our genomes. Occasionally this phenomenon does occur, and it more often than not results in cancer.

 

In order to "edit" a person's genome, you would have to transform that person's cells with 100% efficiency (at this point in time, this is absolutely impossible). In addition to transforming the person's cells with 100% efficiency, you would need to expose each and every one of that person's cells to the transformation vector (virtually impossible). Even if you could accomplish these above steps, it is extremely unlikely that you could ensure integration of the gene in a stable location (it is likely that you would integrate into another gene, which could result in lethality or cancerous growth for that particular cell's progeny, or into a silenced area of the genome, which would result in non-expression).

 

You WOULD be able to do this "editing" if you had access to the zygote or gametes (pre-fertilization) and could perform the necessary transformation procedure and then screening process (which is how it is done in mice/zebra fish/other lab animals and plants). However, it is generally considered unethical to genetically transform a human zygote due to the concerns brought up by previous answers.

 

Perhaps in the future, when science technology has far, far surpassed that of today, will we be able to consider genome "editing" of humans.