Growing both sperm and egg cells from the SAME person? Oh My!

[kenny]

One thing that only straight couples have enjoyed is being able to have a child that is genetically half mom and half dad.
Gay couples can't do that because they need a donor sperm or egg.

In Berkeley CA biomedical startups aim to develop new technology.
The goal is to allow two women, or two men, to have children with the DNA of both parents by using steam cells to generate sperm and eggs from one person.
This could also help infertile people have children.

WOW!

If one person had a child from an egg or sperm generated from their own cells, would this be inbreeding?
Would that parent be called mom?, dad?, moad?, daom?

Ethicists are gonna have a field day with this, and I fear the pope is gonna have a heart attack.

Listen to NPR's 8-minute audio clip on this.

https://www.npr.org/sections/health-shots/2023/07/15/1184298351/conception-human-eggs-ivg-ivf-infertility

 

[LilAlex]

So not a great idea!

You probably shouldn't even make a baby with a partner from your same small endogamous group (like the Old Order Amish) because the prevalence of "rare-elsewhere" recessive mutations/polymorphisms can be super-high (from a genetic bottleneck -- they are typically descended from a very small "founder" population) such that you have a good chance of mating with someone with the same should-be-rare genetic variant and then have a one-in-four chance of making a severely affected baby. Ashkenazi Jews know to screen for Tay Sachs -- and they are not even very endogamous now. Plus, there are thousands of recessive genetic syndromes and I suspect that most have not even been identified yet.

So making a baby with yourself means having a super-high chance of producing a kid with two copies of the same rare and detrimental gene variant. It is way worse than "cloning" yourself because with cloning, at least you would only get the same "genotype" as the donor -- meaning only one copy of each "defective" gene -- instead of rolling the meiosis dice and risking two "bad" copies.

I did not read/listen to the article but, genetically-speaking, this sounds insane. I may be wrong.

EDIT: I guess the actual practical use is that any same-sex couple could make a baby, provided there were an available uterus. But using this tech to make a baby with yourself would be nuts.

 

[RMOO]

I didn't read the whole article, but was relieved to read that the intent is to be able to grow the missing genetic half (egg or sperm) from one of the partners in a same sex couple, and not double up on genetic material from a single individual.

 

[kenny]

But if this is successful it seems possible to grow sperm from the stem cells and DNA of one single woman and grow eggs from a man's biological material.
So, regardless of intent, an individual with the funds theoretical could make a kid using only their own DNA.

What would that even mean?
Would it be a different person than their parent?
Would it still have a 50% chance of being a girl, or vice versa?

We know inbreeding increases the odds of bad outcome.
Would breeding with yourself, for lack of a better term, result of such bad outcomes on steroids?

I'm not arguing this whole idea is good, bad, right, or wrong, but is surely does fills one (at least me) with questions and wonder.

 

[RMOO]

Well, any medical advancement has the potential for misuse by a miscreant. I remember similar arguments being made at the dawn of test tube babies and sheep cloning. If someone wanted to duplicate themselves, they could probably technically do it now with cloning. But, ethical medical professionals will not double up on DNA because they know the risk in the outcome.

 

[LilAlex]

Would breeding with yourself, for lack of a better term, result of such bad outcomes on steroids?

Yes. It's way worse, genetically speaking, than mating with your sibling -- which is discouraged in most cultures.

 

[Avondale]

Would it still have a 50% chance of being a girl, or vice versa?

Two women would always have a daughter. No Y chromosome to make a boy.

Two guys... We need to grow an egg from one of them, and we need a way to be absolutely positively sure that egg will always have an X chromosome. Imagine if a baby has YY chromosomes... We don't even know what that would be like, at present it's not really objectively possible. In any case, creating a baby with a genetic defect would be wildly unethical.

And speaking of wildly unethical, using this technology to make a baby with yourself would be forbidden 10000000%.

 

[kenny]

Devil's advocate here.

AFAIK when a man and a woman both carry a gene that elevates odds for passing down a genetic illness it increases the odds their offspring will develop the illness.
Makes sense.

But, if both sperm and egg are from only one of the above persons (who carried the gene but did not develop the illness) wouldn't the child also carry the gene but not get the illness?
After all, the kid is an 100% genetic copy of only one person.

Serious question.

I realize this topic makes many queasy.
Not me.
I'm just intrigued with the actual genetic science and the math of this new possibility, not whether something is okay or not okay, good or bad, moral or immoral.

Also, my curiosity does not mean I support all this.
Curious people discussing potential ramifications of new things is interesting,

 

[RMOO]

But would it be an exact copy? Thinking back to college biology, you get half you genes from your mother and half from your father. Which genes are in each individual egg or sperm? It’s a different combo in each egg or sperm- or else all of my kids would be exact replicas of each other (same mother and father)

 

[kenny]

But would it be an exact copy? Thinking back to college biology, you get half you genes from your mother and half from your father. Which genes are in each individual egg or sperm? It’s a different combo in each egg or sperm- or else all of my kids would be exact replicas of each other (same mother and father)

Granted, good point.

But a body makes many eggs or many sperm.
So, those will vary.

A manufactured egg and sperm are not a random sample from a large selection.
Apparently (and this shows my lack of knowledge regarding this new process) they are the result of a stem cell and the DNA in a cell from the body.
Let's say the cell contributing the DNA is a blood cell, or, say, a lung cell, or whatever.
Are all the lung cells in one person genetically identical, or do they vary?

 

[Starstruck8]

AFAIK when a man and a woman both carry a gene that elevates odds for passing down a genetic illness it increases the odds their offspring will develop the illness.
Makes sense.

But, if both sperm and egg are from only one of the above persons (who carried the gene but did not develop the illness) wouldn't the child also carry the gene but not get the illness?
After all, the kid is an 100% genetic copy of only one person.

The problems with in-breeding result from rare recessive 'bad' genes. Having a single copy of such a gene causes little or no problem. Having a double copy is disastrous. Most of us probably carry single copies of quite a few such genes without noticing.

Suppose you carry a single copy of such a gene. If you clone yourself, the clone will also carry a single copy. That won't cause a problem. Or at least, the clone won't be any worse off than you. But 'self-mating' (eggs and sperm made from the same person) differs from cloning. A child produced by self-mating is not a clone of its parent. There is a 50% chance that the egg will have your bad gene, and an independent 50% chance that the sperm will. So there is a 25% chance the child will have a double copy. This applies independently to each of your recessive bad genes. So the child is very likely to get a double copy of at least one of them. Not good.

Relevant trivia: Most flowering plants do in fact produce eggs and sperm (pollen) from themselves. Most have mechanisms to prevent self-pollination, or at least reduce it. But it's still pretty frequent in some species. What makes plants different from us is that they can produce vast numbers of seeds with relatively little investment in each seed. So they can survive the reduced viability from selfing, if it means that they get to produce more seeds. Humans, with nine months gestation and a long childhood, don't work like that (even leaving aside the ethical issues).

But a body makes many eggs or many sperm.
So, those will vary.

A manufactured egg and sperm are not a random sample from a large selection.
Apparently (and this shows my lack of knowledge regarding this new process) they are the result of a stem cell and the DNA in a cell from the body.
Let's say the cell contributing the DNA is a blood cell, or, say, a lung cell, or whatever.
Are all the lung cells in one person genetically identical, or do they vary?

As I understand it, all our body cells carry our full genome. But in different sorts of cells, the chromosomes are chemically marked (e.g. by 'methylation') so that only particular genes are expressed in those cells. A key part of artificially making eggs or sperm is to remove this marking.

Here is the bit of high school biology that I think you may be missing. (Search on 'meiosis'.) Apologies if I'm mistaken. Our chromosomes of our body cells come in pairs (2 x 23 = 46). We get one chromosome of each pair from each of our parents. The chromosomes of our gametes (egg or sperm cells) are not paired. (There are only 23 of them). Each of the gamete chromosomes has some of the mother's DNA and some of the father's. Which parts or each parent's DNA get into each gamete chromosome is (sort of) random. This is what makes each egg cell and each sperm cell different.

 

[kenny]

Thanks Starstruck8.
Fascinating field!

 

[RMOO]

It is extremely fascinating. Scary too, as all new science is, until things shake out and we see exactly how it will be used.