MRKH Syndrome

[stewamax]

BBC's online news yesterday (24th) ran a story about young ladies with MRKH - a congenital serious abnormality or total lack of uterus or vagina that affects one in 5000 women (NHS's figure).
Given that it is present from birth, totally vitiates reproduction, and that '1 in 5000' sounds not that rare, it made me wonder why natural selection had not rendered it very uncommon indeed.

[GoSeigen]

BBC's online news yesterday (24th) ran a story about young ladies with MRKH - a congenital serious abnormality or total lack of uterus or vagina that affects one in 5000 women (NHS's figure).
Given that it is present from birth, totally vitiates reproduction, and that '1 in 5000' sounds not that rare, it made me wonder why natural selection had not rendered it very uncommon indeed.

Maybe because there are males and females? Or are you saying it also renders males infertile and therefore unable to pass it on?

Or it could be the result of the combined action of a number of genes, some of which may be recessive and some of which may have other functions that are vital or useful to preserve.



GS

[mc2fool]

BBC's online news yesterday (24th) ran a story about young ladies with MRKH - a congenital serious abnormality or total lack of uterus or vagina that affects one in 5000 women (NHS's figure).
Given that it is present from birth, totally vitiates reproduction, and that '1 in 5000' sounds not that rare, it made me wonder why natural selection had not rendered it very uncommon indeed.

Not every medical issue that is congenital (present at birth) is genetic or hereditary.

Consider Down syndrome for example. It is genetic in the sense that the foetus has abnormal genes -- an extra chromosome 21 -- but that's not passed on from the parents' DNA, they are genetically normal, but is the result of just a random error in cell division.

The causes of MRKH seem to be "elusive". and may or may not have a hereditary component.

"The majority of Müllerian agenesis cases are characterized as sporadic, but familial cases have provided evidence that, at least for some patients, it is an inherited disorder." https://en.wikipedia.org/wiki/Müllerian_agenesis

[servodude]

BBC's online news yesterday (24th) ran a story about young ladies with MRKH - a congenital serious abnormality or total lack of uterus or vagina that affects one in 5000 women (NHS's figure).
Given that it is present from birth, totally vitiates reproduction, and that '1 in 5000' sounds not that rare, it made me wonder why natural selection had not rendered it very uncommon indeed.

Not every medical issue that is congenital (present at birth) is genetic or hereditary.

Consider Down syndrome for example. It is genetic in the sense that the foetus has abnormal genes -- an extra chromosome 21 -- but that's not passed on from the parents' DNA, they are genetically normal, but is the result of just a random error in cell division.

The causes of MRKH seem to be "elusive". and may or may not have a hereditary component.

"The majority of Müllerian agenesis cases are characterized as sporadic, but familial cases have provided evidence that, at least for some patients, it is an inherited disorder." https://en.wikipedia.org/wiki/Müllerian_agenesis

But put simply the reason it has not been "bred out" by natural selection is because it's not something one just inherits from their mum.
It might take multiple genes, it might be spontaneous, it might be developmental rather than genetic
- but it's not working like eye colour in terms of genetic inheritance

[odysseus2000]

It would be interesting to see if this condition has always been present or whether it has become more common in recent years. If the latter it may be due to some toxic environmental chemicals that are now present but which did not exist before.

Regards,

[Arborbridge]

1 in 5000 seems to me not rare, but notable - yet I am an ignoramus who has never heard of this.

Arb.

[swill453]

It would be interesting to see if this condition has always been present or whether it has become more common in recent years. If the latter it may be due to some toxic environmental chemicals that are now present but which did not exist before,

What would you put it down to if it turned out that it was less common than it used to be?

Scott.

[servodude]

It would be interesting to see if this condition has always been present or whether it has become more common in recent years. If the latter it may be due to some toxic environmental chemicals that are now present but which did not exist before,

What would you put it down to if it turned out that it was less common than it used to be?

Scott.

Easy tiger!
Nothing wrong with a hypothesis, iff it's handled properly and doesn't affect the analysis
I'd probably consider the (increasing) age of becoming a mother first though given genetics, mutation and stuff
- it would be very difficult to pull it apart from environment though... not least as it affords a longer time for environmental effects to influence things

[odysseus2000]

What would you put it down to if it turned out that it was less common than it used to be?

Scott.

Easy tiger!
Nothing wrong with a hypothesis, iff it's handled properly and doesn't affect the analysis
I'd probably consider the (increasing) age of becoming a mother first though given genetics, mutation and stuff
- it would be very difficult to pull it apart from environment though... not least as it affords a longer time for environmental effects to influence things

The data on how rates of illness change with time is hard to get hold off, but the overwhelming trend has been for increased life expectancy with some dips. There are many putative reasons: Better nutrition, better health care, less pollution,… As mentioned it is hard to deconvolve the various factors. For many years there was no consensus on whether tobacco smoking was harmful & there are various industry groups trying to make the case that another industries products are the culprits. One of the, once thought seminal studies, on heart disease, which suggested it was dietary fat, was sponsored by the sugar industry. Nonetheless there are clear connections sometimes found. The anti morning sickness nausea drug thalidomide was clearly shown to produce birth defects & was urgently withdrawn. From my perspective I feel it is always worth asking if there have been historical changes in illness & if so try & find what made things better or worse. As time progresses if proper records are kept we may gather information on what is good or bad in a statistically significant way.

Regards,