My wife was told a story from Khmer Rouge times - that Pol Pot was afraid of people who derived from Prey Veng, concerned that they wouldn't die (from starvation, sickness or infection).

First I was told that my wife has a Haemoglobin disorder. No normal (red) blood cells. A genetic condition inherited from her parents. A genetic mutation. "You'll have to monitor your blood levels for life" she was told. They'd seen the more common single E genome before in people from SE Asia who were tested in the U.K. It's a recessive inheritance gene with a dominant kicker AE or EA - I'm not sure which is scientifically correct.

What is meant by the term recessive gene?
A recessive gene or allele is one in which the effect is not tangible, or is masked by the effects of the dominant gene. The recessive trait may be expressed when the recessive genes are in homozygous condition or when the dominant gene is not present.

Some SE Asians have the single E genome along with the dominant A genome that most of us have. It is very rare to have the homozygous double EE haemoglobin.

A genome specialist told me that one in four have the Southern European Thalassemia genome and that one in twelve has the blood disorder Sickle Cell Anemia. However, only one in two hundred and forty-six thousand have a single E genome.

The concern is that a carrier of E (or EE) will produce offspring with a carrier of Sickle Cell or Thalassemia. The doctor in uncertain terms let it be known that that would be a big problem.

When I did my own research I found this study (link below) from a team including the current Cambodian government along with a university in BC Canada and the very same university my wife's samples were being sent to - Oxford University Hospital. I found out that only some people from the few communes in the study have the genetic haemoglobin disorder that means they have no normal blood cells commonly known as EE genome disorder.

https://academic.oup.com/jn/article/145/1/134/4585759

There was a CEO thread/discussion on this.
general-chatter/thalassemia-cambodia-t29913.html

And for those who are interested, there is a list of related articles here:
https://pubmed.ncbi.nlm.nih.gov/27117566/