There are a couple of small towns on the border between Utah and Arizona that are basically feudal theocracies, ruled by a particularly nasty splinter sect of polygamist Mormons. It’s got some truly ugly social consequences — daughters are prizes given away to church leaders, while sons are competitors who are driven away — but now it turns out that there also some biological consequences. The community is deeply inbred, and their prize is the possession of the highest rate of fumarase deficiency in the world, with at least 20 afflicted children in the last 15 years. Fumarase is an enzyme in the Krebs cycle; deleterious mutations in these genes cause a metabolic disorder called fumarase deficiency.
It’s not a nice innocuous disease. It’s variable in its severity, but bad cases lead to debilitating mental retardation, frequent seizures, characteristic appearance (a large head, coarse features), and death. With care, affected individuals can live for many years, but they’ll never be self-sufficient and they do require near-constant attention.
And because it is widespread in a small isolated community, that for various reasons (including religion) is neither a desirable destination for new residents nor will its population try to integrate with the outside world, it’s going to get worse. Half the children born to a pair of carriers will be carriers of the disease themselves, and those nice big Mormon families produce lots of children. Not only are the young girls in this community forced to marry and start spawning baby after baby, but compound the horror with the idea that some will be having children who will need to have their diapers changed for 20 years…


