Polygamy, Endogamy and Fumarase deficiency.




Original Question


Q ( B-08 ) ¨ The deficit of enzymes of the TCA cycle is rare, indicating the importance of this pathway for survival. Several cases, however, are on record in which there is a severe deficiency of the enzyme that catalyzes the interconversion between fumarate and malate.  The patient is characterized by severe neurological impairment, encephalomyopathy, and dystonia developing soon after birth. Urine contains abnormal amounts of fumarate and other metabolites of Krebs Cycle. Which of the above enzymes would be deficient?



A ( B-08 ): (d) fumarase (aka fumarate hydratase deficiency)



The twin border communities of Hildale, Utah, and Colorado City, Arizona, have the highest prevalence of known fumarase deficiency cases. And around half the world population of known fumarase deficiency patients have been found in Arizona (Birth Defect is plaguing children in FLDS towns)


Hildale, Utah:




Colorado City, Arizona:







Because of the existence of two closed communities in this area, founded by fundamental polygamist whose families are very inbreeded. In fact, it should be noted that it was not the polygamy which produces this high prevalence of the fumarase deficiency, as could be understood from some press reports, but the fact that this polygamy occurred in a closed population and with a high endogamic behavior. Apparently the founders had a recessive gen for the fumarate deficiency and the marriage among relatives of these two families, or among relatives in the same family, produced the high prevalence of this genetic  disease.


For more information about the history of these communities and the prevalence of fumarase deficiency in them, follow these links:


Polygamist community faces rare genetic disorder



Tracing the Polygamist’s Family Tree






More information about Fumarase deficiency:


Kerrigan, J.F. et al: Fumaric aciduria: clinical and imaging features.


Genetics Home reference: Fumarase deficiency



3 thoughts on “Polygamy, Endogamy and Fumarase deficiency.

  1. My 2 year old daughter has fumarase deficiency. I do want everyone to know that this is an autosomal recessive disease. Although the disease can be passed on through imbreeding , like the cases in Utah, imbreeding is not the only way to get the disease. My husband and I are in no way related. My daughter carries two different mutations on chromosome 1, which gave her the disease. We know of several other cases, none of which the children’s parents are related. I feel like this disease has been labeled the “imbreeding disease” just because of this community in Utah, and that is just not the case. It is the exact same as any other autosomal recessive disease or trait. Blue eyes is an autosomal recessive trait. If two parents both carry the trait for blue eyes, the child just may have blue eyes. I hate that the FLDS is spreading around this trait for the disease, but the disease is not caused by the imbreeding itself, but the trait that is being passed around. Unfortunately my husband and I, and several other families had no idea that we each carried a mutated trait until our daughter was diagnosed. Each person carries several mutated traits, but would never know it unless they met up and married someone that would happen to carry the same or another mutated trait on the same chromosome. I really hope that the bad reputation that this disease carries does not stop research or effort to find a cure. It is so unfortunate to the children like mine that just feel into bad luck with their genes and the only information put out there are articles that have to talk about the polygamy side. There are several of them out there. Please understand that this is not an “imbreeding disease.”

    • You are absolutely right. It happens with all autosomal recessive disease. Of course, the probability that the disease occurs is higher is there is a recessive gen running in a family, and relatives marry, but it does not means that it is the only way in which it can happens.

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