A super rare disease that results from polygamous inbreeding is reportedly affecting children at alarming rates — and it has no cure.

Experts say inbreeding in a Mormon community near the border of Arizona with Utah is responsible for a rare — now common — genetic condition called fumarase deficiency that is causing children of polygamist families to suffer from extreme physical and mental dysfunctions. Experts are now warning members of the Fundamentalist Church of Jesus Christ of Latter-Day Saints (or FLDS) enclave of the dangers of conceiving inbred offspring.

Dr. Theodore Tarby is a specialist in the field of rare childhood diseases. He was instrumental in uncovering the negative impact of polygamist practices on childbirth as far back as 1990. At the time, an FLDS mother sought treatment at his office on behalf of her son, according to a report from Daily Mail.

Members who belong to FLDS are often confused with the Mormon Church of Jesus Christ of Latter-day Saints (or LDS). The chief difference is that the former practices polygamy while the latter forbids the act of having sexual relations or marriage among kin.

Prophet Joseph Smith founded Mormonism in 1840 and led the religion until his death in 1844. Brigham Young founded the first settlement in Utah in 1847. During that period, the Mormon Church practiced plural marriage under both men’s leadership, according to Life After.

In 1890, the LDS church outlawed the practice of polygamy to conform to requirements for Utah statehood. In the 1930s, Fundamentalists still practicing polygamy were excommunicated. The FLDS Church formed as a result. The convicted felon Warren Jeffs leads it today. An upcoming docuseries will feature Jeffs’ sons.

The boy brought to Dr. Tarby, 10, was presented with “unusual facial features” such as deformed or asymmetrical ears and eyes. Dr. Tarby also observed that the child was severely mentally challenged.

At the time, he couldn’t properly diagnose the boy while waiting for the results of a urine test; medical literature lacked definitive causes. Once he received the final urinalysis, it was clear the boy had fumarase deficiency (or FD).

Genetics Home Reference says the “extremely rare” disorder affects about 100 people, primarily in an “isolated religious community in the southwestern” part of the country — the region explored in this report.

“Fumarase deficiency is a condition that primarily affects the nervous system, especially the brain. Affected infants may have an abnormally small head size (microcephaly), abnormal brain structure, severe developmental delay, weak muscle tone (hypotonia), and failure to gain weight and grow at the expected rate (failure to thrive).”

The site talks about what a sufferer may experience with fumarase deficiency: seizures, deformities of the face — as mentioned of the boy above — micrognathia (tiny jaw), ocular hypertelorism (wide-spaced eyes), sunken nasal bridge, and a larger than normal liver and spleen. A person with the genetic malady may also have low blood count and lower life expectancy.

Simply put, FD occurs when someone doesn’t possess the enzyme fumarase that is responsible for a host of biological tasks that support energy transportation on the cellular level. The largest impact of the deficiency is in the brain.

Radiology reports show that a person with FD is missing a portion of their brain. Consequently, they suffer from seizures and need assistance with mobility. Telltale signs of the disease are low scores on intelligence tests.

Dr. Tarby said case studies at the time showed only about 13 reported cases globally. Statistically, it meant the condition was so rare that it occurred in only one in 400 million people. Soon, Tarby diagnosed the boy’s sister with the condition.

Fearing that others in the inbreeding community may be afflicted with FD, Tarby began collecting data from polygamist families. He soon diagnosed eight additional cases and observed that all the patients had the classic signs of the illness.

Tarby and his team made an astounding conclusion: children born out of polygamy had risk factors of 1 million times the global averages. Researchers say inbreeding from polygamous relationships is the chief reason behind the now-common disease in the introverted Mormon community. It’s the byproduct of generational inbreeding.

They traced the defective gene back to the founders of the LDS Church. Tarby and his group say approximately 80 percent of the FLDS sect is related to the Mormon founders by blood.

Inbreeding/genetic bottlenecks are bad: new evidence from a polygamous town in Utahhttps://t.co/6l9a1lRMwR — Claire Lehmann (@clairlemon) July 28, 2017

Mark Stoneking works as a geneticist at the Max Planck Institute for Evolutionary Anthropology in Germany. He weighed in on the findings.

“With polygamy, you’re decreasing the overall genetic diversity because a few men are having a disproportionate impact on the next generation. Random genetic mutations become more important.”

There is no cure or effective treatment for the fumarase deficiency plaguing the Mormon community of FLDS followers. Tarby said the only way to control the spread of the inherited disease is to ban marriage among blood relatives; inbreeding is the primary culprit.

Otherwise, the most city, state, and local leaders can do is spread awareness about the ultra rare condition.

[Featured Image by George Frey/Getty Images]