“Ultra-Rare” Genetic Disorder Discovered To Be 4,500 Times More Common Among Amish
Due to the unusual nature of the Amish population, they frequently serve as a source for medical discoveries, especially related to genetic research.
These can be discoveries on the “positive” side – such as the gene mutation in one Amish community which accounts for an over 10% longer lifespan, or one linked to lower levels of heart disease.
They can also be about negative health outcomes, such as increased risk of sudden cardiac death in Amish children.
It turns out that researchers have come across another one in the latter category: concerning an “ultra-rare” condition called complement factor I (CFI) deficiency.
This comes about from work done in tandem by Lancaster County’s Clinic for Special Children and Children’s Hospital of Philadelphia.
CFI deficiency is described as “significantly more prevalent in individuals of Old Order Amish ancestry” by reporting at WITF.
But just what is CFI deficiency and what does it cause? According to WITF:
“CFI deficiency… is a protein in our bodies that is a really critical component of our immune system called the complement system,” explained Dr. Laura Poskitt, Medical Director of the Clinic for Special Children.
“The complement system plays a really important role in our early immune response… When you don’t have CFI, you can get over-activation and inflammation in the immune system. This can cause brain injury, spinal cord inflammation, and can be really disabling.”
How much more prevalent is it among the Amish? It’s described as “extremely rare in the general population” – but 4,500 times more likely to appear in people who have Old Order Amish ancestry.
I don’t know how many individuals that translates to, but that is undoubtedly a huge difference.
And note that we are talking about “Old Order Amish ancestry”, which concerns a significantly larger group of people than just the current population of 400,000-some Old Order Amish.
The Founder Effect
The dynamics of what causes this is frequently misunderstood, as Poskitt explains:
Dr. Poskitt attributed this to a genetic phenomenon known as the “founder effect.”
“Out of the about 400,000 Amish individuals living in the U.S., they descended from about 80 to 100 individuals who started that gene pool,” she said. “Because of that limited gene pool, some disorders, like CFI deficiency, are much more common.”
This is something different than the idea of marriage between close relatives, which tends to capture the popular imagination:
Dr. Poskitt stressed that this is not due to close familial marriages, as sometimes assumed, but rather the historical genetics of the community.
She also compared it to other genetic conditions, noting, “Cystic fibrosis is common in people of Western European heritage, but virtually non-existent in the Amish. Other disorders, like CFI deficiency, are more common because of the small founder population.”
The report notes that early identification and intervention are key to preventing serious complications. There are vaccinations and antibiotic treatment available for the afflicted.
And, as is often the case with medical research involving the Amish, there are potential benefits for the non-Amish community:
The findings could help clinicians worldwide better recognize and manage this disorder, particularly in communities where it occurs more frequently, and ultimately establish standards of care to protect patients from severe complications.
It’s an interesting note: “particularly in communities where it occurs more frequently”.
That indicates to me that even though this may be much, much more common among Amish when compared to the general non-Amish population, that there still may exist communities of people where this disorder presents itself more frequently than “the norm”.
And those people could be half a world away, yet the research done in traditional Amish communities could end up benefiting them too.
There is a much longer discussion about this story by WITF, which you can listen to here:
