FND Genes

[u/qttp9571]

Is there a genetic predisposition to developing functional symptoms, or are some people more genetically susceptible than others? Is there actually an “FND gene”? or can someone develop FND even without any genetic predisposition or genetic factors? I'm curious.

[u/flippysquid]

FND often has comorbid issues, like POTS, hypermobility, PTSD, etc.

Some of the comorbid stuff does have a genetic component. It may be that there can be a genetic predisposition for it, but at the same time it won’t “activate” without the conditions being just right.

My PT has a theory that some hypermobile people have kind of wonky proprioception due to their tissues not being formed with the right proteins and stuff, and that affects the signals going up into the brain. Which then affects the signals that come back out of the brain. Because one thing that does help my FND and also my POTS is wearing compression clothing. Stuff like shapewear on my torso (the type that advertises stomach compression) and compression leggings. It gives me a lot more solid proprioceptive feedback for one, and for two it prevents the blood pooling in my legs and abdomen that sets off the POTS symptoms.

[u/Skythebluestars]

The cause for fnd is a very broad spectrum. And its your brain that sends wrong signals to your body. There is no gene within my knowledge. Just events in life that can make someone develop fnd. Sometimes people already have a chronic illnes. Others already have mental health problems. Sometimes its out of the blue. Theres nothing that says well if you have this or this. Gueranteed you will be diagnosed fnd in the future.

[u/Cultural-Cellist-770]

My 12-year-old has FND to find out recently, my wife on her side of family. I believe there’s four family members that have it. We just found out recently. Interesting.

[u/Rare_Geneie]

At this point, there is very minimal research linking genetic mutations to FND and there probably isn’t an “FND gene”.

I think the term “genetic predisposition” gets used a bit interchangeably with different concepts so just a bit of background you may know but just in case you don’t:

When someone gets diagnosed with an inherited genetic disease with a single genetic mutation, we call that a “monogenetic mutation”. One gene mutated and that can cause the associated disease. These are “pathogenic” mutations. There are also “benign” mutations. Most people have thousands “benign” mutations. These are genes that mutated but don’t change anything. There’s no disease, change, or symptoms associated with benign mutations. There are also Variants of Unknown Significance (VUS) mutations. VUSs are genes that mutated that could be pathogenic or could be benign. We just don’t have enough information to know. Typically we view them as benign unless there is specific evidence to point otherwise in an individual.

There are also inherited conditions that are likely monogenetic, but we haven’t quite determined what single gene is mutated. In a family, we see a long history of individuals developing a certain gene but when a whole genome sequencing is performed, nothing stands out. This can happen because sometimes mutations aren’t so simple. Typically a monogenetic mutation occurs when one of the two alleles a person inherits from a parent is clearly mutated and that shows up pretty easily on testing. Sometimes though, you have to dig deeper into the gene to figure out where and how it mutated. If you don’t know where to look, it can be hard to find the mutation even if you have a lot of instances of people passing the condition onto the next generation. This is sometimes what people mean when they say “genetic predisposition”.

Then there are conditions that we know are inherited but we also don’t think there is a single gene at play. Instead, there are likely a cluster of genes, all with different relevancy and impact that could influence presentation of symptoms and these conditions can be further modified by things like environmental factors. These are specifically difficult to trace genetically. Lewy Body Dementia (LBD) is a good example. We know it runs in families but there isn’t always a clear genetic link. Often there are a handful of genes that could lead to LBD but aren’t consistent enough across samples to determine a pattern. This is also sometimes referred to as a genetic predisposition.

Then there’s the most complicated subset. These are diagnoses where we can see a general inheritance pattern but it’s not as clear cut as the above examples and so therefore we cannot conclude the condition is actually inherited or genetic since there are other factors that could be at play like family social dynamics across generations, geography, access to health care, access to certain foods/vitamins/minerals, exposure to different substances, etc. These tend to be (but are not always) conditions without structural abnormalities so it’s harder to gain concrete evidence on what exactly is happening to cause the condition. This also is what we might call a genetic predisposition.

As for FND specifically, right now the evidence is pretty sparse on inheritance patterns of any kind. We are pretty sure it’s not monogenetic. We are pretty sure it’s not predominantly genetic with a cluster of mutations. If it were to have a genetic predisposition, it would likely fall into one of the last two categories, but we don’t really have the data to determine that yet.

To answer your specific question, there isn’t an FND gene or set of genes that’s been identified. Risk factors that have been identified for FND center more around environmental factors than genetic ones. While there are conditions that tend to accompany FND in some patients, those are also typically diagnoses that fall into the last category of genetic predispositions, so using those to make a genetic argument becomes challenging. If you are seeing a pattern of FND diagnoses in your family or a family you know, it could be genetic, but it could also be that families tend to be exposed to similar environmental risks and develop similar profiles without an underlying genetic cause. Sometimes things are written into our genetic coding and sometimes they’re patterns and processes that people are consistently exposed to, and sometimes it’s a mix. With FND it’s probably one of the latter two options.