Mark G. Hubers — Just an Engineer with USH
Someone recently asked whether Germany has the most people with Usher syndrome (USH). I didn’t know the answer. And I realized I’ve been deep in treatment pipelines and clinical trials for months now, but I’ve never actually looked at the basic question: where are we? How many of us are there? Who gets this?
I’ve had bits and pieces of this data floating around in my head for a while; carrier rates, the Jewish connection, a few numbers here and there. I always thought it would make a good topic to pull together. So I finally did. And honestly, even I was surprised by what came back.
Since I first published this essay, readers from India, the UK, South Africa, and across the US have sent me data I didn’t have. Researchers I’ve never met. Parents who tracked down studies I missed. That’s what happens when you say “I want to hear it” and mean it. This version includes everything I’ve learned since.
Fair warning, I am just an engineer with Usher syndrome, so this is a data dig, not a research paper. If anyone has better data or corrections, I want to hear it.
Data on how common USH is (prevalence) is really hard to come by. Most countries don’t track it. A huge number of people are undiagnosed or misdiagnosed. The studies that exist are small, regional, and some are decades old. So these are the best numbers I could find as of April 2026, not the final word. If anything, the real numbers are probably higher.
How Many of Us Are There?
There are somewhere between 400,000 and 720,000 people living with Usher syndrome worldwide. That’s a massive range, and the reason is simple. Most people with USH are never properly diagnosed.
A 2025 genomic study (Redfield et al.) came at it differently. Instead of counting diagnosed patients, they looked at how often USH gene variants actually appear in human DNA. Their number: 721,769. That includes everyone; diagnosed, undiagnosed, people who have no idea what’s coming.
About 12,000 babies are born with USH every year worldwide. Roughly 324 in the US.
And here’s the one that stopped me cold: 1 in 100 people carry a pathogenic USH variant, meaning a broken copy of a USH gene that can cause the condition. They’ll never know unless they have a child with another carrier. Let that sit for a second. One in a hundred people you pass on the street. About 80 million carriers worldwide.
So why aren’t there millions more of us? Because USH is recessive. Both parents have to carry a broken copy. The odds of two carriers finding each other: 1 in 100 times 1 in 100 = 1 in 10,000 couples. And even then, each child only has a 25% chance. Do the math: 1 in 10,000 times 1 in 4 = roughly 1 in 40,000. That’s close to the observed rate of about 1 in 29,000. The carriers are everywhere. The disease is rare because it takes two.
Think of it like a wiring defect. One in a hundred people are walking around with one bad wire. They’ll never know. The backup wire handles it fine. But if two people with the same faulty wire have a child who inherits both bad copies? No backup. That’s USH.
So Where Is USH Highest?
Country / Region USH Rate Notes Margarita Island, Venezuela ~76 per 100,000 Isolated community. 22x the global average. Sweden ~1 in 10,000 Highest documented national rate Germany ~1 in 16,000 2002 Heidelberg study India (Southern states) ~20 per 100,000 Hospital-based, not population-based. High consanguinity in South. USA ~1 in 25,000 ~30,400 people estimated Norway ~1 in 28,000 ~400 estimated undiagnosed Japan ~0.4 per 100,000 2021 study, called it a minimum Pakistan Not well studied MYO7A dominant (not USH2A). High consanguinity.
Sweden holds the highest documented national rate: 1 in 10,000. That might be because Sweden is better at tracking it, not because they have more of it. Hard to say.
Germany: 1 in 16,000 (from a 2002 Heidelberg study). So the claim about Germany being high is real. But Sweden’s rate is higher, and the US likely has more total people with USH just because of population size.
And then there’s Margarita Island, Venezuela. 76 per 100,000. I had to read that three times. A small, isolated community where one ancestor carried a mutation in a gene called MYO7A (one of the main USH1 genes) and everyone married locally for generations. The carriers didn’t spread out. They stayed, and the odds of two carriers having kids went way up. Twenty-two times the global average. That’s what recessive genetics does when carriers stay in one place.
When you zoom out to whole countries though, large mixed populations, the rates mostly level back out to around 1 in 25,000 to 1 in 40,000. That’s roughly what the carrier math predicts. The hot spots aren’t breaking the math. They’re showing what happens when carriers stop being random and start being neighbors.
And I want to be clear about something. If you’re from one of these communities, this is not why you have USH. These patterns built up over many generations when moving far from home wasn’t easy and marrying within the community was just how life worked. Today, consanguinity rates are dropping in most of the world. The mutations that concentrated over centuries are still there, but the pattern that concentrated them is fading. This is history, not blame.
How Old Are These Genes?
This is the part that changed how I think about USH.
The genes that cause Usher syndrome are not human genes. I mean, they’re in our DNA. But they didn’t start with us. Not even close.
USH2A, the gene that’s broken in me, has relatives in sea urchins. Sea urchins don’t have eyes. They don’t have ears. But 500 million years ago, the protein that USH2A makes was already doing something important enough that evolution kept it around. Every vertebrate since has carried a version of it.
MYO7A, the most common USH1 gene, works in fruit flies. The fly version is called “crinkled.” If you knock it out, the fly goes deaf. Its hearing organs detach. That means the hearing function of this gene is at least 600 million years old. Before vertebrates. Before anything had an ear the way we think of ears.
The genes are ancient. The mutations are recent.
The most common USH2A mutation in humans, a deletion called c.2299delG, has been traced to a single ancestor who lived in Europe about 5,000 to 7,000 years ago. One person. One mutation. Today it shows up in patients across 14 countries. You can literally trace one person’s DNA change spreading across a continent over thousands of years.
When What ~600 million years ago MYO7A ancestors working in invertebrate sensory systems ~500 million years ago USH2A structural role established before the vertebrate/sea urchin split ~5,000-7,000 years ago c.2299delG arises in Europe (Neolithic/Bronze Age) ~2,000-4,000 years ago Finnish CLRN1 mutation concentrates during isolation ~500-1,000 years ago PCDH15 R245X concentrates in Ashkenazi Jewish communities ~400 years ago USH1C mutation carried to the New World by French settlers 1858 Albrecht von Graefe first describes the condition clinically 1914 Charles Usher names the syndrome 1995 First USH gene (MYO7A) identified
We carry ancient genes with recent breaks. The machinery is half a billion years old. The damage is a few thousand years old at most.
The Ancestry Piece – This Is Where It Got Interesting
I went into this thinking USH was USH. Same disease everywhere. It is not.
USH is a collection of mutations that ended up causing the same thing. And certain mutations got concentrated in certain populations because of how humans migrated, married within their communities, and stayed put. Your ancestry isn’t just background info, it shapes which mutation you carry and which treatments might work for you.
Ashkenazi Jewish communities have elevated rates of both USH1 and USH3. One specific DNA change in a gene called PCDH15 (mutation R245X) has a carrier frequency of 1-2.5% depending on the population studied. To put that in perspective: if 1 in 100 is the general carrier rate, parts of the Ashkenazi population are running at 2.5 in 100. That changes the math fast.
In Finland, USH3 accounts for 40% of all USH cases. Everywhere else in the world it’s 2-5%. One mutation called “Finmajor” is responsible. Finland has a whole set of rare diseases that concentrated over centuries of geographic isolation; they call it the Finnish disease heritage.
In French-Acadian and Cajun populations, one single DNA change in the USH1C gene (c.216G>A) accounts for 90% of their USH1. It traces back to the families expelled from Nova Scotia in 1755. Southwest Louisiana today has the largest deaf-blind community in the United States because of it. Think about that. A forced migration 270 years ago is still showing up in people’s DNA.
For Europeans in general, the most common USH2 mutation worldwide is a specific deletion in the USH2A gene (c.2299delG). It accounts for about a third of USH2 cases across Germany, France, and European-Americans. If you have European ancestry and USH2, there’s a decent chance this one’s involved.
And in East Asia, a completely different mutation passed down from a common ancestor (a founder mutation) shows up in Chinese and Japanese populations that has never been found in Europeans. Different continent, different mutation, same disease.
In 2025, a large study from Pakistan found that MYO7A is the dominant USH gene there. Not USH2A. The exact opposite of Western populations. Pakistan has some of the highest consanguinity rates in the world, over 60% of marriages, and USH genetics there are just starting to be mapped. Same disease, completely different genetic path.
Founder Populations Most People Don’t Know About
Since the first version of this essay, I found data on populations that rarely make the USH conversation:
Indigenous South Africa. A single MYO7A mutation (c.6377delC) was found across three different ethnolinguistic groups: Xhosa, Zulu, and Sotho. All patients shared the same genetic fingerprint. One ancestor, before these groups diverged. That mutation is old. And here’s the problem: testing panels designed for European patients catch only 12.8% of indigenous African patients. Most African USH variants haven’t been catalogued yet.
North Africa and the Maghreb. Researchers in Tunisia, Algeria, Morocco, and Mauritania tested 450 deaf patients and found 211 different mutations. 36% had never been reported before. More than a third of the mutations were invisible to existing databases.
The Arabian Peninsula. A deep intronic CLRN1 mutation specific to the Arabian region causes severe USH3. It would be completely missed by standard genetic testing because it sits in a part of the DNA that most tests don’t even look at.
Non-Ashkenazi Jewish populations. Four distinct USH2A founder mutations that are different from the Ashkenazi variants. Different community, different mutations, same gene.
I’m Polish and Dutch heritage myself, and there’s no specific data for either population. But my USH2A mutations are consistent with the broader European pattern.
The Parts Nobody’s Talking About
Asia
Most of what I just covered is European, Jewish, and North American data. That’s not because USH doesn’t exist elsewhere. It’s because nobody’s looking.
Asia has over 4 billion people. India alone has 1.4 billion. China another 1.4 billion. Apply even a conservative USH rate to those numbers and you’re looking at potentially hundreds of thousands of people. Most of whom have never been genetically tested, never been properly diagnosed, and have no idea there’s a global community or clinical trials they might qualify for.
Since publishing this essay, I heard from an Usher syndrome ambassador in India. That conversation led me to dig deeper, and I found actual data. A study at the L V Prasad Eye Institute, one of the largest eye hospital networks in Southern India, found USH in 401 out of 2.5 million patients. That’s 2.6% of all their RP patients. The study covered hospitals in Telangana, Andhra Pradesh, Karnataka, and Odisha.
I need to be clear: those numbers are hospital-based, not population-based. They can’t be applied to all of India. India’s national family health survey shows consanguinity rates of 26-28% in the Southern states where this study was done. That’s more than double the national average of 10.8%. Northern India, where consanguinity is much lower, would likely look very different. Nobody has published those numbers yet.
Using the Redfield 2025 genomic data proportionally, India’s USH population is probably around 120,000 to 130,000 people. That would make India one of the largest USH populations in the world by sheer numbers. And almost none of them are in any registry.
The consanguinity connection is the same pattern we see everywhere else. In the general population, two strangers both carrying the same USH variant is a 1 in 10,000 chance. In a family that marries within itself, grandpa’s bad copy shows up on both sides. The matching problem disappears. It’s not different biology. It’s the same math with a smaller deck of cards.
China just screened millions of people for retinal disease, but nobody’s asking how many of those people have Usher syndrome specifically. Japan has at least some data: a 2021 nationwide study found a minimum rate of 0.4 per 100,000, but they called it a minimum because most cases go unreported. For most of South Asia and Southeast Asia, almost nothing exists in the published literature.
Native Americans
This is the gap that surprised me the most.
The published literature has exactly one documented Native American USH patient. A 2025 study from South Florida. 148 patients, diverse backgrounds. One American Indian or Alaska Native. Molecular testing was inconclusive.
One. In all the medical literature I could find.
But here’s what population genetics tells us: Native Americans experienced some of the most extreme founder bottlenecks in human history. Everyone descends from a small group that crossed the Bering land bridge about 15,000 years ago. All Native American mitochondrial DNA traces to just five founding maternal lineages. Five.
That’s the same kind of isolation event that concentrated USH in Finland, in the Ashkenazi community, in Acadian Louisiana. Different scale, same mechanism. If any of those five lineages carried a USH variant, drift could have amplified it in the founding population.
At the standard 1 in 29,000 rate, there should be about 235 Native Americans with USH in the United States. But over 96% of all hearing loss genetic studies are conducted on European or Asian subjects. Native Americans average 0.3 studies per year. The absence of evidence is not evidence of absence. Nobody’s looked.
Africa
Testing panels designed for European patients miss most African USH variants. Only 12.8% of indigenous African patients get a conclusive genetic diagnosis, compared to 41.1% for Caucasian patients. The testing exists. The variants in the tests don’t match the variants in the patients.
Dogs, Cats, and the Question Nobody Asks
This might be the most surprising part of this whole essay.
A community member asked me: “Why don’t wild animals seem to have diseases like USH?” The answer changed how I think about why this condition exists.
They do. You just never see them. Because they’re dead.
In the wild, a deaf animal can’t hear a predator. A blind animal can’t find food. An animal losing both at once is gone before it ever reproduces. Natural selection is brutally efficient on sensory loss. The affected animals are removed.
But the carriers, the ones with one good copy and one bad copy, are perfectly fine. Invisible. Natural selection can’t see a recessive carrier. The bad copy hides behind the good one and gets passed along quietly, generation after generation.
That’s why USH persists. Not because it’s an advantage. Not because it’s neutral. Because the carriers are invisible to selection, and there are 80 million of them.
Now look at what happens when you take natural selection out of the equation.
Dogs. Progressive retinal atrophy (the dog version of RP) is autosomal recessive in most breeds. It affects dozens of breeds including Labrador Retrievers, Cocker Spaniels, and Golden Retrievers. Hereditary deafness is documented in over 80 dog breeds. Dalmatians are the most famous, but it runs through Australian Shepherds, English Setters, and many more.
Cats. White cats with blue eyes: 65-85% are deaf in one or both ears. Congenital, sensorineural, linked to the same melanocyte biology that gives them their coat color.
Lab mice. The “shaker-1” mouse has a MYO7A mutation. The same gene as USH1B in humans. The mouse is born deaf with balance problems. It bobs its head and runs in circles. That behavior is how researchers found it. In the wild, that mouse would have been eaten in its first week. In a lab, it lives long enough to teach us about our own disease.
In 2023, researchers at Oregon Health and Science University created the first USH1B primate model using gene editing (CRISPR). A rhesus macaque with MYO7A mutations that mirror the human disease. That animal exists because we can now study USH in a species close enough to us that the results might actually translate to treatment.
The genes that cause USH are half a billion years old. Every species that has ears and eyes has some version of them. We didn’t get a new disease. We got old genes in a world where the rules changed. Humans broke the equation. Medicine and society removed the selective pressure. People with USH live full lives, have children, build careers. The condition persists not because something went wrong with evolution, but because we outgrew the part of evolution that would have stopped it.
The ICD-10 Milestone (and Its Limits)
As of October 2025, Usher syndrome has its own ICD-10-CM codes (Q99.811 through Q99.819). This matters for tracking. For the first time, doctors can code specifically for USH Type 1, Type 2, or Type 3. Before this, USH was lumped into generic categories. Diagnosis codes drive insurance coverage, research funding, and prevalence tracking.
But here’s the catch: there are no sub-codes for gene types. The system can count “how many Usher Type 2” but it cannot distinguish USH2A from USH2C. That matters because treatments are becoming gene-specific. Knowing there are 29,000 Type 2 patients in the US doesn’t help if you need to know how many of them carry the specific mutation your drug targets.
Gene-level tracking still requires registries like My Retina Tracker and Rare-X. Medical billing codes got us to the type level. The gene level is still a manual effort.
Male vs Female
There is no difference. USH is autosomal recessive, meaning it lives on one of the regular chromosomes, not on X or Y. Gender has nothing to do with it. Males and females are equally likely to carry it, have it, or pass it on.
The Type Breakdown
Type % of All USH US Patients (est.) Notes USH2 ~60% ~29,100 Most common. That’s where I am. USH1 ~25-35% ~2,800 Usually more severe, earlier onset USH3 2-5% ~66 Jumps to 40% in Finland and Ashkenazi Jewish communities USH4 Extremely rare – Recently recognized (ARSG gene). Still being studied.
Those US numbers come from Redfield et al. 2025, the same DNA-based study that estimated 721,769 worldwide. Look at USH3. 66 people in the entire United States. And there’s now a fourth type that’s barely been studied at all.
The Numbers That Hit Hardest
10% of all children born with hearing loss in both ears (bilateral) have Usher syndrome. Most are never tested for it.
50% of all deaf-blind people have Usher syndrome.
A 2025 study from South Florida looked at 148 USH patients from diverse backgrounds. White patients were significantly more likely to get a conclusive genetic diagnosis than non-white patients. The testing exists. It just doesn’t reach everyone equally.
India alone may have 120,000 to 130,000 people with USH. Almost none are in any registry or study.
Native Americans have virtually zero representation in USH genetic research. There should be about 235 people with USH among 6.8 million Native Americans. Nobody has looked.
The genes that cause USH are 500 to 600 million years old. Your dog might carry a version of the same broken gene. The shaker-1 mouse was named for the head-bobbing caused by the same gene that causes USH1B in humans.
Every USH family carries a piece of population genetics history in their DNA. The Acadian mutation traces a forced migration from 1755. The Finnish mutation maps centuries of isolation. The Ashkenazi mutations reflect centuries of marrying within close-knit Central and Eastern European Jewish communities. The South African mutation predates the divergence of the Xhosa, Zulu, and Sotho peoples. The European c.2299delG traces to one person who lived 5,000 to 7,000 years ago.
We’re not just patients. We’re walking history.
It was a good question and the numbers were too interesting not to share. Since publishing the first version, readers from four continents have sent me data, corrections, and studies I missed. That’s exactly what I hoped would happen.
If you have corrections, better data, or know of studies I missed, I want to hear it. This stuff should be compiled somewhere accessible, not buried in journals nobody reads.
~Mark
Sources: Redfield et al. 2025 (Am J Med Genet), Kimberling et al. 2010, Boughman et al. 1983, Grøndahl 1987 (Norway), Espinós et al. 1998 (Margarita Island), Joensuu et al. 2001 (Finland), D’Esposito et al. 2025 (Genes), Cromar et al. 2025 (Human Genomics), Nishiguchi et al. 2021 (Commun Biol), Pakistani IRD Cohort 2025 (npj Genomic Medicine), Parameswarappa et al. 2023 (LVPEI/APEDS), NFHS-5 2019-21 (India consanguinity data), Kannabiran et al. 2022 (Frontiers Genet), Aller et al. 2010 (Eur J Hum Genet), Dreyer et al. 2001 (Am J Hum Genet), Ebermann et al. 2007 (Hum Genet), Ebstein et al. 2015 (ARVO), Toms et al. 2015 (IOVS – South Africa), Slimani et al. 2025 (Maghreb), Moreno-Pelayo 2023 (Arabian CLRN1), Ben-Arie et al. 2000 (Drosophila MYO7A/crinkled), Strain 2011 (hereditary deafness in dogs), OHSU 2023 (CRISPR primate USH1B model), Achberger et al. 2019 (Ush2a zebrafish). Full citation list: essays/count/fact-check.md
Mark,let me say for all the quiet ones nurished by all your courageous work, we hear/see:appreciate all your work! Keep on going!! TD
Thank you for pulling all of this together and sharing in accessible language.
There is another group - perhaps vanishingly small - of people like me with RP and hearing loss who have no as yet identified mutations known to cause Usher Syndrome. I have my DNA retested regularly as more variants are identified but still no matches.
I was diagnosed with RP at age 35 and still have good central vision. Hearing loss started soon after - so relatively late onset for both. One older brother had hearing loss since his teens and was diagnosed with RP when he was 40. No other affected family members or ancestors that we know of.
The most recent analysis of my whole genome sequencing identified a mutation in RIMS1 which they are calling a “gene of uncertain significance” that may be associated with Usher type symptoms. Or, it could be that my hearing loss and RP are unrelated….
The upshot for me is that the wonderful developments in gene-specific treatments are probably not relevant to my case, but the gene-agnostic ones may hold some promise.