Confirmed again — now in France and Japan

Welcome

Your diagnostic journey is over. You finally have a genetic diagnosis for your RP. Let's proceed on the journey for potential future solutions!

This newsletter discusses only two subjects:

What is new in RNU4-2 and RNU6 RP — new papers, new families, new laboratory findings and potential therapies.

What is new in gene-agnostic treatments — treatments that could help anyone losing sight from an inherited retinal disease, whatever gene caused it.

We follow both subjects from the laboratory bench to the clinic. The earliest lab work — often years from any clinic — has its own section, Preclinical, clearly marked so a mouse study is never mistaken for a treatment.

If you want background on the gene, what it does and how it causes RP, go to cure46.org.

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RNU4-2 & RNU6 News

Confirmed again — now in France and Japan

The discovery this Foundation was built on keeps getting stronger. Two more research teams, each working on their own patients with their own methods, have independently reached the same answer: changes in RNU4-2 and RNU6 cause retinitis pigmentosa.

This is the most important kind of news a recent discovery can get. When one team reports a finding, it is a claim. When separate teams in different countries reach the same result, it becomes established science.

France. Doctors at the Quinze-Vingts National Ophthalmology Hospital in Paris screened a large group of families with dominant RP and found RNU4-2 and RNU6 changes in eight of them — about 2% of the families in their group whose genetic cause is known. One detail stood out: in these French families the mutation was passed down from a parent, while in the original discovery many patients were de novo, mutations that appeared for the first time in the affected person. Nobody yet knows why. (This French report is still a preprint — under peer review, not yet formally published — so its numbers could change.)

Japan. A genetics team in Tokyo (Nakano and colleagues published in iScience in August 2026) re-examined the DNA of 1,578 people whose inherited conditions had never been explained. One of them carried the very same RNU4-2 change the original study had already linked to RP. Exactly as that predicted, this person had retinitis pigmentosa — and no neurodevelopmental disorder — a patient on the other side of the world matching the discovery down to the single letter.

And finding it is getting cheaper. The Japan team's main goal was a practical one. Standard genetic tests read mainly the protein-coding parts of DNA and skip right over genes like RNU4-2 and RNU6 — a big reason so many families were told their result was "negative." Catching these changes has usually meant sequencing a person's whole genome, which is slower and costs more. The Tokyo group instead added a small set of detectors for 50 small-RNA genes (RNU4-2 and the RNU6 genes among them) onto an ordinary exome test. It found the changes reliably and added only about $7 to a roughly $200 test — far below the ~$400 for a whole genome.

This is a research method, not yet a test you can order from your doctor. But it points clearly to where testing is heading: cheaper, and far more likely to look in the right place. If your own genetic test once came back "negative," and you know you have RNU4-2 or RNU6 RP it is worth asking your genetic counselor whether re-testing with an up-to-date method makes sense. A written report from a clinical genetics lab is essential if you will ever participate in research or a clinical trial.

Read more: the science behind RNU4-2 and RNU6 is explained at cure46.org.

Sources: Audo, Zeitz et al. (Quinze-Vingts, Paris), preprint under review; Nakano Y, et al. iScience 2026;29:116814.

Gene-agnostic treatments: which ones could apply to you

Most gene therapies fix one specific gene. If and when that approach works it will likely never reach patients with very rare types of RP. The economics do not permit it.

Gene-agnostic treatments aim to help people with retinal degeneration regardless of the responsible gene. For a community our size, this is not a side story. It is probably an important stop on the main road.

The right question is not which technology is furthest along. It is how much of your retina is still functioning. That determines which of these could ever apply to you.

If your photoreceptors still work: protect them

NPI-001 (NACA) — Nacuity Pharmaceuticals. An antioxidant tablet, taken by mouth. It does not fix a gene. It tries to reduce the stress that damages retinal cells, and so slow the loss.

In a Phase 1/2 trial in Australia, 49 people took the tablet or a placebo twice a day for two years. Photoreceptor loss was slowed by more than 50%. The drug was well tolerated. (The part of this result that did not hold up — the retinal-sensitivity measure — is explained in the Epilogue.)

A larger Phase 3 trial is underway currently.

How to read this: encouraging, early, unproven but exciting. Let's keep a close eye on this!

SPVN20 — SparingVision (France). Cones are the photoreceptors you use to read and to recognize a face. This therapy aims to keep them working, whatever gene caused the disease.

The first patient has been dosed in a Phase 1/2 trial (NYRVANA) in Belgium. It will expand to France and Ireland.

How to read this: the earliest stage of anything in the clinic here. The first patient being treated is a starting line, not a result.

If your photoreceptors are mostly gone: replace or bypass them

MCO-010 — Nanoscope Therapeutics. In advanced RP, the light-detecting cells may be dead, but other retinal cells survive. This one-time injection is designed to make those surviving cells sense light themselves. A genetic diagnosis is not needed as this could work for all patients.

Three-year results — from the RESTORE trial, reported at a major retina conference in mid-2026 — showed patients with severe vision loss holding roughly three lines of vision improvement, with a good safety record and no treatment-related serious side effects. Notably, the benefit did not depend on which gene caused the disease: it held across the 15 different genetic causes represented in the study. That is exactly what "gene-agnostic" is meant to mean. An application to the FDA is underway.

How to read this: the furthest along of anything here, and closest to a decision by regulators. It is aimed at people with severe vision loss — not people in early RP. (MCO-010 is delivered by AAV which is a virus — see the Epilogue on why that matters for your future options.)

DSP-3077 — Sumitomo Pharma, Japan. A different idea: transplanting sheets of retinal tissue to replace cells that have been lost. In March 2026 the FDA granted it Orphan Drug Designation, a status that encourages companies to develop rare disease treatments. It is in a Phase 1/2 trial.

How to read this: Orphan Drug Designation is not an approval. It says nothing about whether the treatment works.

A broader approach

OCU400 — Ocugen. Rather than replacing one broken gene, this therapy aims to improve how retinal cells function generally.

In March 2026 the company finished enrolling 140 patients, including children aged three and up, in a Phase 3 trial. Results are expected in early 2027.

How to read this: finishing enrollment in a Phase 3 trial is a real milestone. It is not evidence the therapy works. That comes in 2027, or it does not.

Preclinical

What this section is: "Preclinical" means research done before any testing in people — in cells, in donated tissue, or in animals. It is where nearly every therapy begins. We include a few short items each issue so you can see what may be coming years down the road, with one honest caveat we will repeat every time: most preclinical findings never become treatments, and the ones that do take years to get there. Promising in a dish or a mouse is not the same as proven in a person.

Lab-grown human cone cells restored a basic visual response in blind mice. Researchers turned human stem cells into cone photoreceptors — the cells that handle detail and color vision — and transplanted them into mouse models whose own photoreceptors were essentially gone (end-stage degeneration). The transplanted human cones survived, connected into the existing retina, and responded to light across a realistic range of brightness. The treated mice also began showing a reflexive head-tracking response to moving patterns, a basic sign that visual signals were reaching the brain.

Why it is here: this approach replaces the missing cell itself rather than correcting any one gene, so in principle it would not matter whether the degeneration traces to RNU4-2, RNU6, or another cause. It is aimed at advanced disease, after photoreceptors have already been lost.

How to read this: this was done in mice, not people, and a head-turning reflex in a mouse is a long way from restored sight in a human. There is no human trial of this specific cell-transplant approach yet. We are flagging it as a direction worth watching — not a therapy on the horizon.

Sources: primary study — Procyk CA, et al.; Pearson RA, senior author. Stem Cells 2026;44(7):sxag023. Reviewed in Eye (2026), "Photoreceptor replacement: a disease-agnostic approach for the treatment of advanced retinal degeneration."

Epilogue — Three things worth repeating

1. This is not ReNU syndrome

RNU4-2 is one gene. Changes at certain positions in this gene will cause ReNU syndrome while changes at different positions cause retinitis pigmentosa. The two were found in separate studies, in separate groups of patients. Both the French and the Japanese teams confirmed this again: their RP patients' changes sat outside the ReNU region, and none had features of the neurodevelopmental condition.

Same gene. Different position. Different disease.

Your genetic report lists the exact change you carry. A genetic counselor can tell you which region it falls in. If a report has frightened you, that is the person to bring it to.

Looking for ReNU syndrome itself? That community is at renusyndrome.org.

2. "Statistically significant" is not the same as "matters to you"

When you read about a trial, you will meet two very different questions. It is easy to mix them up, and companies sometimes blur the line.

First question: is the result real, or could it be chance? Scientists answer this with statistical significance. "Statistically significant" means the difference is unlikely to be a fluke. "Not statistically significant" means it failed the test.

Second question: is the result big enough to matter to your life? Statistics do not answer this one. A treatment can slow vision loss by an amount that is statistically rock-solid and yet so small you would never notice it in daily life. That is a result that is real but not meaningful to you. With a big enough trial, even a difference too tiny to feel can come back "highly significant."

The reverse happens too: an early study might show a large, life-changing-looking effect that is not yet statistically solid, simply because too few people were tested.

So always ask both: Is it real? And is it big enough to change my day? A treatment worth having must pass both tests — not just one.

3. Why you may only get one shot at an AAV therapy

Several of the treatments we cover — including the gene-agnostic ones furthest along, like MCO-010 and SPVN20 — are delivered by a harmless virus called AAV, which carries the therapy into your eye.

Here is the catch. The first time your body meets AAV, your immune system can learn to recognize it. If that happens, a second AAV-based treatment later may not work, because your body clears the virus before it can deliver its cargo.

Why this matters for us specifically: a gene-agnostic AAV treatment — one for anyone with RP — may become available before a treatment aimed specifically at RNU4-2 or RNU6. Taking the first could reduce your ability to benefit from the second.

This is not a reason to refuse anything. It is a reason, before any AAV therapy, to ask your doctor how it could affect your future options — and whether timing, or treating one eye at a time, changes the picture for you.

This newsletter is for information only. It is not medical advice. Speak with your physician, genetic counselor, or another qualified medical professional before making any medical decision, changing treatment, or joining a clinical trial.

Published by CURE4/6, a nonprofit research foundation. Questions or corrections: ajacob@cure46.org

Disclosure: CURE4/6's editor is a co-author of the original discovery these findings confirm.

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