The diagnosis · 7 min read

What is ADTKD-MUC1?

The rare genetic kidney disease John lives with, in plain language. What it is, how it works, why it's not curable, and why a kidney transplant is the only real path forward.

If you searched for John's diagnosis after reading a news story, you probably ran into a wall of acronyms. ADTKD-MUC1. Autosomal Dominant Tubulointerstitial Kidney Disease, MUC1 type. Mucin-1. Tubular interstitium. The medical literature on this disease is dense and most of it is written for nephrologists, not families.

This page is for the rest of us. The friend who got a text saying "John needs a kidney." The neighbor who wants to understand what's actually happening to him. The would-be donor who needs to know what they'd be giving a kidney for.

Here's what ADTKD-MUC1 actually is, in language that doesn't require a medical degree.

The short version

ADTKD-MUC1 is a rare genetic kidney disease. It causes the kidneys to slowly fail over decades. There is no medication that stops it. There is no cure. The only effective treatment, once kidney function falls far enough, is dialysis or a kidney transplant.

John was born with the mutation that causes it. He inherited it from a parent who also had it. His kidneys worked fine for years, then started declining gradually, then declined to the point where doctors put him on the transplant list in the fall of 2025.

That's the whole story in one paragraph. Now let's break down what each part actually means.

Breaking down the name

The name "Autosomal Dominant Tubulointerstitial Kidney Disease, MUC1 type" is doing a lot of work. Each piece tells you something specific.

Autosomal Dominant

It's inherited from one parent. You only need one copy of the mutated gene to develop the disease. If a parent has it, each of their children has a 50% chance of inheriting it. It's not gender-linked — sons and daughters are equally likely to inherit it.

Tubulointerstitial

This describes where the damage happens inside the kidney. Kidneys are made of filtering units called nephrons. ADTKD damages the tubular part of those nephrons (the tubes that process filtered fluid) and the interstitial tissue around them (the structural matrix). This is different from kidney diseases that damage the filters themselves (called glomerular diseases).

Kidney Disease

Self-explanatory. The kidneys progressively lose function over many years.

MUC1 type

There are several subtypes of ADTKD, each caused by a mutation in a different gene. MUC1 is the gene that codes for a protein called mucin-1. In ADTKD-MUC1, that gene has a specific mutation that produces a misfolded version of the protein. The misfolded protein accumulates inside the kidney's tubular cells and damages them slowly over time.

What's actually going wrong inside the kidney

Imagine the kidney as an enormous, complex filtering system with millions of tiny tubes. In a healthy person, those tubes process about 50 gallons of fluid every day, reabsorbing what the body needs and excreting what it doesn't.

In someone with ADTKD-MUC1, the cells lining those tubes have a manufacturing defect. They keep producing a defective version of the mucin-1 protein. That defective protein gets stuck inside the cells instead of being secreted normally. It accumulates. It triggers stress responses. Slowly, the cells start to die.

As tubular cells die, the surrounding tissue scars. As more tissue scars, the kidney's filtering capacity drops. As filtering capacity drops, waste products build up in the bloodstream. Eventually the kidneys can no longer keep up, and the patient needs dialysis or a transplant to stay alive.

This process takes decades. Most people with ADTKD-MUC1 reach kidney failure somewhere between their 30s and their 60s.

Why it's hard to diagnose

ADTKD-MUC1 is notoriously difficult to identify, for a few reasons.

It doesn't show up well in standard blood and urine tests. Many genetic kidney diseases produce telltale markers — protein in the urine, blood in the urine, abnormal cells under a microscope. ADTKD-MUC1 doesn't. Routine bloodwork usually just shows declining kidney function (rising creatinine), which can mean a thousand different things.

Kidney biopsies are often inconclusive. The biopsy may show scarring and tubular damage, but those findings are nonspecific. They can result from many different diseases.

The MUC1 gene mutation is hard to detect with standard genetic testing. The disease-causing mutation is a single inserted base pair in a highly repetitive region of the gene. Most genetic sequencing technologies skip over repetitive regions because they're hard to read accurately. A specific, specialized test is required to find this particular mutation.

For these reasons, ADTKD-MUC1 was nearly invisible to medicine until 2013, when researchers finally identified the genetic mutation. Before then, many people with this disease were given the catch-all label of "kidney failure of unknown cause." Some families had three or four generations of unexplained kidney disease before the actual cause was found.

What can be done about it

There is no medication that stops or slows ADTKD-MUC1. Drugs that protect kidneys in other diseases (like ACE inhibitors used in diabetic kidney disease) have not been shown to meaningfully change the disease's progression.

What helps:

• Careful management of blood pressure to reduce strain on the failing kidneys.
• Dietary adjustments — lower sodium, careful protein intake, sometimes limited potassium and phosphorus.
• Monitoring kidney function regularly so the patient and care team can plan ahead.
• Avoiding nephrotoxic medications — drugs like NSAIDs that are hard on healthy kidneys are even harder on failing ones.

These measures buy time. They don't stop the disease.

When kidney function falls below about 15-20% of normal, the patient typically faces two options: dialysis (a machine that filters the blood several times a week, indefinitely) or kidney transplant.

Why transplant is the better path

Dialysis keeps people alive but it's grueling. Most patients on dialysis spend 12 to 15 hours a week hooked up to machines. They have dietary restrictions that exclude many foods most people eat without thinking. They have fatigue, often deep and chronic. The five-year survival rate on dialysis is significantly lower than for transplant recipients.

A kidney transplant, by contrast, restores most of normal life. With a successful transplant:

• The patient is no longer tethered to a dialysis schedule.
• Dietary restrictions ease dramatically.
• Energy returns. Most recipients describe it as life-changing.
• The new kidney, well-cared-for, can function for 15-20 years from a living donor.
• Anti-rejection medications are required for life, but they are well-tolerated by most patients.

For an active, working person in their prime — a husband, a father, a teacher who plays guitar at church on Sunday mornings — transplant is the option that allows life to continue more or less normally.

Why John is in paired donation

ADTKD-MUC1 affects the kidneys but doesn't change John's blood type or his immune system. His situation in the transplant program is the same as anyone else's: he needs a donor whose blood type and tissue antigens are compatible with his.

His lifelong friend Kraig Mewbourne volunteered first. Kraig's blood type and immune profile didn't match John's directly. Paired donation exists precisely for this situation. Kraig can still donate — to a stranger somewhere in the country — and in exchange, a stranger's donor whose profile matches John's will give him his kidney. It's an exchange. Both transplants happen. Both lives change.

Anyone healthy enough to be a living donor can help John, regardless of blood type, through this program. You don't have to share his genetics, his blood type, or anything else specific. You just have to be willing to be tested.

One thing about the inheritance

Because ADTKD-MUC1 is autosomal dominant, John's two daughters each have a 50% chance of having inherited it from him. This is part of the reason John's transplant matters beyond his own life: he wants to be there for his daughters when they're tested as adults and when they navigate their own potential kidney futures.

Research into ADTKD-MUC1 has accelerated since the gene was identified in 2013. There are now early-stage drug candidates being studied that may someday slow the disease. None of them are ready for clinical use yet. But the field is moving.

John needs to make it to that future. A new kidney is how he gets there.