Every day matters for Muk

Help us save Muk!

Muk is five years old and has Sanfilippo, a severe form of childhood dementia. The disease is progressive and irreversible: every day, she may lose skills that will never return.

An important step

FAYUVI is approved. Now we keep going for Muk.

The US FDA has approved FAYUVI, formerly UX111, for Sanfilippo type A. This brings new hope.

€1,065,216raised for Muk

Donate for Muk

We do not yet know the cost of Muk’s treatment and everything around it. That is why we are continuing to raise funds for treatment, medical preparation, travel and accommodation.

Every donation still matters.

Read Muk’s story
Follow Muk’s journey to America on Instagram
Muk lacht stralend buiten

Where we stand

Step by step towards treatment in America

We are in contact with a treatment centre in America and are working on Muk’s medical preparation.

  1. Contact in America

    We are discussing with the treatment centre what is needed to assess Muk.

  2. Medical records

    We are gathering Muk’s complete medical records for that assessment.

  3. An important blood test

    Muk needs to be tested for antibodies to AAV9, the virus used to deliver the gene therapy.

Follow Muk’s journey to America

On Instagram, we share the latest steps, new developments and personal updates.

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This is Muk
Welcome to Stichting Muk tegen Kinderdementie

Muk’s story

This is Muk. Our cheerful, strong-willed and sensitive little girl. She is full of imagination, love and joy, and touches so many hearts. Yet Muk lives with something you cannot see at first: she has been diagnosed with Sanfilippo, a rare and serious condition also known as childhood dementia.

Muk’s prognosis is heartbreaking: children with this disease have a life expectancy of 12 to 15 years. If she reaches that age, it means she will use a wheelchair towards the end of her life and will be able to do very little, or nothing at all, shortly before she dies. We cannot bear that thought.

There is hope. The FDA approved FAYUVI, formerly UX111, on 17 September 2026. It is the first approved treatment for Sanfilippo type A and may slow the disease and help preserve important abilities for longer.

Muk’s Story Muk’s Story
The Treatment The Treatment

Why every day matters

Childhood dementia gradually takes away the things Muk can still do

Sanfilippo is a rare, inherited disease. Muk’s body is missing an enzyme needed to break down certain waste substances. These substances build up in her brain and cause increasing damage to brain cells.

Speaking and understanding

Muk may lose words and communication skills. This makes it increasingly difficult to express what she feels, wants or needs.

Walking and moving

Her balance and movement skills may decline. This can make walking, playing and moving independently increasingly difficult.

Eating and daily life

Things she can still do naturally may eventually require more and more help and daily care.

Memories and recognition

The disease may affect her memories and make it increasingly difficult to recognise the people she loves.

Muk zit binnen en kijkt opzij

The disease continues to progress. What Muk loses to the disease usually does not return. That is why every day matters for her.

What we know about the treatment

A treatment that brings new hope

FAYUVI, formerly UX111, is a one-time gene therapy given through an infusion. It helps the body produce the enzyme missing in Sanfilippo type A.

In research, treated children maintained important developmental skills better than comparable children without treatment. Doctors assess whether FAYUVI is suitable for each child.

Read about FAYUVI (UX111)

Help make treatment accessible for Muk

So much has already been given. The total cost for Muk is not yet known. That is why we are continuing to raise funds, so that money is as little of a barrier as possible if treatment becomes possible.

Donate for Muk

Choose your contribution

Give Muk a chance of treatment

€25 is suggested, but every amount helps. You can also choose your own amount.

Pay securely through Rabo Smart Pay. iDEAL, Bancontact, credit card, Apple Pay and PayPal. After choosing your amount, enter your name and email address. We use these details to process and confirm your donation and send a one-time thank-you message. We only display your first name among recent donations if you choose this at checkout.

Donating on behalf of a business?

For a business donation or a large amount, a bank transfer is often the simplest option. Would you like to discuss your donation or the details needed for your records? Email steun@stichtingmuk.nl.

Prefer a bank transfer?

Transfer your contribution directly to:

Frequently asked questions

What is Sanfilippo, and which type does Muk have?

Sanfilippo is a rare, inherited metabolic disease also known as childhood dementia. A missing enzyme prevents the body from properly breaking down certain waste substances. These substances build up in the brain and elsewhere. Muk has type A, an aggressive form of the disease.

What is FAYUVI, formerly UX111, and what could treatment mean for Muk?

FAYUVI, formerly UX111, is a one-time gene therapy given through an infusion. It is intended to help the body produce the enzyme missing in Sanfilippo type A. The aim is to reduce the harmful build-up of substances and slow further decline. Research data give hope that treated children may retain important skills for longer. FAYUVI is FDA-approved. Whether and when Muk can receive treatment, and what the outcome will be for her, cannot yet be guaranteed.

Why is there still urgency now that FAYUVI is approved?

Sanfilippo is progressive, and damage that has occurred is irreversible. The FDA has approved FAYUVI. We now need to establish whether, and how soon, treatment is available and medically suitable for Muk. Her parents want to be ready to act and avoid losing precious time.

Why are we still fundraising, and how is my donation used?

Thanks to everyone who has given, the milestone of one million euros has been reached. The total cost of Muk’s treatment, medical preparation, travel and accommodation is not yet known. That is why we are continuing to raise funds. As more becomes clear, we will share it on this website and Instagram.

What happens to the money if treatment cannot go ahead?

If FAYUVI does not become available or proves medically unsuitable for Muk, donations remain under Stichting Muk’s management. The board may only spend the funds within the foundation’s purposes as set out in its statutes, for example on another medically suitable treatment, essential care or support for Muk, or activities relating to childhood dementia and Sanfilippo. We will explain any significant change in how the funds are used as specifically as possible on this website.

You can find more practical and financial answers on our full FAQ page.

Keep up with Muk’s next step

More photos and videos of Muk

See new moments and updates through @stichtingmuk on Instagram.

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