Are normal enzyme levels enough to stabilize MLD?

A very interesting question came up today on the MLD Family Discussion List™ (a private list we run for MLD primary caregivers).  I thought it might inspire some thinking so I am sharing my answer here as well:

I have a question and I don’t know if anyone has an answer but I am wondering if anyone knows what truly stops this disease? Is it a normal enzyme level? Will the kids stop declining if the enzyme level stays normal? Are there other things that contribute to the stabilization of MLD?? 

Your first guess is actually correct – we really don’t know.  It will take lots of years of careful study looking at extended clinical trial/Phase III data, combined with more basic science bench work, natural history, and lots of patient & clinic reported progression/outcome data to really understand this disease.  And on top of a basic understanding we have hundreds of mutations to study.  We’re not planning on shutting down the MLD Foundation anytime soon!

From a practical perspective, the generally accepted consensus is that if the enzyme level in the blood is high enough (remember that “normal” levels vary all over the map and carriers with low blood enzyme levels appear to be metabolically “normal” people) then MLD’s progression will be dramatically slowed or halted. There is truth in this first order basic assumption – but it’s just the start of our understanding.
However (and not to scare you), there are three things to consider as we peel the MLD onion one layer (and there will be more subtleties as we further peel the MLD onion again in the future):
1) The first is that enzyme in the blood is of no value – it needs to be in the nerve cells that need it. Today’s therapies are primarily focused at crossing the CNS (central nervous system) into the brain. We measure enzyme levels in the blood and the CNS because it’s possible – brain biopsies on living people are not good! The state of our ability to get enzyme’s  large molecules reliably across the blood brain barrier (BBB) is in its infancy and the results are inconsistent at best.  The Milano gene therapy acknowledges this challenge by trying to make sure that whatever gets across the BBB produces 5-10x more enzyme than is typical hoping that the overproducing cells will share enzyme with their neighbors. Think of a gas tank in a car – a full tank shows “F” on the dial, but the engine won’t run if the fuel filter (BBB) is blocking the gas from getting to the engine (the brain).
2) The second thing to consider is once enzyme gets past the BBB will it get to all of the cells that need it?  Are some/many of those cells already compromised or unreceptive, does the enzyme (actually it’s a protein) get distributed to all regions of the brain, are the cells fixed so they keep on producing the enzyme or are they waiting for anther infusion like Enzyme Replacement Therapy (ERT) is designed to provide?  To continue the car analogy – the car may run if only 3 cylinders (brain regions) get fuel (enzyme) but you really need fuel to get to all of the cylinders (regions of the brain) to have the optimal/desired performance.
3) As mentioned, today’s therapies are primarily targeted at the brain/CNS, but our nervous system has a second component, the Peripheral Nervous System (PNS) that needs to be “fixed” as well.  The PNS makes sure the messages from the brain/CNS get to the muscles and systems elsewhere in the body.  We have historically seen a lot of transplants where the brain progression is slowed (stopped?) but the motor skills continue to decline (witness the many post-transplant children in wheelchairs).  The PNS is slightly different in its makeup than the CNS.  It also has a barrier, sometimes called the Blood Nerve Barrier (BNB), which is different from the BBB.  The common response when we ask why current research is focused on the CNS and not the PNS is that it makes sense to prioritize the CNS.  The challenge is that, to our knowledge, very little work has been done on the PNS barrier aspects of MLD. The car analogy is when the engine is running but the car is in neutral – lots of power under the hood but it is not getting to the wheels (limbs & organs) so the car is not going anywhere.
Also remember that some of these therapies require time to take hold.  The transplants need to engraft and the “good” cells take over/replace the bad cells before they can be effective. With ERT the thinking is they need to maintain somewhat consistent levels in the CNS which drives dosages and frequency of infusion.  Different issues, progressions and concerns will be at different priorities during the various early and long-term phases of each therapy.
And there are other therapies being developed as well … what if we reduced the amount of sulfatides produced so the little bit of enzyme that many MLD patients have doesn’t have to go as far?  This is called substrate reduction therapy (SRT) and hopefully will require a small molecule which, like alcohol, can more easily cross the BBB.  In the car analogy we still only get a little bit of gas through the clogged fuel filter – but what if the car was lighter and didn’t require as big an engine – their might be enough fuel getting by to be able to get from point A to point B?
We don’t have to completely understand all of this to make progress and see results in therapies.  As I mentioned above, the studies will go on for many more years and hopefully, today’s therapies will be good, tomorrows will be better, and in 5 or 10 years they will be even better as we better understand MLD, the body systems and the therapies of today and the future.  But for tomorrows therapies to be optimal, we do have to take the time to learn from every patient, every success, every valiant effort, every failure, and to explore every creative idea – many of which will lead us to increased knowledge even thought they are a practical dead-end.
At our upcoming Board meeting we are going to talk about investing in an independent formal MLD Registry to start to capture this scientific and medical history data in a more accessible scientifically managed database – we want the data to be there for future researchers to study when they have a creative idea.  And by investing, I don’t just mean a few dollars,  I mean that all of us, all of the MLD patients and their families, will be asked to contribute data as we begin to crowdsource MLD research in ways bigger than just one isolated project after another.

Newborn Screening – Should a Viable Therapy be a Requirement for a NBS?

The requirements for adding a Newborn Screen (NBS) to the RUSP (Recommended Uniform Screening Panel by the SACHDNC/DACHDNC (Secretary’s Discretionary Advisory Committee on Heritable Disorders in Newborns and Children) consists of four primary criteria:

  1. An acceptable treatment protocol in place that changes the outcome for patients diagnosed early with the disease
  2. An understanding of the condition’s natural history
  3. An understanding about who will be treated as a patient
  4. A NBS screening test that is reliable for both affected and unaffected patients and is acceptable to the public.

We are slowly becoming better at identifying and diagnosing Rare Diseases, unfortunately diagnosis occurs most often after symptoms are presenting. The great majority of the 7,000+ rare diseases do not have efficacious therapies. More than half of all rare diseases affect children and 30% of those children will not live to see their 5th birthday (1).

“There is always a therapy – it may not be a cure or a disease specific treatment, but we can always do something to optimize quality of life.” Paraphrase of Dr. Marc Patterson from the Mayo Clinic, Rochester MN.

With MLD and many other rare diseases, the diagnostic odyssey can last years and usually there are multiple misdiagnoses along the way.  If we don’t know what disease we are dealing with we can’t be sure we are providing the best care. A NBS for MLD, even without a treatment, would avoid the diagnostic odyssey and allow parents to know up front what to anticipate for the best care of their child – resulting in an optimized quality of life for their child and for the family.

There are good arguments for requiring a viable treatment before formalizing a NBS as well. Test and treat – don’t create a sense of helplessness and panic where there is no therapy. Don’t cause parents to take desperate actions to “do anything” for their child.

In the absence of a viable treatment a whole slew of questions come to mind … who is going to follow up with and provide social and medical care for the family, is there a financial impact on society for increased earlier care, would the role of the family support organizations change, what about the ethics of detecting a disease with a later onset, or parents that want to opt out except for disease with viable therapies, etc. …

Parents and families are starting to clamor for more medical knowledge sooner so they can better care for their children and industry is also awakening to the advantages of a pre-viable-therapy NBS – the potential negative this would have on the ability to capture natural histories that are necessary to get therapies approved being traded off for the identification of patients for potential study and real disease prevalence information.

I am calling for a NBS Therapy Summit or series of summits in the near future, perhaps starting next fall or winter, to encourage all interested and affected parties to share their concerns, views, issues, and thoughts.  An open discussion will give us all indications as to if the viable therapy requirement should be reconsidered.  If you are a public health official,  researcher, policy/regulatory person, SACHDNC committee member, parent, advocacy group member, an industry representative, clinician, or just interested in this topic I encourage your participation.

Follow this blog and I will keep you posted on any progress towards a summit..

Rare Disease Advocacy – Behind the Scenes

I ran across this article a few minutes ago. It’s a great insight into the challenges those of us working in rare disease advocacy working encounter.

Every person and agency mentioned in this article is someone we at the MLD Foundation regularly come into contact with as we work on behalf of those with MLD.

Intracerebral Gene Therapy Phase I/II Clinical Trial for MLD

We are pleased to share that a Phase I/II Intracerebral Gene Therapy clinical trial for MLD is now recruiting late infantile MLD patients. Dr. Patrick Aubourg and Dr. Caroline Sevin are the co-Principal Investigators.

We have posted complete details of the trial, including inclusion criteria, here.

This trial is based on many years of work in the lab, and on some parallel work with ALD that showed good results.

MLD Newborn Screening – We need your blood & urine!

The MLD Foundation is collaborating with researchers at the University of Washington who are working on developing a newborn screen for MLD that would hopefully address the problems encountered with traditional screening approaches caused by the MLD pseudo-deficiency.

For their work they need samples of blood and urine from 15 affected MLD individuals. All samples would be anonymous/de-identified to the researchers.

Criteria for participating is:

  • A confirmed diagnosis of MLD (No age restriction)
  • No treatment (no transplant)
  • Living within the US (due to need for quick return once samples are drawn)
  • Willingness to prick the skin to obtain blood
  • Willingness to follow instructions to obtain samples
  • Agree to mail samples within 24 hours of obtaining them
  • Agree to release the MLD Foundation and the University of Washington from any liability

If you would like to participate, please send an email to

We will respond with the release and send you the packet to obtain the samples.

We hope to have the sample collections completed in the next two weeks.

Thank you for considering to help develop a Newborn screen for MLD.

US Announces BRAIN initiative with $100m of 2014 funding

President Obama today announced the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) initiative and an anticipated $100M of US government funding in the next fiscal year. That is part of several hundred million more committed by private partners and foundations to this project to better understand how the brain works.

NIH Director Francis Collins discussing the BRAIN initiative

NIH Director Francis Collins – “It aims to bring together nanoscience, engineering, and neurology to make sense of how the brain works—how those circuits in the brain allow us to do all the complicated things that we currently don’t understand.”

There is a lot to understand and while we love the focus on the basic science of the brain – we anxiously await, and hope to contribute to, the goals of this project. And we can’t forget the European Commission’s €1bn award to their Human Brain Project.

What do you think? How would you like to see all of this support work together?

Not everyone is pleased:

RARE Patient Advocacy Summit – 2012

I was pleased to be the organizer and host for the RARE Project | Global Genes RARE Patient Advocacy Summit on September 29th, 2012. The day-long event with 140 in attendance and over 120 viewing via a live webcast.  Videos of the event are available below for viewing. Continue reading

List of Rare Diseases

This list was prepared using data supplied by the NIH’s Office of Rare Disease Research in late 2011. Please note that your medical providers and insurance payors probably have their own lists of diseases they think are rare – this list is for quick reference only. 

Quick Jump: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

Rare Diseases and Disorders Starting With “A”

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  • Aagenaes syndrome
  • Aarskog syndrome
  • Aase Smith syndrome
  • ABCD syndrome
  • Abderhalden Kaufmann Lignac syndrome
  • Abdominal aortic aneurysm
  • Abdominal chemodectomas with cutaneous angiolipomas
  • Abdominal cystic lymphangioma

Continue reading