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Pompe disease, a rare but important genetic condition

As I plan to become a clinical geneticist, I should write more often about genetic conditions. But I don’t want to duplicate the articles of Wikipedia, my aim is to provide useful sources of information. Pompe disease is a rare disorder caused by the deficiency of the acid alpha-glucosidase enzyme. It’s inherited in an autosomal recessive manner. The patients can’t break down glycogen. According to the Wiki article:

It is the only glycogen storage disease with a defect in lysosomal metabolism, and was the first glycogen storage disease to be identified—in 1932. The build-up of glycogen causes progressive muscle weakness (myopathy) throughout the body and affects various body tissues, particularly in the heart, skeletal muscles, liver and nervous system.

I’d like to show you the main characteristics of the disease and of the diagnosis.

us_pompebaby.jpg
Head lag caused by muscle weakness

final_pomp_xray.jpg
Cardiomegaly in Infant

webimages_01.jpg

heart31.jpg
The heart of a 9 month old child who died of congestive failure. (Original material by Horton Johnson)

Why do we have to talk about Pompe? The reason is diagnostic delay. The diagnosis often poses a dilemma due to the rarity of the disease, the variable rates of progression and the unspecific phenotypic features. What kind of disorders do we have to list as a part of the differential diagnosis?

  • Spinal muscular atrophy
  • Hypothyroidism
  • Endocardial fibroelastosis
  • Myocarditis
  • Congenital muscular dystrophy
  • Glycogen storage diseases
  • Mitochondrial, peroxisomal diseases
  • Danon disease
  • Myasthenia gravis, Becker’s muscular dystrophy

Just take a look at the diagnostic delay diagram, there are from 2 to 4 years between the first symptoms and the diagnosis:

diagdelay.gif

How can we confirm diagnosis? An acid-glucosidase (GAA) assay can be performed on skin fibroblasts or muscle biopsy. A non-invasive and relatively reliable test is GAA assay in blood collected on filter paper. But laboratory testing and molecular analysis must be also taken into consideration.

Some words about the treatment. Of course, genetic counseling can help parents as it provides them information about a possible future pregnancy. According to the wiki article:

On April 28, 2006 the US Food and Drug Administration approved a biologics license application (BLA) for Myozyme (alglucosidase alfa, rhGAA), the first treatment for patients with Pompe disease primarily developed by Dr. Yuan-Tsong Chen while he was at Duke University. Myozyme falls under the FDA Orphan Drug designation and was approved under a priority review.

Although Pompe disease is a rare condition (estimated to occur in about 1 in 40,000-300,000 births), it should get much more attention as the diagnostic delay still means a crucial problem in treating these children.

References:

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32 Comments Post a comment
  1. What happened to your Sonic Hedgehog post?

    February 7, 2007
  2. What do you mean? Is there any problem with that? I’ve just made an update but everything looks the same for me.

    February 7, 2007
  3. Oh, it became private, I have no idea why. Now, it’s published again. Thank you, Darmok!

    February 7, 2007
  4. Oh, you’re welcome. I had wanted to read it again and couldn’t figure out what had happened to it!

    Wow, that is one big heart.

    February 7, 2007
  5. Yes, only from a ninth month old child, incredible.

    February 7, 2007
  6. Hey, I’m a Pompe patient and a friend of mine pointed out your blog to me. I’m glad you’re taking interest in the disease. I have a personal blog about Pompe. Visit it at http://www.fightpompe.com

    February 18, 2007
  7. I was at an MDA clinic directors conference in Nov, 2005 when someone from Abbott Labs presented information about the treatment. It was absolutely astounding to see what treatment can do, though for reasons not fully understood, it’s not a miracle cure for everyone with Pompe’s.
    Another interesting thing is that Abbott is making the drug available for all patients with Pompe’s for free — yes, I said free. With the rarity of the disease, this is not a commercially viable treatment, so they’re developing it as a humanitarian gesture.

    February 21, 2007
  8. By chance, don’t you have a link to him? I’m now blogerviewing a Pompe patient and I’d like to tell him about it.

    February 21, 2007
  9. Janet #

    My Hushand, Was a big & strong man & now his muscles are weak & his hand is weak, Could this be pompe disease?

    March 20, 2007
  10. Martin #

    Please note that myozyme(R) was EMEA-approved for infantile as well as juvenile/adult M. Pompe but proof for effectiveness in juvenile/adult diesease is still missing (a least, there’s a study going on). M.

    May 30, 2007
  11. Sam #

    Does anyone know if this disease can be diagnosed during pregnancy?

    July 3, 2007
  12. It’s not easy to diagnose during pregnancy. A proper family screening can be very useful.

    July 3, 2007
  13. Your blog and your every post always fascinate me. Unlike most of my health practitioner friends, you’re the only person I know who is engrossed with Science and the human body/health yet has this time to write and write and write. Keep going pal.

    November 5, 2007
  14. You always have some kind words for me. :)

    To be honest, that’s the post I’m most proud of.

    November 5, 2007
  15. Michelle #

    What kind of genetic testing is available for Pompe Disease? And approximately how much does it cost?

    February 28, 2008
  16. ROCK #

    There is a dried blood spot test for Pompe disease. It costs around $250 dollars but is covered under most insurances. Genetest.org will explain Pompe genetic tests. It is also known as acid maltase deficiency.

    March 13, 2008
  17. drena #

    how serious is pompe disease? can it be diognoised later in life or do you have it from birth? is it being treated in the u.s.a? what kind of treatment is there?

    May 20, 2008
  18. Drena,
    There are Infantile, juvenile and adult onset forms.

    And here is a link about the treatment options: http://en.wikipedia.org/wiki/Glycogen_storage_disease_type_II#Treatment

    May 24, 2008
  19. Ma. Charisse B. Macaraeg #

    where can we find a patient having pompe disease here in the philippines?

    November 3, 2008
  20. You can try this. Juan is blogging at http://www.fightpompe.com/

    November 3, 2008
  21. Aireen B. Lee #

    I read your article, and i decided to write. About the no. 28 question, yes, you can find it here in the Philippines. Unfortunately my niece, experienced the hypertonic cardiomyopathy, and part of the lobe of her lungs collapsed. The doctor suspected it maybe a pompe disease. She undegone the blood test. Such blood test will be sent to Taiwan for testing. Right now, we are praying that it will be negative.

    November 11, 2009
  22. i like the proposal writing part i have to keep these points in my mind for writing a better proposal in future as i am also a small business entrepreneur..thanks for sharing..

    October 6, 2011
  23. fapdu #

    My brother recommended I might like this web site. He was totally right.
    This post truly made my day. You cann’t imagine just how much time I had spent for this info! Thanks!

    November 11, 2012

Trackbacks & Pingbacks

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  9.   Face to face: Gaucher Disease by medtrials.info

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