Pompe (Inherited Metabolic Disorders)

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Pompe disease is an inherited, genetic disorder which results in the lack of an enzyme 'acid alpha-glucosidase’. Pompe disease is also known as acid maltase deficiency or glycogen storage disease type II. To understand the implications of this it is useful to know a little about this enzymes normal activity. The human body contains many different types of cells. A basic cell has many components as you can see from the diagram below, including the nucleus which contains chromosomes. Within the cell there is a small compartment called the lysosome - this contains all the enzymes the cell needs to manage its recycling of waste products.

Urgent advice: Covid-19 - Pompe

Patients with Pompe disease are at a really high risk with COVID-19 in view of their neuromuscular breathing difficulties -  many are already using artificial ventilation. 

The video below is an inspirational look at how people around the world are coping and trying to stay well. 

https://www.youtube.com/channel/UCTIgBCHotaPy0LrMVAD1QWQ

For more information visit www.worldpompe.org/

Inheritance

Pompe disease is an inherited genetic disorder described medically as an 'autosomal recessive disease’.  Each person has 23 pairs of chromosomes which contain genes – they receive 1 set from each parent. Genes contain the necessary information to allow our body to be formed and to function. It is estimated that every human being has 8 -10 genes that have changes within them (called mutations) however only some can cause disease. Pompe disease only produces symptoms when both copies of the gene are affected. This may well have occurred when both parents have 1 copy of the genetic mutation. They are said to be carriers (ie without any evidence of disease) but their offspring may inherit both copies of the faulty gene.

There are other possibilities – eg if 1 parent has Pompe disease and the other either has no mutation or is a carrier. In the former case all the children will be carriers and the latter there is a 50% chance of having an affected child and a 50% chance of a carrier.

If you would like further information about the inheritance pattern in your personal circumstances or to know whether it is likely that any other members of your family are affected please discuss this with your physician or specialist nurse.

Symptoms

The signs and symptoms of Pompe disease are directly related to the muscles affected. The disease is progressive in nature, and affects proximal, respiratory and cardiac (infants) muscle.

There are currently thought to be 2 main types of Pompe disease:

Infantile

  • Classic infantile Pompe is the most severe end of the spectrum with rapidly progressive cardiomegaly (enlarged heart) hepatomegaly (enlarged liver) weakness and hypotonia ('floppy’). This leads to early death usually in the first year of life
  • Infantile variant Pompe has a slower progression and less severe cardiomegaly. It usually presents during the first year of life

Late onset

  • Juvenile pompe presents later than infancy and typically does not include severe cardiomyopathy
  • Adult onset is characterised by a slowly progressive myopathy (muscle weakness) that presents as an adult.

Treatment

Enzyme replacement therapy (ERT)

Pompe disease is currently treated with Enzyme replacement therapy which directly replaces the missing /malfunctioning enzyme.  This is an intravenous infusion that is given once per fortnight initially in. The infusion is then administered at home over usually between 4-5 hours.  It is possible to learn how to administer and manage this medication independently. Some patients may have mild infusion reactions and appears to be more likely if the infusion is administered at a time of intercurrent illness.

Supportive treatment

This will vary considerably depending upon the nature and severity of the symptoms experienced. Pompe is a progressive disorder and therefore requires regular assessment to identify which treatments are appropriate. In general these tests should include assessment of cardiac and respiratory function (heart and lung), muscle strength and function, safety when swallowing and diet/weight maintenance.

It is likely that people affected by pompe will also need to visit other doctors eg a neurologist, respiratory and/or cardiac physician as well as other healthcare professionals such as the physiotherapist, occupational therapist, speech therapist and dietician. At Addenbrooke’s, Pompe patients are cared for by an experienced metabolic physician and a specialist nurse who will co-ordinate assessment, treatment and supportive care as necessary, with access to the multi disciplinary team. The input and support of a local physician is also essential.

It is considered important for patients to adopt a healthy lifestyle by following dietary advice, exercising within limits and to avoid smoking in order to maintain or improve general health.

Advances in medicine mean that there are new treatments under investigation  in clinical trials for Pompe disease  Further information can be found on the clinical trials.gov website  and  on our research page for any trials currently available at Addenbrooke’s.