Mitochondrial chain respiratory complex V deficiency

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MCRCVD is caused by a problem in several genes for example TMEM70 that provide instructions to create a protein known as transmembrane protein 70 which helps to stabilise a protein known as complex V. There are other genes that are involved in the development of MCRCVD, these genes may be involved in the production of the complex V protein which is used in the process of converting food into energy. If you have a problem with this gene then the complex V protein will be made incorrectly, or possibly not at all. Therefore, you will be unable to convert food into energy and this causes your body to become tired as your cells do not receive enough energy.  

The prevalence of this disorder is unknown, but it does form a part of a larger family of mitochondrial disorders. 

MCRCVD usually develops during the neonatal period in an individual’s life. The symptoms of this disease are: 

• Slow  
• Progressive myopathy  
• Neuropathy  
• Problem with balance and co-ordination (ataxia)  
• Retinitis pigmentosa  
• Sensory neuropathy  
• Muscle weakness 
• Cognitive impairment 

A doctor can diagnose MCRCVD using an individual’s medical history, symptoms, nature of disease and the doctor may also take bodily samples to take to do laboratory tests. There are a number of countries that are currently running diagnostic tests on this form of the mitochondrial disease, these countries are:  

• Belgium 
• Canada 
• Estonia  
• France 
• Germany  
• Italy  
• Netherlands 
• Portugal 
• Spain 
• Sweden  
• United Kingdom 

MCRCVD can be treated using an orphan drug known as alpha-tocotrienol quinone which is also known as vatiquinone, which is currently available in Europe and the USA. In the USA this orphan drug is being used to treat mitochondrial membrane transport disorders and the mitochondrial oxidative phosphorylation disorder and in Europe this orphan drug is being used to treat leigh syndrome. 

As an autosomal recessive inherited metabolic disorder which means that for a person to inherit this disorder, they will need to inherit it from their parents. Humans are made up of 46 chromosomes and we inherit 23 chromosomes from each parent, in the form of the egg and sperm which combine to determine the characteristics of the child. Every human being has two copies of the genes which are needed in order to produce the complex V protein. If both of these genes are faulty then MCRCVD will develop. The parents do not necessarily need to suffer from MCRCVD they can be carriers, carriers are people who carry one faulty gene for a particular protein, and they do not develop the disease because the other gene works correctly.  

In the event that both of the parents are carriers of MCRCVD. There is a: 

• 25% chance that one of the children will be unaffected by MCRCVD and will not be a carrier. 
• 25% chance that the child will inherit MCRCVD.  
• 50% chance that the child will be unaffected by MCRCVD and will be a carrier. 

References are available on request. Please contact us on 0800 652 3181 or by emailing contact@metabolicsupport.org.

Please note calls to 0800 numbers are free from UK landlines and mobiles. Calls from business lines may be charged – please check with your provider.

This information about metabolic diseases is provided by Metabolic Support UK and is intended for educational purposes only. It should not be used for diagnostic or treatment purposes.

Should you require more detailed information please contact Metabolic Support UK by email (contact@metabolicsupport.org) or by telephone ( 0800 652 3181). For specific medical information regarding a disorder or individual please contact your GP or Paediatrician. Metabolic Support UK accepts no responsibility for any errors or omissions nor does Metabolic Support UK assume any liability of any kind for the content of any information contained within this summary or any use that you may make of it.