What is mitochondrial disease?

What is mitochondrial disease?  
All cells in our bodies require energy to function properly. More than 90% of the body's essential energy is created by organelles within the cells called mitochondria (think of them as the power plants of the cell).  
 
Mitochondrial disease (sometimes referred to as Mito) is the collective term for a large group of genetic diseases where the mitochondria are unable to function properly. When mitochondria fail, too little energy is made within the body's cells. In one way or another, all these diseases result in not enough energy being made by the body to sustain effective organ function. 

Who does it affect?  
Mito is a rare genetic condition that is thought to affect about 1 in 5000 children born in Australia every year. Although Mito is more common in children, it can also affect adults. 

What are the symptoms?  
Mito is difficult to diagnose, as it can affect each individual differently and often mimics many other disorders.  

Any organ can be affected, as all cells (with the exception of red blood cells) contain mitochondria. Typically, the parts of the body that require the most energy to work correctly are most affected - such as the heart, brain, muscles, liver and eyes. Symptoms can include seizures, strokes, severe developmental delays, and inability to walk, talk, see, and digest food, combined with many other complications. Mito is often summarised as being able to cause any symptom, in any organ, at any age. 
 
How is it caused?  
At present, we know that more than 350 genes can cause Mito. In children, most types of Mito are caused when a fault in the same gene is inherited from both parents (which we call autosomal recessive inheritance); however, this is not always the case. They can also be inherited from only their mother) or aren't inherited at all - known as sporadic or de novo (new mutations) cases. 

What research into Mito is MCRI conducting?
We are currently only able to give a confident genetic diagnosis to around 60% of patients with Mito. Our research aims to ultimately diagnose all patients - this involves continuing to identify new disease-causing genes and to further streamlining the diagnostic processes used to prove that these genes are the cause of each condition.  

We are also using model systems within the laboratory to work out how different genes cause Mito and then use these systems to accurately trial drugs as potential treatments. 
  
What do we want to make possible for kids and families?  
At the MCRI, we are working to gain a better understanding of how Mito is caused and progresses and to find treatments or even a cure. We also want to make faster and more accurate genetic diagnosis possible for all families. Once kids have a diagnosis, this would allow them and their families access to future clinical trials and tailored support. 

Author: 
Dr Alison Compton leads the Gene Discovery group in MCRI's Brain & Mitochondrial group. Alison has established a substantial national and international profile in the field of mitochondrial disease ('Mito') gene discovery and incorporation of new technologies into genetic diagnosis.

Reference: 
Skladal D, Halliday J, Thorburn DR. Minimum birth prevalence of mitochondrial respiratory chain disorders in children.¯Brain. 2003;126(Pt 8):1905-1912. doi:10.1093/brain/awg170