Mitochondrial complex I deficiency

What is Mitochondrial complex I deficiency?

It is a syndrome caused by the lack of a protein complex known as complex I. It is a mitochrondiral cell structure responsible for a process that enables many of the cells in the body to generate energy. Symptoms of the syndrome affect mainly the nervous system, skeletal muscles and the heart.

It occurs in around 1 in 8500 people. Mitochondrial complex I deficiency is the most common mitochondrial disease.

What gene changes cause Mitochondrial complex I deficiency?

Changes in many genes are responsible for causing the syndrome, including both nuclear and mitochondrial genes. It is inherited in an X-linked or autosomal recessive pattern depending on which gene mutation occurs.

Autosomal recessive inheritance means an affected individual receives one copy of a mutated gene from each of their parents, giving them two copies of a mutated gene. Parents, who carry only one copy of the gene mutation will not generally show any symptoms, but have a 25% chance of passing the copies of the gene mutations onto each of their children.

What are the main symptoms of Mitochondrial complex I deficiency?

The syndrome has many symptoms.

The main neurological symptoms include abnormal brain function,epilepsy, intellectual disability, involuntary movements and problems coordinating movements.

Features affecting physical activity include low muscle tone, muscle pain and extreme tiredness following physical activity. Higher than normal levels of lactic acid in the blood can also cause nausea, vomiting and rapid breathing. It also has the potential to be life threatening if left untreated.

Heart, liver and kidney issues are potential symptoms. As is vision impairment.
Some affected individuals have symptoms that as a group are caused by a specific syndrome. That is mitochondrial complex I deficiency triggers enough syndrome. Leigh syndrome is one such example of this.

How does someone get tested for Mitochondrial complex I deficiency?

The initial testing for Mitochondrial complex I deficiency can begin with facial analysis screening, through the FDNA Telehealth telegenetics platform, which can identify the key markers of the syndrome and outline the need for further testing. A consultation with a genetic counselor and then a geneticist will follow.

Based on this clinical consultation with a geneticist, the different options for genetic testing will be shared and consent will be sought for further testing.

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