Just over a decade ago, Pierre Lavoie was cycling hundreds of kilometres to raise awareness for lactic acidosis. The inherited recessive disorder, which is especially present in the Saguenay-Lac-Saint-Jean region, robbed him of two of his children. Thanks to genomics, it is now possible to detect and prevent this disease.
Finding the culprit behind lactic acidosis
In 1999, Pierre Lavoie undertook a worthy challenge: to pedal 600 km, day and night, in order to raise awareness and research funds for lactic acidosis, a disease that had taken two of his four children. For Pierre, it was time to act. A research team headed by Dr. John D. Rioux shared his enthusiasm. Their goal was to find the gene responsible for lactic acidosis.
After five years of research, scientists found the defective gene, known as the LRPPRC. A change in the sequence of the letters (a T instead of a C) on chromosome 2 was thought to be responsible for the disorder. This discovery paved the way for better prevention.
ABOUT LACTIC ACIDOSIS
Lactic acidosis involves a deficit of cytochrome oxidase, an enzyme essential to the proper functioning of the body. Its role is to deliver energy to the cells. When the enzyme is present in a lower quantity or lacking altogether from organs such as the liver, kidneys, muscles and brain, the body is unable to meet its energy requirements, especially when these increase (e.g. when fighting an infection). The lower level of energy is accompanied by a buildup of lactic acid in the blood. This imbalance can be life threatening.
As early as 1998, a research group headed by Dr. John D. Rioux at the Massachusetts Institute of Technology in Boston was studying lactic acidosis with researchers and doctors from Chicoutimi, Toronto and the McGill University and Génome Québec Innovation Centre.
Since discovering the lactic acidosis gene in 2003, Dr. Rioux’s research group, located at the Montreal Heart Institute, has continued to study the disease alongside Dr. Christine Des Rosiers, her team and researchers from Université de Montréal, Université du Québec à Chicoutimi and collaborators in the United States and Europe. Their goal is to better understand how the physiological and molecular mechanisms involved in the defective LRPPRC gene cause lactic acidosis and to find ways to treat the disease.
Prevention through screening
According to Pierre Lavoie, preventing lactic acidosis meant developing screening tests. Dr. Daniel Gaudet of the Université de Montréal Community Genomic Medicine Centre at Chicoutimi Hospital was up to that challenge. In addition, these screenings needed to be inexpensive. Génome Québec was there to help.
Relying on technology used to sequence the human genome, it is now possible, with a single test that costs only $20, to screen for five different diseases (lactic acidosis, ataxia of Charlevoix-Saguenay, cystic fibrosis, motor and sensory neuropathy and tyrosinemia).
UNDERSTANDING HOW RECESSIVE DISORDERS ARE INHERITED
Some inherited diseases – diseases caused by a defective gene passed on from one generation to the next – are recessive. To inherit a recessive disorder, a person must have two copies of the defective gene. People who have only one copy are carriers of the disease. This means they do not have the disease but can transmit the defective gene to their offspring.
Given that the defective gene has now been identified, there is reason to hope that a drug to treat the disorder will see the light of day in the years to come