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Glitch in gene leads to clues in human disease

by CIFAR Nov 9 / 12

Cell with blue nucleus, green mitochondria, and red mitochondrial DNA. PHOTO COURTESY OF: Dr. Eric Shoubridge

A team of researchers led by Fellow Eric Shoubridge (McGill) in CIFAR’s Genetic Networks program discovered a new genetic defect that has been linked to a spectrum of rare and severe neurological disorders. The defect compromises the function of a critical component of cells, called the mitochondrion, which generates energy and ultimately keeps cells alive.

“Mutations that disturb mitochondrial energy production are increasingly recognized as causes of many diseases, especially neurodegenerative disorders,” explains Dr. Shoubridge. “Discoveries of novel genetic defects are so important because they help us to not only better understand the nature and functioning of the mitochondrial machinery, but also why its dysfunction sometimes causes diseases like Parkinson’s, epilepsy, or blindness.”

The researchers’ findings were recently published in The American Journal of Human Genetics.

The team studied the genes of a five-month-old infant who suffered from a deadly neurological disease. A glitch in a gene known in yeast but never characterized in humans called RMND1 was found to be the culprit in the infant’s disease. This gene helps mitochondria make their own proteins that are essential for producing energy for the cell; a failure to make these proteins results in the cell struggling to keep up with its normal agenda. This breakdown underlies a wide spectrum of neurological diseases.

Using a newly developed technique called whole-exome sequencing allowed the team to map all of the genes that code for proteins and also check for defects. As Dr. Shoubridge explains, “Whole-exome and, eventually, whole genome sequencing is going to change the face of genetic diagnosis making the process quicker and cheaper than we had ever thought possible a few years ago.”

Neurological disorders are tough to treat, but the team’s findings may inform future treatment opportunities. Understanding which genes are implicated in devastating disorders potentially could offer parents options for making reproductive decisions, such as genetically testing embryos or donor cells.