A new disorder in metabolism of vitamin B₁₂

This week, researchers at McGill’s Department of Human Genetics and Genome Quebec—in collaboration with others from the United States, Switzerland, and Germany—published the discovery of a new genetic defect that causes an inability to break down vitamin B₁₂.

Vitamin B₁₂ plays an essential role in the proper functioning of our nervous system and intestinal tract. Most of us are able to get sufficient vitamin B₁₂ from our food, although vegans may require dietary supplements.

This breakthrough, published in the scientific journal Nature Genetics on August 26th, describes the newly discovered disorder called cblJ. This first came to light when two unrelated infants showed symptoms characteristic of vitamin B₁₂ deficiency soon after birth.

Suspecting a genetic inability to metabolize the vitamin was to blame, the researchers tested the two infants to see if their genetic defect matched with any that are already known. Finding no similarity, the researchers studied the genes of these infants and identified a new mutation in a gene called ABCD4, which results in the vitamin being retained in lysosomes (stomach-like pockets in cells) rather than releasing it into the cytoplasm, a cellular milieu.

The identification of this novel gene, essential for vitamin B₁₂ metabolism, increases our understanding of vitamin function, and helps classify patients with the genetic defects in B₁₂ metabolism so that appropriate treatments can be given.

Food security, malnutrition and obesity

While some nations, including the United States, suffer from an epidemic of obesity, there are many countries in the world stricken with abundant malnutrition. In some countries, the two disorders even co-exist.

Laurette Dubé, a McGill professor from Desautels Faculty of Management, and Patrick Webb of Tufts University have proposed that this co-existence occurs due to food and nutrition insecurity.  This issue occurs where people lack both physical and economic access to the safe, nutritious food which helps them live an active and healthy life.

The work, published in July 2012 in the Proceedings of the National Academy of Science (PNAS), argues that ensuring food security is a highly complex task—one that involves a country’s food source from agriculture, the health and disease status of its people, and finally, the environment.

These factors may partially explain the differences between conditions for malnutrition and obesity, and at the same time help policy makers determine strategies to ensure food security for everyone.

Coffee and Parkinson’s disease

Carriers of Parkinson’s suffer from tremors, shaking, slowed movement, loss of balance and excessive daytime sleeping. Coffee intake has repeatedly been shown to reduce the risk of developing Parkinson’s disease.

Students and others regularly abuse coffee to stay awake. This property led researchers to believe it had potential to treat excessive daytime sleeping.

Researchers at McGill University’s department of neurology, led by Dr. Ronald B. Posthuma, in collaboration with researchers from Toronto and Brazil, studied the effects of coffee on 61 patients with Parkinson’s. Their work was published in August 2012 in the Journal of Neurology.

Surprisingly, researchers found that caffeine had no effect on the sleepiness that these patients suffered from; it only reduced the level of tremors observed by the patients.

The study’s findings add to anecdotal and scientific evidence that caffeine can help relieve symptoms of Parkinson’s disease. Further work is required to fully understand how coffee can help alleviate these symptoms.