Genes Identified that Control Vitamin B12 Metabolism

Researchers have identified genes that underlie two severe diseases of vitamin B12 metabolism, the cblA and cblB forms of methylmalonic aciduria, which may cause brain damage, mental retardation and even death if not detected in infancy or early childhood. Their findings were published in the November 26, 2002, issue of the Proceedings of the National Academy of Sciences.

Investigators from the University of Calgary (Canada) identified the vitamin B12 genes in bacteria, and then found their counterparts in humans by utilizing data available through the human genome project. Confirmation of the role of these genes in vitamin B12 metabolism was obtained through collaboration with the diagnostic facility and cell bank for genetic).

"We have identified two different genes that are critical to the processing of vitamin B12 by finding mutations in patients who have particular forms of methylmalonic aciduria,” explained first author Melissa Dobson of the University of Calgary. "Methylmalonic acid is a chemical intermediate in the breakdown of proteins and other substances. It accumulates in the body and is excreted in large amounts in the urine because the blocks in the processing of vitamin B12 prevent its metabolism.”





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