Researchers from the McGill University Health Centre in Canada expect that the discovery will help doctors better diagnose this rare genetic disorder and open the door to new treatments.
"We found that a second transport protein was involved in the uptake of the vitamin into the cells, thus providing evidence of another cause of hereditary vitamin B12 deficiency" Dr David Rosenblatt, one of the study's co-authors, said.
"It is also the first description of a new genetic disease associated with how vitamin B12 is handled by the body," Rosenblatt said in a statement.
Researchers worked with two patients showing symptoms of the cblF gene defect of vitamin B12 metabolism but without an actual defect in this gene.
It led to the discovery of a new gene, ABCD4, associated with the transport of B12 and responsible for a new disease called cblJ combined homocystinuria and methylmalonic aciduria (cblJ-Hcy-MMA).
Using next generation sequencing of the patients' genetic information, the scientists identified two mutations in the same ABCD4 gene, in both patients.
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"We were also able to compensate for the genetic mutation by adding an intact ABCD4 protein to the patients' cells, thus allowing the vitamin to be properly integrated into the cells," Dr Matthias Baumgartner, senior author of the study said.
Vitamin B12, or cobalamin, is essential for healthy functioning of the human nervous system and red blood cell synthesis.
Unable to produce the vitamin itself, the human body has to obtain it from animal-based foods such as milk products, eggs, red meat, chicken, fish, and shellfish