This article from 2023 explores how genetic variations in the gene for the transcobalamin receptor (CD320) affect vitamin B12 uptake into the brain in elderly individuals. Vitamin B12 is vital for producing red blood cells, maintaining the nervous system, and other critical processes. The study found that certain gene variants are linked to higher levels of a specific form of B12 in the blood (holotranscobalamin or holo-TC), which might suggest altered cellular uptake.
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Key findings include:

Gene Variants Detected: Four specific changes in the CD320 gene were found. About 12% of elderly individuals carry at least one of these variations.

Impact on B12 Measurement: People with these variants had higher holo-TC levels. Holo-TC is a marker used to measure B12 availability in the body, but this study suggests it might not always reflect true B12 status.

Clinical Implications: Since B12 status is often assessed using multiple markers like holo-TC, total B12, and methylmalonic acid, these findings suggest that genetic variations could lead to misleading test results in some individuals.


This study highlights the need to adjust current diagnostic tools for B12 deficiency to account for genetic variations in the CD320 gene. Without these adjustments, some individuals might be misdiagnosed as having normal B12 levels despite potential deficiency.


Link: https://www.clinicalnutritionespen.com/article/S2405-4577(23)00116-X/fulltext