Your body needs vitamin B-12, and this water-soluble nutrient is widely available in animal-based foods such as meat, chicken, fish, eggs and dairy products. For some people, however, consuming the recommended amount of dietary B-12 may not satisfy all their body's needs. This can be due to malabsorption syndromes that prevent their body from absorbing nutrients from foods. If you have one of these malabsorption syndromes, you may have genetically inherited it from your parents.
B-12 Functions
B-12 is crucial to the formation of red blood cells, and a deficiency will inhibit red blood cell production and result in anemia. B-12 also has influence over your neurological system. Lack of B-12 can result in tingling and numbness in your appendages due to nerve damage. If this is not treated in time, the nerve damage can be permanent. The treatment of hereditary B-12 deficiency involves lifelong supplementation with B-12.
Pernicious Anemia
Pernicious anemia occurs when your body lacks intrinsic factor, a substance that helps release B-12 from the protein-rich foods that bind it, thus allowing your gastrointestinal tract to easily absorb B-12. A congenital lack of intrinsic factor can result in impaired B-12 absorption. This results in decreased production of healthy red blood cells and the appearance of abnormally large, immature red blood cells called megaloblasts. Pernicious anemia that is inherited is present at birth, but other forms of pernicious anemia, caused by autoimmune disorders or a weakened stomach lining, can occur later in life, according to MedlinePlus.
Congenital Transcobalamin II Deficiency
Another form of genetic defect that can result in a B-12 deficiency is congenital transcobalamin II deficiency. Transcobalamin II is a B-12 transport-protein needed for the absorption, cellular uptake and recycling of B-12 in your body. Congenital transport protein deficiencies such as transcobalamin II deficiency are rare, a March 2003 article in "American Family Physician" notes. When congenital transcobalamin deficiency does occur, it results in immune and blood-related disturbances within the first months after birth, according to a 1983 article in the journal "Molecular and Cellular Biochemistry."
Imerslund-Grasbeck Syndrome
Imerslund-Grasbeck syndrome is another rare disorder that affects B-12 absorption. Its symptoms appear between the age of 4 months and several years old, according to Ralph Grasbeck of the Minerva Foundation Institute for Medical Research in Finland, who published a May 2006 article on the topic in "Orphanet Journal of Rare Diseases." It is caused by a defect in receptors for B-12 that are located in the cells that line your intestines. This condition typically causes failure to thrive, recurrent infections and fatigue.
References
- Linus Pauling Institute at Oregon State University; Vitamin B-12; Jane Higdon, Ph.D., et al.; August 2007
- University of Maryland Medical Center: Vitamin B12
- MedlinePlus: Pernicious Anemia
- "American Family Physician"; Vitamin B12 Deficiency; Robert C. Oh, et al.; March 2003
- "Molecular and Cellular Biochemistry"; Genetic Patterns of Transcobalamin II and the Relationships With Congenital Defects; M. Frater-Schroder; 1983
- "Orphanet Journal of Rare Diseases"; Imerslund-Grasbeck Syndrome (Selective Vitamin B12 Malabsorption With Proteinuria); Ralph Grasbeck; May 2006
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