What causes transcobalamin deficiency?
Mutations in the TCN2 gene cause transcobalamin deficiency. The TCN2 gene provides instructions for making a protein called transcobalamin. This protein attaches (binds) to cobalamin and transports the vitamin to cells throughout the body.
What is the role of Transcobalamin II in vitamin B12 metabolism?
It primarily serves to protect cobalamin (Vitamin B12) from acid degradation in the stomach by producing a Haptocorrin-Vitamin B12 complex. Transcobalamin II (TCN2) binds cobalamin once it has been taken up by enterocytes of the terminal ileum and the “Intrinsic Factor-Vitamin B12” complex has been degraded.
Where is transcobalamin absorbed?
The absorption of dietary vitamin B 12 in the terminal ileum requires intrinsic factor, a glycoprotein secreted by the gastric parietal cells. It is transported in the blood by haptocorrin and transcobalamin II.
What is Transcobalamin II deficiency?
Transcobalamin II deficiency is a rare autosomal recessive disorder causing intracellular cobalamin depletion, which in turn causes megaloblastic bone marrow failure, accumulation of homocysteine and methylmalonic acid with clinical findings of failure to thrive, diarrhea, vomiting, pancytopenia, megaloblastic anemia.
Where is R protein produced?
salivary glands
Haptocorrin (HC), also commonly known as the R-protein, or the R-factor, or previously referred to as transcobalamin I, is a unique glycoprotein produced by the salivary glands of the oral cavity, in response to ingestion of food.
How does Mthfr affect B12?
Consume more folate and vitamin B12. Those with an MTHFR mutation are also at higher risk of being low in Vitamin B12 . Vitamin B12 can be supplemented easily without a prescription, whether as isolated B12 or present in multivitamins and B complex vitamins.
Is Transcobalamin a protein?
Transcobalamin (TC) is a 43-kDa nonglycosylated protein synthesized in most tissues and encoded by a gene located on chromosome 22. It binds to Cbl with a high affinity and delivers blood Cbl to cells by receptor-mediated endocytosis.
What can help absorb vitamin B12?
We already know from Harvard that B12 absorption can be increased by taking folate (another B vitamin, this one found in higher amounts in chickpeas, liver, pinto beans, lentils, spinach, asparagus, and avocado, among others).
Where is vitamin B12 stored in the body?
the liver
After the body uses these vitamins, leftover amounts leave the body through the urine. The body can store vitamin B12 for years in the liver.
How is transcobalamin deficiency diagnosed?
Diagnosis of TC deficiency is suspected based on megaloblastic anemia, elevation of total plasma homocysteine, and blood or urine methylmalonic acid. It is confirmed by studying the synthesis of TC in cultured fibroblasts, or by molecular analysis of the TCN2 gene.
Is transcobalamin 2 deficiency a common recessive disease?
Objective: Transcobalamin II deficiency is a rare autosomal recessive disease characterized by decreased cobalamin availability, which in turn causes accumulation of homocysteine and methylmalonic acid.
How much vitamin B12 is in transcobalamin?
Transcobalamin carries a minor part of the circulating vitamin B-12, and only ≈10% of the protein is saturated with vitamin B-12 (2). Transcobalamin transports vitamin B-12 into all cells of the body and is responsible for the transport of ≈4 nmol of vitamin B-12 every day (3). Open in a separate window FIGURE 1.
What is the function of transcobalamin 1?
Types Transcobalamin I (TCN1), also known as haptocorrin, R-factor, and R-protein, is a glycoprotein produced by the salivary glands of the mouth. It primarily serves to protect cobalamin (Vitamin B12) from acid degradation in the stomach by producing a Haptocorrin-Vitamin B12 complex.
What is transcobalamin deficiency?
Transcobalamin deficiency is a disorder that impairs the transport of cobalamin (also known as vitamin B12) within the body. Cobalamin is obtained from the diet; this vitamin is found in animal products such as meat, eggs, and shellfish.
What is transcobalamin II (TC II)?
Transcobalamin II (TC II) is the principal transport carrier protein system of cobalamin. The TC II gene is located on chromosome 22. In the absence of TC II, a serious and potentially fatal condition occurs. It presents clinically as follows: