What is Transcobalamin II deficiency?
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.
What is the role of Transcobalamin 2?
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.
What is considered B12 deficiency?
A serum B12 above 300 pg/mL is interpreted as normal. Patients with B12 levels between 200 and 300 pg/mL are considered borderline, and further enzymatic testing may be helpful in diagnosis. Patients with B12 levels below 200 pg/mL are considered deficient.
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.
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 protein is needed for vitamin B12 absorption in the intestine?
Normally, vitamin B12 is readily absorbed in the last part of the small intestine (ileum), which leads to the large intestine. However, to be absorbed, the vitamin must combine with intrinsic factor, a protein produced in the stomach.
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.
Can Vitamin B12 deficiency be genetic?
Vitamin B12 is an essential micronutrient in humans needed for health maintenance. Deficiency of vitamin B12 has been linked to dietary, environmental and genetic factors. Evidence for the genetic basis of vitamin B12 status is poorly understood.
How do you know if your B12 is low in a blood test?
Complete blood count. This test checks the size and number of your red blood cells. If you’re low in vitamin B12, your red blood cells won’t look normal. They’ll be much bigger and shaped differently than healthy ones.
What Blocks B12 absorption?
Factors inhibiting B12 absorption The ODS reports that the taking of certain medications can lower the amount of B12 your body is able to absorb. These include: The antibiotic chloramphenicol (Chloromycetin) Acid reflux meds which are proton pump inhibitors (like Prilosec and Prevacid)
What causes Transcobalamin deficiency?
What causes elevated B12 in blood?
Conditions that can increase B12 level include: Liver disease (such as cirrhosis or hepatitis) Myeloproliferative disorders (for example, polycythemia vera and chronic myelogenous leukemia)
