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 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 transcobalamin absorbed?
ileum
Vitamin B12 binds to intrinsic factor (gastric glycoprotein from parietal cells) in GI tract, is absorbed from ileum, bound to transcobalamin II in plasma for transport to tissues.
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.
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.
Can you take vitamin B12 with polycythemia?
Don’t attempt vitamin B12 therapy without close supervision by your healthcare provider. High numbers of red blood cells (polycythemia vera): The treatment of vitamin B12 deficiency can unmask the symptoms of polycythemia vera.
Is Schilling test still used?
A Schilling test is also known as a Vitamin B12 absorption test. It was formerly used to determine whether a person was absorbing vitamin B12 normally. If not, then the test could pinpoint the cause of any vitamin B12 deficiency. Schilling tests are no longer used today.
What is methylmalonic acid used for?
The methylmalonic acid (MMA) test may be used to help diagnose an early or mild vitamin B12 deficiency. It may be ordered by itself but generally with a homocysteine test as a follow-up to a vitamin B12 test result that is in the lower end of the normal range.
Where does transcobalamin come from in the body?
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 happens if you have a transcobalamin 2 deficiency?
Transcobalamin II (TCII) deficiency is a very rare autosomal recessive disease. Megaloblastic anemia is the most specific sign of this disease. TCII is the primary transport for vitamin B12. The lack of vitamin B12 entry into the cells results in homocystinuria and methyl malonic aciduria.
Which is the transport protein system of cobalamin?
TC II is the principal transport carrier protein system of cobalamin. The TC II gene is located on chromosome 22 and is inherited as an autosomal recessive trait. In the absence of TC II, a serious and potentially fatal condition occurs. It presents clinically at 3–5 weeks of age with Failure to thrive, weakness. Vomiting and diarrhea.
Is there a prenatal test for transcobalamin II?
Diagnosis requires demonstration of the absence of protein capable of binding radiolabeled cobalamin and migrating with TC II on chromatography or gel electrophoresis, or by immunologic techniques. TC II is synthesized by amniocytes, permitting prenatal diagnosis. One thousand μg vitamin B 12 intramuscularly 1–2 times weekly.