Intrinsic factor is a protein made by the stomach that helps the body take in vitamin B12. Some people are born without the ability to make this protein. When this occurs, it is called a congenital lack of intrinsic factor. Congenital means that a condition is present at birth.

What is going on in the body?

In most people, the stomach makes the intrinsic factor protein. This protein attaches to the vitamin B12 that is taken in with the diet. The protein allows the vitamin B12 to be taken up through the intestines and into the bloodstream. Once the vitamin is in the bloodstream, the body is able to use it.

When children are born without the intrinsic factor protein, they develop vitamin B12 deficiency. This deficiency can cause low red blood cell counts, called anemia. The anemia that occurs in this condition is called pernicious anemia.

What are the causes and risks of the disease?

A congenital lack of intrinsic factor is thought to be inherited in most cases.