The Ii blood group system is a way of classifying blood based on the presence of specific antigens, or molecules that are expressed on the surface of red blood cells. Specifically, this blood group contains an “I” antigen and an “i” antigen. The i antigen is normally only expressed on the surface of red blood cells in the fetus and in newborns. As infants develop, the I antigen forms and becomes expressed on the red blood cells instead of the i antigen.
Most individuals will have the standard adult ratio of I antigen to i antigen by age 20 months. However, in some individuals, a genetic mutation causes their red blood cells to contain mainly i antigen, even as adults. These occurances are due to changes in a gene called GCNT2. We inherit our genes in pairs, one from each parent typically. Our genes are what control the growth, development and function of our bodies. If a mistake or error occurs in a gene, it can cause problems.
When individuals produce antibodies, or proteins that recognize foreign substances, to the I antigen, they may develop hemolytic anemia, a condition where the red blood cells are destroyed and removed from the bloodstream when they shouldn’t be. Additionally, when individuals produce antibodies to the i antigen, they may develop leukemia and other blood diseases.
High amounts of i antigen have also been associated with congenital cataracts (problems with the lens of the eye at birth), oncogenesis (the formation of cancer), thalassemias (a type of blood disorders), and sickle cell anemia (a condition involving problems with red blood cells) in some individuals. If you or a family member has been diagnosed with this conditiony, talk with your doctor about the most current treatment options.
Description Last Updated: Feb 06, 2018