- A curious adult from the US
July 13, 2018
Perhaps you have heard of the “blood type gene”. The blood type gene can come in three different versions: A, B or O. The versions you inherit determine whether your blood is type A, type B, type AB, or type O.
Appropriately, the blood type gene is named ABO. When we talk about the genetics of blood type, we typically only refer to the ABO gene. And that’s okay. Usually we don’t need to go into greater detail.
A matter of inheritance
It’s worth noting that the Bombay blood group is quite rare. It was only first discovered in Bombay (now Mumbai) in 1952. It affects one person out of 10,000 in India. It is a bit more common in Taiwan, where it affects one person in 8,000.
It’s even rarer in other parts of the world! Among people of European ancestry, Bombay blood group is literally a one in a million event.
But as rare as it might be, it does happen. And when it happens, it can result in unexpected patterns of inheritance.
The versions of FUT1 are called “H” and “h” for a reason. When the “H” version of FUT1 attaches a sugar to the chain, the chain is called the “H antigen”. When the broken “h” version of FUT1 fails to attach a sugar to the chain, the H antigen is not formed.
The “H” version of FUT1 is dominant to the “h” version. If you get one working “H” version of FUT1, it is enough to do all the work. The blood cells all get the H antigen.