hh blood group facts for kids

The hh blood group, also known as the Bombay blood group, is a very rare blood type. It's special because people with this blood type don't have a certain substance (called an antigen) on their red blood cells that most other people have.

This unique blood type was first found in 1952 in a city called Bombay, which is now known as Mumbai, in India. It was discovered by a doctor named Y. M. Bhende. While it was found in India, it's also seen in other parts of the world, especially in the Middle East, like Iran.

What Makes the hh Blood Group Special?

Most people have A, B, or O blood types. These types depend on whether you have A antigens, B antigens, or neither, on your red blood cells. But there's also another important antigen called the H antigen. Almost everyone has the H antigen.

People with the hh blood group, however, do not have the H antigen. This means their red blood cells are missing a key building block that's needed to make the A and B antigens. So, even if they have the genes for A or B blood types, they won't show up on their cells.

Why is it So Rare?

The hh blood group is rare because it requires a specific combination of genes. Both parents must carry the special gene for their child to inherit this blood type. This makes it much less common than the regular A, B, AB, or O blood types.

How Does it Affect Blood Transfusions?

For people with the hh blood group, receiving a blood transfusion can be tricky. They can only receive blood from another person who also has the hh blood group. If they receive blood from someone with a regular A, B, AB, or O blood type, their body would see the H antigen as a foreign substance. This could cause a serious reaction.

Because it's so rare, finding matching blood for someone with the hh blood group can be very difficult. Blood banks often keep special records of donors with this blood type to help in emergencies.

Discovery and Importance

The discovery of the Bombay blood group helped scientists understand more about how blood types work. It showed that the H antigen is a foundation for other blood antigens. This knowledge is very important for safe blood transfusions and for understanding human genetics.