What is Hexosaminidase A (HEX A)
All forms of Tay-Sachs (Infantile, Juvenile and LOTS) are due to a lack of, or reduced level of the Hexosaminidase A (HEX A) enzyme. Therefore, it is important to understand exactly the role of this enzyme in the body and why it is so important. It is also important to understand what an enzyme actually is. We have done our best in the below to translate the scientific language to something most of us can understand!
What is an enzyme?
The scientific explanation of an enzyme is:
“Enzymes are proteins that catalyze (i.e., increase the rates of) chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates sufficient for life.”
Confusing isn’t it! In it’s most basic sense, an enzyme speeds up chemical reactions within the body so that a molecule in the body can be turned into something which can be used by the body. All cells require enzymes to survive and function which us why they are vital for us to live.
What does Hexosaminidase A (HEX A) do?
The scientific explanation of HEX A is:
“The HEXA gene provides instructions for making one part (subunit) of an enzyme called beta-hexosaminidase A. Specifically, the protein produced from the HEXA gene forms the alpha subunit of this enzyme. One alpha subunit joins with one beta subunit (produced from the HEXB gene) to form a functioning enzyme.
Beta-hexosaminidase A plays a critical role in the brain and spinal cord (central nervous system). This enzyme is found in lysosomes, which are structures in cells that break down toxic substances and act as recycling centers. Within lysosomes, beta-hexosaminidase A forms part of a complex that breaks down a fatty substance called GM2 ganglioside.”
The above is outlining the role of HEX A and what it breaks down – which is GM2 ganglioside. Its role within the body is vital as it does not allow the build up of the GM2 ganglioside within the brain.
What is the link between Hexosaminidase A and Tay-Sachs?
The scientific link between the two is:
“Tay-Sachs disease occurs when hexosaminidase A loses its ability to function. People with Tay-Sachs disease are unable to remove the GalNAc residue from the GM2 ganglioside, and as a result, they end up storing 100 to 1000 times more GM2 gangliosides in the brain than the normal person.”
From the above it is possible to understand how vital HEX A is within the body. Tay-Sachs is due to the lack of, or reduced level of HEX A within the body and this results in GM2 ganglioside building up in the brain. As a waste product having this build up of GM2 ganglioside results in severe problems in the individual.
The most important thing to take away from the above is that Hexosaminidase A (HEX A) is a vital enzyme produced by the body to break down GM2 ganglioside. Individuals with Tay-Sachs have a problem producing this enzyme and the result is a build up of a waste product called GM2 ganglioside