Inborn errors of metabolism (IEM) are a very rare group of inherited diseases that cause problems with your metabolism.
Your metabolism is a series of chemical reactions that occur in your body’s cells. These reactions allow your body to break down nutrients and create energy. If you have an IEM, then your metabolism won’t be working properly; this can lead to very serious problems with your brain development, and cause problems for your heart and lungs.
These diseases mostly start when people are born, or in very early childhood. In the UK, the NHS newborn bloodspot screening programme is designed to pick up on these types of diseases. This involves taking a blood sample to find out if your baby has one of nine rare but serious health conditions.
There are lots of different types of inborn errors of metabolism. Sometimes you might see them divided into different types:
The charity Genetic Disorders UK has information about these conditions and also offers support to patients and their families.
If you have an IEM, the type of treatment recommended will vary depending on what the condition is, how severe it is and the risks and benefits of the treatment. Having a stem cell or bone marrow transplant is one way to help, particularly in cases of young children when a well-matched donor is available.
The doctors’ choice of transplant may be slightly different, depending on the exact type of condition you have, your age and how well you are. If you have a brother or sister, your doctors will normally test them first to see if they’re a match and whether you can have a transplant using their stem cells.
If not, then they may consider an allograft transplant – when your new stem cells are donated by an unrelated donor – or a haplo-identical transplant using stem cells from one of your relatives whose tissue type partially matches yours. Find out more about transplants here.
If you’re a parent supporting a child through a transplant, read our page for parents.