To be a fit healthy individual, we have to feed our body regularly with food to provide energy and repair tissues. The foods that we eat are broken down into small packages and either used for growth and repair, stored to be available for periods of starvation, or disposed of as waste. Although, this explanation describes the basic process, it is of course much more complex. What started as a healthy steak or a glass of milk will have now been broken down into 20 individual “building blocks” known as amino acids. These amino acids travel in the blood stream and are supplied to the cells where they are needed. Generally speaking, we consume much more protein than the body needs. Therefore once we have finished with using what is needed, the excess is broken down by enzymes into smaller products, including ammonia and organic acids. The body is unable to tolerate large amounts of ammonia and organic acids; therefore a process in the liver converts these into harmless forms that can then be disposed of.
To understand your child’s condition it is helpful to look in more detail at how certain amino acids (such as Isoloeucine, Valine, Leucine) are broken down. Each amino acid has its own pathway using a series of enzymes. Each enzyme is essential to convert one substance to another. If an enzyme is faulty it results in the build-up of harmful products before the block, much in the same way that traffic builds up when there is a hold up on a busy road. If you have been told that your child has a methylmalonic aciduria or acidaemia an organic aciduria, this will mean that one of the enzymes is not functioning properly. The organic acids that build up before the block (methylmalonic acid) in the pathway give its name to the condition.