Amino acids are vital substances without which our metabolism could not assemble proteins. In addition, they have other indispensable tasks, for example in the nervous system, in liver metabolism, in growth or in the formation of skin, hair and nails. Some amino acids can be produced by the human organism itself, while others must be supplied with food.
Enzymopathy
The processes involved in building up and breaking down amino acids and proteins in the organism are very complex; a whole series of enzymes and coenzymes are involved. If individual ones are defective or if they are not produced by the body at all or only in insufficient quantities – which is collectively referred to as enzymopathy – the result is, for example, a disorder in amino acid metabolism or diseases such as porphyria or Fabry disease.
Overview of the disorders
In most cases, the defects in amino acid metabolism manifest themselves in the fact that the precursors or intermediates cannot be converted into the final amino acid. The consequence is that these accumulate in the body, while the amino acid is missing or its quantity is insufficient to fulfill its function. This results in damage to tissues and organs from the intermediates and/or deficiency symptoms due to the amino acid deficiency.
In some cases, the transport of amino acids is disturbed, so that they can no longer be absorbed from the urine and transported back into the body, for example.
The amino acid metabolism disorders have one thing in common: they are based on a congenital genetic defect, i.e. they are inherited. However, most of them are very rare. The expression can vary – depending on whether an enzyme is completely absent or only limited in its function.
Diagnosis often difficult
Because a metabolic pathway involves several stations that require different enzymes, several disorders can occur in each case. The road to diagnosis is an odyssey for many of the disorders – because most of these diseases are very rare and the symptoms tend to be nonspecific, most doctors don’t know too much about them, and the diseases are difficult to recognize.
Exceptions are phenylketonuria and – in Bavaria – urea cycle defects, since screening tests are already performed for these in newborns and they are thus detected early. Often, the therapeutic spectrum is also quite limited – for rare clinical pictures, intensive research is hardly worthwhile for pharmaceutical companies.
