Ausgewählte Beispiele aus der Physiologie des Kohlenhydratstoffwechsels und seiner Pathologie im Kindesalter: Glykogenspeicherkrankheit und Galaktosämie

In human pathology there are a number of diseases resulting only from the fact that the chemical structure of individual components of the body deviate from normal. Pauling calls such diseases „molecular diseases”. As changes in or failure of enzyme activities are the cause of the structural deviations, the collective name „Enzymopathies” has been suggested. As examples for „molecular diseases” two different forms of glycogenosis are mentioned. In the one type the ferment amylo‐1,6‐glucosidase is missing, which in glycogenolysis decomposes the 1,6‐glycosidic bond at the branching points of the molecule. Consequently the disturbed glycogen degradation causes the storage of pathological composed glycogen molecules in the body. In another type of this disease, the enzyme which causes branching of the glucose chains in the glycogen molecule (amylo‐1.4–1.6‐transglucosidase) is not sufficiently active or does not exist at all. In this way, a long chained glycogen results, which cannot be affected by the normal ferments of the glycogenolysis and obviously acts as a foreign body in the organism. In the group of enzymopathies there are also other kinds of diseases. They are caused if a ferment failure interrupts a metabolic pathway. Pathological symptoms can result as a consequence of this blockade if the substance following the missing ferment in the metabolic pathway does not exist or has a too low concentration. In this way, a number of symptoms can be explained in the third and most frequent form of glycogenosis, in which the glucose‐6‐phosphatase activity in the liver and kidneys is missing or is very low. In this way, a normally configurated glycogen is stored, from which, however, glucose cannot be freed in sufficient quantities. On the other hand, there could also be symptoms, if as a consequence of the missing ferment, the substrate of the ferment builds up in the organism and has a toxic effect. As example of this, galactosemia is mentioned. Before galactose can be utilized in the human body it must be converted to glucose. This takes place through the action of two ferments. If the ferment is missing (galactose‐1‐phosphate‐uridyl‐transferase) which leads the galactose to the metabolic pathway necessary for conversion, galactose is concentrated in the body. This causes irreversible damage to certain tissues.