Biochemical Markers


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In Gaucher disease storage of glucosylceramide (glucocerebroside, the fatty tissue) takes place mainly in a certain cell type: the macrophage, explained Dr Ans Groener of the Dept of Biochemistry, Academic Medical Center, Amsterdam.


The macrophage changes in appearance due to the progressive increase of storage and becomes the so-called Gaucher cell. It also starts producing and excreting all kinds of proteins. In the plasma (blood) of patients, several factors are found in abnormal concentrations. One of these is chitotriosidase.

Chitotriosidase

Gaucher disease has been successfully treated since 1990. To closely follow the response of therapy, not only through clinical parameters, there was a strong need for biochemical markers.

This led in the early nineties to the discovery of chitotriosidase, an enzyme until then unknown in humans, by Prof Hans Aerts and his colleagues in our laboratory. Originally he wanted to call it gaucherase.

The enzyme is on average 600 times increased in the plasma of patients with Gaucher disease. The enzyme is excreted by Gaucher cells and its activity in the blood is a good measure for the total amount of Gaucher cells in the body.

Measuring this enzyme has proven its value in the follow up of the effect of treatment, in determining the enzyme dose during therapy as well as in establishing the severity of the disease and has helped decide the right moment to start therapy.

Unfortunately 5-6% of the population and therefore also 5-6% of patients with Gaucher disease are deficient for chitotriosidase. In these cases, chitotriosidase cannot be used as a marker.

CCL18 or PARC Test

Further research with advanced techniques has led to the finding of a new marker: the chemokine CCL18 or PARC. This protein is on average 29 times increased in the blood of symptomatic Gaucher patients. Just like chitotriosidase, the amount of CCL18 in the blood decreases during therapy. It is also produced by Gaucher cells and is therefore also a measure for the amount of Gaucher cells in the body.

We have discovered that especially in patients deficient for chitotriosidase, CCL18 can be used as an alternative biochemical marker to follow the course of the disease and the response on therapy, especially as it is found in all patients.

CCL18 was originally discovered as a result of research carried out by PhD student Mary Teresa Moran during her work at the University of Cambridge in Prof Tim Cox's laboratory. Her work was partly funded by the UK Gauchers Association


Gauchers News Contents

Source: Gauchers News March 2004.
© Copyright Gauchers Association 2004.