Allelic frequency of CHIT1 variants in the Portuguese population

Abstract

Chitotriosidase (EC.3.2.1.14) is an enzyme secreted by activated macrophages. This chitinase is useful as a biochemical marker in several lysosomal and nonlysosomal diseases due to its increased activity in such conditions (MIM#600031). In Gaucher Disease type 1 (GD, MIM#230800) patients, the chitotriosidase activity is increased in about 600-fold compared with normal controls. Chitotriosidase is not only useful as a disease severity marker but also measures the effectiveness of the therapy in GD. However, chitotriosidase gene (CHIT1, 1q31-q32) mutations modify the plasma chitotriosidase levels and therefore introduce a degree of variability that can be misleading. The most well known cause of chitotriosidase deficiency is the common 24 bp duplication. Nonetheless, other mutations that occur in this gene also lead to altered catalytic properties. However, as suggested by Bussink and collaborators, slight modifications in assay conditions may help avoiding such problems.

In the present work we determined the frequency of two mutations which had appeared in a preliminary screening.