Assay of whole brain extracts of WT or mutant mice for lysosomal α-L-fucosidase activity showed that the Gnptab −/− mice had a decreased level of this hydrolase that did not quite achieve significance (p = 0.0587) whereas the Gnptg −/− mice had a significant decrease in α-L-fucosidase activity (p = 0.0059) ( Fig. 9C ).
Although the Gnptg −/− mice showed a strong trend towards inferior performance at 12–14 months compared to WT littermate control mice with regard to the 60° inclined screen test, the differences were not significant like they were at the earlier time point ( Fig. 3H ).
These assays showed a small accumulation of amino sugars in the CNS of 12-month-old Gnptab −/− mice that did not reach statistical significance ( Fig. 9A ) but a significant increase in the level of fucose (p<0.05) ( Fig. 9B ).