Table 1. GAA protein and activity variation in transient transfected HEK293 cells.

	M110	C110	C95	C76	M%	C%	Class
GAA-Trp746Cys	3,4	3,4	3,4	3,4	6.4	28.5	D
GAA-Arg463fs	1,1	3,4	3,4	3,4	1.1	8.3	C
GAA-Trp746Cys/ Arg463fs	1,1	2,4	2,4	2,4	0.5	2.5	B

Note: M110, C10, C95, and C76 stand for the various molecular forms of GAA during posttranslational modification and were visualized by western blot in Figure 5A. The numbers refer to the severity scaling [22]. Class A mutations are very severe, class B mutations are potentially less severe, class C mutations are mild, and class D mutations are probably nonpathogenic. M% stands for the percentage of GAA activity in the culture medium and C% for the percentage of GAA activity in the cells as compared to wild-type GAA activity.