A method of compiling a treatment reference table that indicates the responsiveness of one or more specific mutations of ±-Gal A to a specific pharmacological chaperone, the method comprising: analysing in vitro the response to the specific pharmacological chaperone in a host cell that has been transformed with a nucleic acid vector that encodes a first mutant ±-Gal A and compiling a table listing responsive and non-responsive mutant forms of ±-Gal A. The specific pharmacological chaperone is 1-deoxygalactonojirimycin or a pharmaceutically salt or ester and the first cell is HEK-293 MSR cell.