GLA and Fabry disease: The fibroblasts derived from FD patients with GLA IVS4 + 919G>A mutation—the most common type of GLA mutation in Taiwan—in addition to the alternative splicing that introduces a 57-nucleotide (nt) intronic sequence to the α-Gal A transcript from intron 4 of the gene, have been identified [27,28,29] as expressing a lower level of endogenous GLA enzyme activity and protein expression compared with the fibroblasts derived from healthy subjects (Figure 4A).