4-Methylumbelliferyl-α-L-Iduronide is a common substrate for α-L-iduronidase catalytic activity.

Using 4-Methylumbelliferyl-α-L-Iduronide as a substrate, α-L-Iduroinde activity was measured in leukocytes and lymphoblasts obtained from patients with α-L-Iduronide acid deficiency and obligate heterozygotes for the disease. α-L-Iduronide in leukocytes and lymphoblasts from patients and controls was completely different. However, an overlap in activity values ​​was observed in obligate heterozygotes and controls. 4-Methylumbelliferyl-α-L-Iduronide activity has a higher sensitivity, a simpler detection procedure, and a shorter latency period.[1]