Hydrolysis of unsulfated alpha-L-iduronosidic linkages in dermatan sulfate. Monomer. Ubiquitous. N-glycosylation at Asn-372 contributes to substrate binding and is required for full enzymatic activity. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the glycosyl hydrolase 39 family.