IDUA and Scheie syndrome: To develop a Mucopolysaccharidosis type I (MPS I) treatment, a LSD characterized by a progressive accumulation of glycosaminoglycans due to the α-L-iduronidase (IDUA) gene mutation, they have included a miRNA sequence in a minicircle DNA vector with a tissue-specific promoter to obtain a slight improvement of its long-term expression respect to the same vector without the miRNA element.