Although we detected highly increased levels of UCHL1 mRNA in MPS IIIB fibroblasts, another report demonstrated previously decreased levels of the gene product in several lysosomal storage diseases, including sialidosis, galactosialidosis, GM1-gangliosidosis, MPS IVA, MPS IVB, and Gaucher disease [45]. This evidence concerns the gene UCHL1 and mucopolysaccharidosis type 4B.