[Mucopolysaccharidosis type VII: characterization of exonic point mutations and molecular heterogeneity]

We identified two different exonic point mutations causing beta-glucuronidase (beta G1) deficiency in three Japanese patients with mucopolysaccharidosis type VII. The beta G1-specific mRNA levels were normal. Sequence analysis of the full-length mutated cDNAs showed C-->T transitions, which resulted in a single Ala619-->Val change (case 1, a 8-year old female and case 2, a 24-year old male) and a Arg382-->Cys change (case 3, a 7-year-old female). Each of these two amino acid changes reduced the beta G1 activity of the corresponding mutant beta G1 expressed following transfection of COS cells with expression vectors harboring the mutated cDNAs.