A single-base-pair deletion in the beta-glucuronidase gene accounts for the phenotype of murine mucopolysaccharidosis type VII.
Murine mucopolysaccharidosis type VII is a heritable disease caused by a spontaneous mutation, gus(mps), closely linked to the beta-glucuronidase structural gene on chromosome 5. Mice homozygous for the mutation have a > 200-fold decrease in beta-glucuronidase mRNA levels and virtually no enzyme activity detectable by a sensitive fluorometric assay. Approximately 20 kb of genomic DNA containing the beta-glucuronidase gene Gus and > 2 kb of 5' and 3' flanking sequences were cloned from both a gus(mps)/gus(mps) mouse and a +/+ mouse of the progenitor strain. Restriction enzyme digests containing DNA fragments 20-400 bp in length were generated from each of the two Gus alleles and then compared by using nondenaturing polyacrylamide DNA-sequencing gels. This method rapidly identified a large number of restriction sites and was sensitive enough to detect a restriction fragment length variation resulting from a 1-bp deletion in the gus(mps) allele. DNA-sequence analysis of the mutant genomic fragment showed that the 1-bp deletion created a frameshift mutation within exon 10. Insertion of the deleted nucleotide by oligonucleotide site-directed mutagenesis restored function to the corrected mutant gene when transfected into gus(mps)/gus(mps) fibroblasts. We concluded that the frameshift mutation, which introduces a premature stop codon at codon 497 in exon 10, accounts for the molecular, biochemical, and pathological abnormalities associated with the gus(mps) phenotype.
Sands
M S
MS
Jackson Laboratory, Bar Harbor, ME 04609.
Birkenmeier
E H
EH
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D005091:Exons / Q000235:genetics; D016368:Frameshift Mutation / Q000235:genetics*; D016678:Genome; D005966:Glucuronidase / Q000235:genetics*; D051379:Mice; D008817:Mice, Mutant Strains; D008969:Molecular Sequence Data; D016538:Mucopolysaccharidosis VII / Q000201:enzymology / Q000235:genetics* / Q000662:veterinary*; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D012150:Polymorphism, Restriction Fragment Length; D015183:Restriction Mapping; D012376:Rodent Diseases / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection
D005966:Glucuronidase