A deletion causing spontaneous fracture identified from a candidate region of mouse Chromosome 14
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Map-based cloning is an iterative approach that identifies the underlying genetic cause of a mutant phenotype. However, the classic protocol of positional cloning is time-consuming and labor-intensive. We now describe a genome sequence–based cloning approach that has led to localizing the underlying genetic cause of spontaneous fractures (sfx) in a mouse model. The sfx/sfx mouse is characterized by a spontaneous femoral fracture seen around 6 weeks of age, which represents a new mouse model for bone fragility. Genetic studies indicate that the phenotype of sfx/sfx mice is caused by an alteration at a single locus that is roughly mapped onto the central region of mouse Chromosome 14. Using our strategy of combining mouse genome resources and high-throughput technology, we discovered a deletion of all 12 exons in the gene for L-gulonolactone oxidase (LGO), a key enzyme in the synthesis of ascorbic acid. We have also examined the expression of LGO and found no expression of LGO in sfx mice while the LGO expresses in several tissues of normal mice. Our data demonstrated the feasibility to positionally clone the mutated gene from a non-fine-mapped locus, which has applicability to the positional cloning of genes from many other animal models, as their genome sequences are sequenced or will be sequenced soon.
KeywordsPositional Cloning Scurvy Microarray Screening Obvious Candidate Gene Positional Cloning Approach
Funding for WKG came from the Center of Excellence for Genomic and Bioinformatics, Center of Excellence for Diseases of Connective Tissues at the University of Tennessee Health Science Center, and the Veterans Administration Medical Center, Memphis, TN; and from NIH (AR51190). Funding for WGB was from NIH AR43618 and CA43619 (CORE grant, The Jackson Laboratory). Funding for YT and DG came from NIH 5U01MH61971. We thank Dr. Vicki Park for providing human DNA samples and information on polymorphism. We thank Dr. Syamal K. Bhattacharya for measuring of mineral contents of the bones.
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