Mouse models of fukutin-related protein mutations show a wide range of disease phenotypes.

Dystroglycanopathies are characterized by a reduction in the glycosylation of alpha-dystroglycan (α-DG). A common cause for this subset of muscular dystrophies is mutations in the gene of fukutin-related protein (FKRP). FKRP mutations have been associated with a wide spectrum of clinical severity from severe Walker-Warburg syndrome and muscle-eye-brain disease with brain and eye defects to mild limb-girdle muscular dystrophy 2I with myopathy only. To examine the affects of FKRP mutations on the severity of the disease, we have generated homozygous and compound heterozygous mouse models with human mutations in the murine FKRP gene. P448Lneo+ and E310delneo+ mutations result in severe dystrophic and embryonic lethal phenotypes, respectively. P448Lneo+/E310delneo+ compound heterozygotes exhibit brain defects and severe muscular dystrophies with near absence of α-DG glycosylation. Removal of the Neo(r) cassette from the P448Lneo+ homozygous mice eliminates overt brain and eye defects, and reduces severity of dystrophic phenotypes. Furthermore, introduction of the common L276I mutation to generate transgenic L276Ineo+ homozygous and L276Ineo+/P448Lneo+ and L276Ineo+/E310delneo+ compound heterozygotes results in mice displaying milder dystrophies with reduced α-DG glycosylation and no apparent brain defects. Limited sampling and variation in functionally glycosylated α-DG levels between and within muscles may explain the difficulties in correlating FKRP expression levels with phenotype in clinics. The nature of individual mutations, expression levels and status of muscle differentiation all contribute to the phenotypic manifestation. These mutant FKRP mice are useful models for the study of disease mechanism(s) and experimental therapies.

Second international workshop for glycosylation defects in muscular dystrophies, 11-12 November, 2010, Charlotte, USA.

The second International Workshop for Glycosylation Defects in Muscular Dystrophies took place on November 11 and 12, 2010 in Charlotte, North Carolina, USA. The meeting was hosted by the Carolinas Medical Center with financial support from the Carolinas Muscular Dystrophy Research Endowment at the Carolinas HealthCare Foundation, the Muscular Dystrophy Association and funds raised by the "Jeans, Genes & Geniuses" event organized by Jane and Luther Lockwood. Since conducting the first workshop in May 2008, significant progress has been made in a subset of muscular dystrophies associated with defects in alpha-dystroglycan (α-DG) glycosylation. New findings on α-DG glycosylation and creation of novel animal models have expanded our understanding of the disease mechanism. The 2010 workshop focused on the following topics; (i) functional glycosylation of α-DG; (ii) animal models; and (iii) novel experimental therapies. The workshop brought together a total of 22 internationally renowned scientists and clinicians from US, UK, Denmark and Japan with active research and expertise in these areas. Overall, the workshop provided a unique opportunity to discuss the significance of recent progress, facilitate international collaboration, and identify new approaches to treat the disease.