This project merges basic science with patient-relevant translational research because it identifies the causes of rare genetic diseases that impair protein N-glycosylation. Today, 39 genes are known to cause Congenital Disorders of Glycosylation (CDG), but we know that many CDG-causing genes remain undiscovered. This proposal uses a new, unbiased, forward-reaching, functional approach to identify these new genes.
The Specific Aims build a bi-directional bridge between fundamental science and genetic defects in patients today. It will identify new genes to guide and inform physicians in their diagnosis of tomorrow's CDG patients in the sub-$1000-genome era. CDGs affect every organ system with a breath-taking array of variable clinical presentations that cross every medical specialty. Clinical presentations do not identify the gene, however, nearly all current CDG patients have an abnormal serum transferrin (Tf) glycosylation biomarker. There is no Tf-like cellular biomarker that can be used to assess glycosylation or complement candidate genes in suspected glycosylation-deficient patients. To fill this void, we constructed an ER-retained GFP with an N-glycosylation site (Glyc-ER-GFP) that allows fluorescence only when that site is unoccupied. This provides a highly sensitive N-glycan-biosensor for cells with impaired glycosylation: They glow. This novel cellular biomarker can identify new N-glycosylation genes by screening a well-established human genome-wide siRNA knockdown library for cells that glow. The known CDG genes serve as positive controls for the screening. Secondary glycosylation biomarkers and biochemical assays can confirm the novel gene's involvement in N-glycosylation. This approach has immediate and long-term payoffs. The functional glycosylation assay can identify genes to query today's CDG patients with unknown defects. In the future, subjects in the whole exome (genome) sequencing pipeline who show mutations in these genes will know it impacts the N-glycosylation pathway. The newly discovered genes will also expand the dimensions of our current understanding about protein glycosylation.

Agency
National Institute of Health (NIH)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21HD076358-02
Application #
8706197
Study Section
Therapeutic Approaches to Genetic Diseases (TAG)
Program Officer
Krotoski, Danuta
Project Start
Project End
Budget Start
Budget End
Support Year
2
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Sanford-Burnham Medical Research Institute
Department
Type
DUNS #
City
La Jolla
State
CA
Country
United States
Zip Code
92037