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Improving interpretation of variants in Sarcoglycanopathies

Muscular dystrophy is a group of diseases that cause progressive weakness and loss of muscle mass. Sarcoglycanopathies (SGPs) are a common but severe form of it, which affect hip and shoulder muscles. SGPs is an inherited disease with two mutations (variants) concurrently present in each of the chromosomes. Variants in four sarcoglycan (SG) genes can cause SGPs, named SGCA, SGCB, SGCG and SGCD. Currently, it is difficult to interpret a variant as pathogenic. Muscle biopsy or DNA sequencing is necessary for the patients to be diagnosed. Typically, variants predicted to produce no protein are easier to be interpreted as pathogenic, while missense, the most common type of variant in genes, are harder to interpret, leaving many suspected SGP patients without a definitive genetic diagnosis. The molecular feature of SGPs is the absence or reduced SG protein expression on the muscle cell membrane. We will use this feature to develop a high throughput functional assay and evaluate the pathogenicity of different variants. We will create a DNA library with all possible single nucleotide variants for an SG gene, then introduce them into cells. By flow cytometry, a technique used to detect the SG proteins on the cell surface, we will be able to predict the pathogenicity for each of the variants, especially difficult to interpret missense variants. This method will create a ‘look-up’ table to aid in the clinical interpretation of variants in patients with SGPs.
https://doi.org/10.55762/pc.gr.157030
Grantee: Shushu Huang, M.D.
Grant type: Development Grant
Award total: $210,000
Institution: Yale University
Country: Connecticut, United States