Graduate Student University of Kentucky College of Medicine
Katherine Donohue (University of Kentucky College of Medicine)| Maya Abul-Khoudoud (University of Kentucky College of Medicine)| Craig Vander Kooi (University of Kentucky College of Medicine)| Matthew Gentry (University of Kentucky College of Medicine)
Lafora disease (LD) is an autosomal recessive neurodegenerative disease. Patients develop normally as children, and are typically diagnosed during adolescence, when the disease presents as a form of progressive myoclonus epilepsy. The disease then progresses rapidly, with patients experiencing seizures of increasing severity and frequency, along with loss of muscle control and neurodegeneration, leading to death within 10 years. Multiple therapies are in development for LD patients, however, recent studies suggest that early detection will be critical for effective treatment of LD patients.
It is known that patients with Lafora Disease have mutations in either Epilepsy, Progressive Mycolonus 2A (EPM2A), or Epilepsy, Progressive Mycolonus 2B (EPM2B), which code for the proteins laforin and malin, respectively. Laforin is the only known mammalian phosphatase that can remove phosphate from glycogen, and malin is an E3 ligase that has been shown to ubiquitinate enzymes involved in glycogen synthesis and degradation. Together, these proteins play critical roles in regulating glycogen metabolism. Disease causing mutations occur throughout each protein, suggesting multiple roles for both laforin and malin in glycogen regulation. Given the diversity of disease-causing mutations in these proteins, it is challenging to determine if a mutation will be deleterious prior to the onset of epilepsy in the patient.
In order to effectively treat LD patients, disease-causing mutations will need to be identified prior to the onset of symptoms, while the patient still shows normal development. Therefore, physicians need a reliable method for determining mutation pathogenicity. Here, we present a biochemical pipeline for laforin to characterize newly identified SNPs and determine pathogenicity. Through the integration of multiple techniques including differential scanning fluorimetry, phosphatase activity assays, and HDX analysis, our lab has characterized the impact of SNPs on laforin function. This pipeline will allow physicians and patients to obtain personalized diagnoses of Lafora Disease prior to the onset of symptoms.
Support or Funding Information
This work was supported by the National Institutes of Health [P01 NS097197 to M.S.G., R35 NS116824 to M.S.G.]