Parkinson's disaese

Parkinson’s disease: a look at a novel biomarker, immunogenetic & mitochondrial studies

Virginia Thornley, M.D., Neurologist, Epileptologist
December 17, 2018
Parkinson’s disease is typically diagnosed through clinical evaluation. At times, it may be difficult to differentiate from other disorders if all cardinal features are not present. This looks at the literature to review biomarkers that may be helpful in evaluation of the diagnosis of Parkinson’s disease.
Novel serum marker LAG-3
One study correlates the serum marker LAG-3 lymphocyte activation gene 3  (LAG-3). It is thought to be related to the transmission of alpha-synuclein which could be connected to the degenerative process in Parkinson’s disease. Serum LAG-3 was found to be higher in the serum levels compared to patients with essential tremors and a control group that was sex and age matched. LAG-3 can potentially serve as a biomarker when the diagnosis is in question (1).
As the population ages, there is a proliferation of neurodegenerative disorders. Familial disorders account for a small portion of these about 5-10%. It is thought that there are genetic and environmental component to the familial types of neurodegenerative diseases. Gene variants are found on HLA (human leukocyte antigen) which code for MHL II (major histocompatibility complex class II) which is found in microglia which has an immunologic component. Microglia phagocytizes unnecessary proteins but also produces an inflammatory response. How the immune system responds to environmental factors resulting in neurodegenerative disease is a subject of research and needs to be elucidated further (2). 
The role of the mitochondrial dysfunction in Parkinson’s disease
Mitochondrial dysfunction and oxidative damage is found in the cells of patients with Parkinson’s disease. Mitochondrial abnormalities have been hypothesized to correlate with the pathophysiology of Parkinsons disease. Recent research has shown a tying of both genetic and environmental factors in relation to the pathophysiology of Parkinson’s disease. The PINK1 and Parkin gene are related to mitochondrial function and are present in Parkinson’s disease and the pathways involved with the  quality control in the mitochondrion. When oxidative stress is present and the cells cannot detoxify this can affect mitochondrial functioning which is the powerhouse of cells producing ATP or the energy source (3).
  1. Cui, S., Du, J.J., Liu, S.H., Meng, J., Lin, Y.Q., Li, G., He, Y.X., Zhang, P.C., Chen, S., Wang, G., Serm soluble lymphocyte activation gene-3 as a diagnostic biomarker in Parkinson’s disease: a pilot multicenter study,” Mov Disord 2018, Nov. doi:10.1002/mds.27569 (epub ahead of print)
  2. Aliseychik, M.P., Andreeva, T.V., Rogaev, E.I., “Immunogenetic factors of neurodegenerative diseases: the role of HLA Class II,” Biochemistry, 2018, Sep. 83(9):1104-1116
  3. Sato, S., Hattori, N., “Genetic mutations and mitochondrial toxins shed new light on the pathogenesis of Parkinson’s disease.” Parkinsons Dis. 2011; 2011:979231