Genome Profiling and Potential Biomarkers in Neurodegenerative Disorders

Abstract

Neurodegenerative disorders (NDG) are incurable, progressive and debilitating conditions resulting from progressive degeneration and death of nerve cells. They are among the most serious health problems faced by modern society. Most of these disorders become more common with advancing age, including Alzheimer's disease and Parkinson's disease. The burden of these neurodegenerative diseases is growing inexorably as the population ages, with incalculable economic and human costs. According to the Global Burden of Disease Study, a collaborative study of the World Health Organization, the World Bank and the Harvard School of Public Health, dementia and other neurodegenerative diseases will be the eighth cause of disease burden for developed regions in 2020 [1, 2]. Also, according to the WHO, neurodegenerative diseases will become the world’s second leading cause of death by 2050, overtaking cancer [2]. True, such estimates and predictions need to be taken with caution, but they definitely confirm that neurodegenerative diseases are of an increasing public concern. Most NDG diseases are characterized by the aggregation of intracellular proteins. Majority of neurodegenerative disorders occur sporadically and are believed to arise through interactions between genetic and environmental factors. Only a small minority belong to familial forms where certain disease occurs due to a mutation of the gene coding for the abnormally aggregating protein. We differentiate many types of NDG disease, but the lines that separate one from another are often unclear. For instance, symptoms such as motor impairment and dementia may occur in many different types of NDG disease. Motor impairment similar to that seen in Parkinson’s disease is not enough to rule out other diagnoses, especially when both motor and cognitive impairment are present. At the time being, there is no such diagnostic test that can clearly indicate the presence, absence, or category of a NDG disease. Individual diagnosis is based on clinical evaluation of the symptoms, with the exception of monogenic NDG diseases, such as Huntington's disease (HD). HD is a single gene disorder and cause is invariably trinucleotide expansion mutation [3]. Definitive diagnosis of certain NDG diseases still relies on neuropathological evaluation. But it has been demonstrated that brain pathology can show marked overlap among the syndromes of age-related cognitive and motor impairment [4]. Also, previous research reports have shown that pathological markers do not always correlate optimally with clinical findings. Some individuals with extensive neuropathology may retain relatively