Amyotrophic Lateral Sclerosis: Literature Review

In the western world, Amyotrophic Lateral Sclerosis (ALS) is the third most common neurodegenerative disease, characterised by gradual paralysis that leads to death from respiratory failure. (Renton, et al., 2011). Frontotemporal Dementia (FTD), the second most common cause of young onset dementia, is categorised by the degeneration of the frontal temporal lobes in the brain which lead to personality and behavioural changes. (Fratta, et al., 2012). An increasing consensus proposes that ALS and FTD form part of a collection of neurodegenerative diseases share a mutual pathological background. (Majounie, et al., 2012). This review will first outline the neurodegenerative disease of Amyotrophic Lateral Sclerosis; the epidemiology and molecular genetics behind it. This will lead onto the specific genetic mutation of the C9orf72 gene which is known to cause the
(Kiernan, et al., 2011). Pathological features of the disease include pallor of the corticospinal tract due to motor neuron damage and the occurrence of ubiquitin-positive inclusions in living motor neurons. (Johnson, et al., 2010). Motor neurons are specialised nerve cells that can be found in the central nervous system (CNS) and are responsible for controlling muscle movement by carrying electrical impulses from the CNS to an effector (muscle or gland) tissue. Upper motor neurons are found in the cerebral cortex and brain stem and convey motor activity via a descending pathway to lower motor neurons. Located in the anterior grey column of the spinal cord, motor roots of spinal nerves and nuclei of cranial nerve cells in the brainstem, lower motor neurons act as a link between upper motor neurons and muscles. (Burke, 2007). The neurodegenerative disease of ALS involves the degradation of both upper and lower motor neurons, causing muscle atrophy throughout the