Recent studies have provided some insight for the possible causes of the familial type of amyotrophic lateral sclerosis (FALS). This disease occurs only in 10% of the known cases of ALS with the sporadic, non-hereditary form being predominant [7, 9]. ALS in general has an occurrence of 0.4 to 1.8 per 100,000 live births . ALS has been called Lou Gehrig’s disease, Charcot’s disease and motor neuron disease in other literature . ALS is a neurodegenerative disease of upper and lower motor neurons that can manifest in such a way that it can be misdiagnosed. Such areas include respiratory muscles with initial diagnosis of asthma, or even psychological problems that appear as a dementia . The primary manifestations are not
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Mutations in the glutamate receptors have also been studied. Glutamate is known to be a powerful neurotoxin . The GluR5 gene, located on chromosome 21, codes for the glutamine receptor N--Methyl D-Aspartate (NMDA) which is also located near the locus for the familial form of ALS. This includes it as a possible causative agent for ALS, as well [3,5,6]. Clear delineation’s between motor neuron disease, Parkinson’s disease and dementia are hard to make . The definition of ALS includes degeneration of upper and lower motor neurons. Sometimes dementia may be the result of ALS and this may be misdiagnosed.
FALS is considered an autosomal dominantly inherited trait. Due to the rare occurrence, few twin studies have been made; however, there has been a set of identical twins found in which one was diagnosed with ALS and the other was not . There can be a problem in reviewing FALS due to under-reporting and incomplete family histories. Family studies are as extensive as possible and even involve reviewing death certificates. More in depth studies have involved the investigation of gene defects. Interfamilial and intrafamilial heterogeneity have been studied .
The SOD1 gene of chromosome 21 has been proposed as the causative agent for several cases of FALS [ 3, 4,11]. The SOD gene encodes the peptide superoxide dismutase . FALS has been linked to the long arm of