Motor neuron disease, or amyotrophic lateral sclerosis (ALS), is a condition of the central nervous system commonly known as Lou Gehrig’s disease. Affecting between 1 to 2 people in 100 000, this disorder is characterised by a progressive degeneration of motor neurons of which there is no known cure or treatment. Approximately ten percent of ALS cases are in their origin with the remaining majority are surmised to appear by chance. Geneticists have paid particular attention to this condition, focusing on the smaller number of hereditary cases in an attempt to infer upon its origins. Hereditary ALS is believed to be the key to understanding the noted random influence of ALS in every population. Recently a key breakthrough has been achieved that could possibly affirm the aforementioned hereditary basis of this condition through the location of an ALS gene.
Understanding the hereditary basis of common disorders is often undertaken through an examination of affected families and the inheritance of special DNA markers: restriction fragment length polymorphisms (RFLPs). Through the application of restriction enzymes and gel electrophoresis these variations in the DNA sequence of the genome are uncovered. These respective RFLPs are often not apart of the target gene, but their variation in sequence can often act as a marker for the close presence of the gene on the chromosome. Through the discovery of an RFLP that is frequently inherited with ALS, linkage to the specific gene of the disease can be uncovered tracing its specific chromosomal location.
Through the analysis of over 100 RFLPs scattered across a number of chromosomes and the ascertainment of an exclusion map ruling out regions of DNA that cannot contain the gene, a team from Northwestern University in Chicago has uncovered that chromosome twenty one contains an ALS gene. Furthermore, it was discovered that this gene did not cause ALS in all affected families, showing that at least one other defective gene must be present to result in the presence of variant forms of the condition. This also gives reason to the diagnosis of at least three forms of the disease.
Researches are now working on obtaining a greater knowledge of the specific function of the ALS gene. To obtain this knowledge it is first required to locate the exact position of the gene of the respective chromosome to enable sequencing of the DNA segment. It is of future focus to understand the function of the specific ALS genes to enable possible administrations of treatment plans for this condition.
James Nightingale
4200431
References:
http://www.newscientist.com/article/mg13117824.400-the-mystery-of-motor-neuron-disease-for-more-than-50-years-this-disease-has-baffled-epidemiologists-and-physicians-alike-but-the-mysterious-illness-may-be-about-to-yield-its-secrets-to-molecular-genetics.html
