Spinal muscular atrophy also known as (SMA) is an autosomal recessive neuromuscular disorder caused by homozygous mutations of the SMN2 gene. Which means both parents must carry the gene mutation for it to be passed on to their children; however, rarely will either show symptoms. There is a 25% chance having a child that is affected. There are three forms of it, all depending on its severity. All patients with SMA will have at least one copies of the homologous gene (SMN2) which produces insufficient levels of the functional SMN protein. Currently there is no known cure for SMA is available. One possible therapeutic idea is based on attempts at increasing the amount of SMN protein produced by SMN2 genes. Recently, evidence has been provided that SMN2 mutation can be altered many different ways. The availability of participating patients to treat SMA has been an issue, but that doesn’t stop the search for a biomarker. This includes the availability of data on the history of the disease and other variables.
So far, different tools have been proposed as biomarkers in SMA. A biomarker can be simply explained as a molecule that is present or absent from a particular cellular type, which indicates whether a specific disease is there or not. The biomarkers that are used in SMA can be classifiable into two groups: instrumental and molecular. The molecular biomarker consists of the SMN gene products in dosages, either transcripts molecules or protein molecules. And the instrumental biomarkers are the Compound Motor Action Potential, the Motor Unit Number Estimation, and the Dual-energy X-ray absorptiometry. Unfortunately, neither of these biomarkers is even close to being available currently for this specific gene.
The authors stated that since the science community deiced to do clinical studies on SMA then the development of biomarkers must be created to further the understanding of this disease. Also since the topic was brought up none of the biomarkers that were used in this experiment meet the “gold standard” quality. These biomarkers just weren’t the most suitable and reliable measures for SMA. Even though some of the results came back positive for the substances that were being tested for, there are still several crucial issues which should be resolved before that biomarker is even considered being available for SMA research.
The biomarker technology is what is being used in this experiment. The SMN transcripts are the only potential molecular biomarker available. The SMN transcript measures the protein in peripheral blood. There are other possible variations of SMN transcripts/protein levels as evaluated in leukocytes may not reflect the real effect of pharmacological treatment in target tissues, like the spinal cord and, possibly, skeletal muscle. Other tissues are being considered as biomarkers, such as skin tissue or muscle biopsies. Muscle biopsies are simply muscle tissue, which has been removed for another use. Also preclinical studies and double-blind, placebo-controlled studies have been mentioned as approach for treatment. Preclinical studies on SMA positive animal models can provide information on some issues. And a double-blind, placebo- controlled studies are crucial to evaluate the effectiveness of specific biomarkers. Even though there has not been a lot of success with the search of a biomarker for SMA, the search doesn’t stop until that day.
-C. Freycinet
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