Spinal muscular atrophy (SMA) is a generic, lethal condition characterized by an inability to will

800 WordsApr 23, 20194 Pages
Spinal muscular atrophy (SMA) is a generic, lethal condition characterized by an inability to will voluntary muscles as desired. The motor neurons responsible for exciting muscular contractions are deficient and loss of usage in voluntary muscles results in their atrophy. Characterized early in life, children with SMA exhibit difficulty in early voluntary muscular activities such as crawling, sucking, imitation of facial expressions, and breathing. Three stage of SMA exist: SMA I for children younger than six months, SMA II for children between 6-18 months of age, and SMA III for all remaining children. For many affected individuals, life expectancy depends upon the time in which symptoms began. The longer it takes for SMA…show more content…
Genetics of Spinal Muscular Atrophy In 1995 a French group of researchers discovered that SMA is autosomal recessive disorder due to loss of the survival motor neuron protein gene (SMN) (Lefebvre et al., 1995). Through experimentation the researchers discovered two copies of the SMN gene in chromosome five [chr 5q13.2]: telomeric and centromeric SMN copies. Experimentation proved that loss of the telomeric SMN (today known as SMN1) and not loss of its centromeric counterpart, SMN2, resulted in SMA. It took an additional six years for researchers to glimpse at the functions provided by SMN1. Meister et al. categorized the SMN1 protein an essential to promote correct assembly of U12 small ribonucleoproteins (snRNPs). In genetics, snRNPs are nucleic proteins responsible for the splicing of premature ribonucleic acid chains (pre-mRNA) derived from genes. Without correct splicing, mature ribonucleic acid chains (mRNAs) produce dysfunctional proteins when translated. In this case, splicing functionality of U12 - intron containing transcripts is lost, and because the transcript is wrongly coded, its translation will produce a functionless protein. Hence, loss of SMN1 results in an inability form U12 snRNPs splicing complexes, and reduced splicing functionality results in loss of U12 - intron splicing functionality (Patel and Steitz, 2003). Only recently (2012) did researchers

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