Spinal muscular atrophy (SMA) is a life-threatening condition characterized by the inability to move voluntary muscles as desired. The motor neurons responsible for exciting muscle contractions are deficient, and the loss of use of voluntary muscles causes them to atrophy. Characterized early in life, children with SMA show difficulty in early voluntary muscle activities such as crawling, sucking, imitating facial expressions, and breathing. There are three stages of SMA: SMA I for babies younger than six months, SMA II for babies between the ages of 6 and 18 months, and SMA III for all remaining babies. For many affected individuals, life expectancy depends on when symptoms began. . The longer it takes for SMA symptoms to appear in children, the more likely the individual is to live longer. Children with the first symptoms of SMA (SMA I) live an average of two years before dying. Patients with SMA II tend to live into early adulthood. SMA II and SMA III patients can potentially have the same average lifespan as treated healthy individuals. Diagnosis of the disease begins with visual diagnosis. Most people with SMA experience symptoms soon after birth or in early childhood. Babies may show difficulties with sucking, responding to external stimuli, mirroring facial expressions, breathing, and crawling within the first six months of life. Concerned parents go to the local doctor who recommends them to various specialists. A visit to the neurologist will require DNA testing for common neurogenetic disorders. As with many neurological diseases, there is no known cure for SMA. However, there are treatments to prevent the progression of SMA. SMA patients are subject to various… half of the article… SMN1 is located in region 1, band 3, subband 2 in the long arm of chromosome 13. SMN1 is flanked by two genes throughout the chromosome: NAIP and SERF1A. Originally cloned in 1995 by Lefebvre et al., the identified SMA locus was cloned into a yeast artificial clone (YAC). The YAC was then analyzed for possible sequence repeats. The SMN1 and 2,500 kb repeats were located within YAC of chromosome 5. Several single nucleotide polymorphisms (snps) are contained within SMN1, many of the snps are SMN family related snps: snp IDs VAR_005617, VAR_034803, VAR_034809 are just some of the 83 IL snps located within the SMN1 gene. In Drosophila, there is an SMN1 ortholog similarly called SMN and is located at 73A9-73A9 of the Drosophila genome. In humans there is an ortholog of Drosophila stasimon called TMEM41B, located in region 1, band 5, subband 4 in the short band of the chromosome 11.