What is SMN2 gene?
The SMN2 gene provides instructions for making the survival motor neuron (SMN) protein. The SMN protein is found throughout the body, with highest levels in the spinal cord.
What chromosome is SMN2 on?
chromosome 5q13
The SMN2 gene is part of a 500 kb inverted duplication on chromosome 5q13. This duplicated region contains at least four genes and repetitive elements which make it prone to rearrangements and deletions.
What does SMN1 stand for?
SMN1 (Survival Of Motor Neuron 1, Telomeric) is a Protein Coding gene. Diseases associated with SMN1 include Spinal Muscular Atrophy, Type I and Spinal Muscular Atrophy, Type Iii.
How does SMN2 copy number influence severity of SMA?
Indeed, numerous studies show that the higher the SMN2 copy number, and so the larger the amount of full- length SMN protein produced, the milder the associated SMA phenotype and vice versa [17,18].
Where is SMN1?
This protein is one of a group of proteins called the SMN complex, which is important for the maintenance of specialized nerve cells called motor neurons. These cells are located in the spinal cord and the part of the brain that is connected to the spinal cord (the brainstem).
What does it mean if you have 2 copies of SMN2?
The number of SMN2 genes may vary, and a higher SMN2 copy number is associated with less-severe symptoms of spinal muscular atrophy. Nevertheless, the disease has a wide range of symptoms and it is difficult to predict severity based on the number of SMN2 copies alone.
What is the difference between SMA type 1 and type 2?
Infants with type 1 SMA usually die before their second birthday. Children with type 2 or type 3 SMA may live full lives depending on the severity of symptoms. People who develop SMA during adulthood (type 4) often remain active and enjoy a normal life expectancy.
What does SMA carrier mean?
What does it mean to be a carrier of spinal muscular atrophy? A carrier is a person who inherits one healthy copy and one faulty copy of the SMN1 gene. About 1 in 40 to 1 in 60 people are carriers of SMA. If both parents are carriers, they have a 1-in-4 chance of having a child with SMA.
What is SMA linked variant?
A linked variant, c.*3+80T>G, often associated with SMN1 gene duplication on the same chromosome, is tested. Presence of two SMN1 copies and linked variant increases risk of being silent carrier, especially in Ashkenazi Jewish individuals. SMN2 copy number is relevant only for affected individuals.
Is SMN2 a pseudogene?
A centromeric survival motor neuron (SMN2) pseudogene nearby on the same chromosome complicates genetic analysis, especially heterozygote prediction. The product of the SMN2 pseudogene typically skips exon 7. However, it now appears that the pseudogene can make a small amount of normal SMN protein.
What is the difference between SMN1 and SMN2?
The full-size protein made from the SMN2 gene is identical to the protein made from a similar gene called SMN1; however, only 10 to 15 percent of all functional SMN protein is produced from the SMN2 gene (the rest is produced from the SMN1 gene). Typically, people have two copies of the SMN1 gene and one to two copies of the SMN2 gene in each cell.
What is the SMN protein?
The SMN protein is found throughout the body, with highest levels in the spinal cord. This protein is one of a group of proteins called the SMN complex, which is important for the maintenance of specialized nerve cells called motor neurons.
How many copies of the SMN2 gene are there?
Typically, people have two copies of the SMN1 gene and one to two copies of the SMN2 gene in each cell. However, the number of copies of the SMN2 gene varies, with some people having up to eight copies. The more SMN2 gene copies a person has, the more SMN protein they produce.
What is smn2-associated spinal muscular atrophy (SMA)?
SMN2 undergoes a splicing event to exclude exon 7, resulting in a truncated and nonfunctional isoform of the SMN protein. A.H.M. Burghes, W.D. Arnold, in Spinal Muscular Atrophy, 2017 Milder SMN2 -containing SMA mice have also been generated; however, in all but two cases, these are on the very mild end of the expected phenotype.