What chromosome is affected by spinal muscular atrophy?
SMA is inherited as an autosomal recessive genetic disorder and is associated with mutations in the survivor motor neuron 1 (SMN1) gene. SMN1 is located on chromosome 5 in the long arm (q) region.
What is SMN1 and SMN2?
The other versions are smaller and quickly broken down. 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).
What gene is mutated in spinal muscular atrophy?
Most people with spinal muscular atrophy are missing a piece of the SMN1 gene, which impairs SMN protein production. A shortage of SMN protein leads to motor neuron death, and as a result, signals are not transmitted between the brain and muscles.
What does the SMN1 gene do?
The SMN1 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 does it mean if you have 2 copies of SMN1?
If you have two copies of the healthy gene, it means that you have a reduced risk of being a carrier. If you have one healthy copy of SMN1, it means the other copy is faulty and you are a carrier. You could pass the faulty copy of the SMN1 gene to your child.
What is SMN1 variant?
An SMN1 variant, c. *3+80T>G, that is part of a haplotype associated with SMN1 duplication in silent carriers (two copies of SMN1 on one chromosome and no copies on the other), particularly in individuals of Ashkenazi Jewish descent, increases the likelihood that two copies of SMN1 are on the same chromosome.
Is SMN1 2 copies normal?
Carrier screening results for SMA are reported as the number of healthy copies of SMN1 a person has: If you have two copies of the healthy gene, it means that you have a reduced risk of being a carrier.