What does it mean to have 2 copies of SMN1 gene?
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 mutation?
A mutation in the SMN1 gene leads to a deficiency of a motor neuron protein called SMN, which stands for “survival of motor neuron.” As its name implies, this protein is responsible for gene expression necessary for normal motor neuron function.
What does 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.
How many copies of SMN1 is normal?
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.
Do both parents have to carry the gene for SMA?
An individual must inherit two non-functioning SMA genes – one from each parent – to have symptoms of SMA. If both parents are carriers there is a one in four (25 percent) chance that both will pass on the non-functioning gene, which would result in a pregnancy affected with spinal muscular atrophy.
Is 3 copies of SMN1 normal?
Second, the copy number of SMN1 can vary on a chromosome; we have observed that approximately 5% of the normal population possess three copies of SMN1. It is therefore possible for a carrier to possess one chromosome with two copies and a second chromosome with zero copies.
How common is SMN1 gene?
In US Whites, ∼1 in 35 are SMA carriers. SMA is caused by the homozygous loss of survival motor neuron 1 (SMN1) gene function due to a deletion or possibly to a gene conversion event in ∼95% of cases;3 the remaining 5% of patients have intragenic mutations that inactivate the gene.
What does SMN1 stand for?
GeneCards Summary for SMN1 Gene SMN1 (Survival Of Motor Neuron 1, Telomeric) is a Protein Coding gene. Diseases associated with SMN1 include Spinal Muscular Atrophy, Type Iii and Spinal Muscular Atrophy, Type I.
Can you have kids if you have SMA?
Unlike a genetic disease such as Down syndrome, age has nothing to do with whether you could have a baby with SMA. Couples of all ages can be SMA carriers and have a baby with SMA.
What does it mean to be a silent carrier of SMA?
“Silent carriers, or 2+0 carriers, comprise 3.7% of SMA carriers. A silent carrier is an individual who has 2 SMN1 copies in cis, and current technologies are unable to detect because it cannot identify the haplotype phase.