Roles of SMN1 and SMN2 Genes
There are two SMN1 gene copies in our body. Each of them is passed down from the parent. On the other hand, there are many SMN2 gene copies. The SMN1 gene is responsible for the production of most SMN protein, whereas the SMN2 gene only plays a small part. When a mutation occurs in the SMN1 gene, it would increase the risk of inherited SMA in the babies. The number of SMN2 genes will affect the severity of the condition. If you have many SMN2 gene copies, they would still produce SMN protein, thus leading to mild cases. Nevertheless, when the number of SMN2 genes is low, symptoms can be more serious. [3]
