What is spinal muscular atrophy (SMA)? It is an inherited disease that affects approximately 1 in 10,000 infants born in the United States each year. There are four types of SMA, which can cause the muscles to function improperly and become smaller and weaker over time. Visitors to this site, which was created by researchers at Cold Spring Harbor Laboratory, should start their journey here by clicking on the What is SMA? section. Here they can watch Dr. Darryl De Vivo provide an overview of the four types of SMA and then look through video clips from other professionals who provide additional insights into the genetics behind SMA. Moving on, the SMA Science area provides high-quality animations that illustrate the various processes involved with the SMN gene (mutations of which are responsible for SMA) and protein splicing. Visitors can also click on the SMA Therapies to learn more about what's being done for people living with SMA, along with potential new treatments.