Spinal muscular atrophy (SMA) is a genetic condition affecting the spinal cord's motor neurons, which control muscle movement. When someone has SMA, their motor neurons gradually stop working, leading to muscle weakness and atrophy (shrinkage). This can cause difficulties with movement, such as trouble sitting up, walking, or breathing.
SMA is caused by a mutation in a gene that produces a protein called survival motor neuron (SMN), which is essential for the survival and function of motor neurons. There are several types of SMA, ranging from mild to severe, and the symptoms can vary depending on the type. In some cases, SMA can be life-threatening, mainly when it affects breathing and swallowing.
Without enough SMN, the motor neurons cannot work correctly and eventually die off. Around 94% of people with SMA have a specific type of genetic change called a homozygous deletion in a part of their DNA called exon 7 of the SMN1 gene.
Although there is no cure for SMA, treatments are available that can help manage the symptoms and improve the quality of life. These include medications, physical therapy, and assistive devices such as wheelchairs and breathing aids. Research is ongoing to develop new treatments and improve outcomes for people with SMA.
In a recent clinical trial, researchers investigated the effectiveness of newborn screening and access to disease-modifying therapies as an intervention for SMA. The study included 33 children with homozygous exon 7 deletions of the SMN1 gene who were either in a screening or comparator group.
The 2-year survival rate was 93% (14 of 15 children) in the screening group and 89% (16 of 18 children) in the comparator group. Among survivors, 11 (79%) of 14 children walked independently or with assistance in the screening group, compared with one (6%) of 16 children in the comparator group. Motor function improved significantly in the screening group over two years. The screening group also required less assistance with feeding.
In conclusion, the study found that newborn screening for SMA and early access to disease-modifying therapies can improve affected children's functional quality of life.