Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is one type of a group of conditions known as spinal muscular atrophies (SMAs), which are inherited disorders that cause a child to lose a specific type of cell in their spinal cord (motor neurons) and a part of their brain that is connected to the spinal cord (brain stem). Without these important parts of the brain and spinal cord, an affected child loses control of muscle movement, has muscle weakness, and loses muscle tissue (atrophy). In addition to muscle weakness and atrophy, a major complication of SMARD1 is breathing problems. During the first few months of an affected baby’s life, the muscle between the abdomen and chest cavity (diaphragm) will become so weak that it can no longer work (paralysis). This causes a sudden inability to breathe (respiratory failure). When this happens, life long breathing support with a machine (ventilator) is needed.
In addition to the respiratory failure, affected babies will develop weakness in the muscles that are furthest from the center of the body (distal), such as the hands and feet. This weakness then spreads to all the other muscles in the body. Children with SMARD1 typically have delays in motor milestones, such as sitting, standing, or walking. Other issues may include an abnormal curve to the spine (scoliosis), and heart beat irregularities (arrhythmia).
SMARD1 is caused by a change (mutation) in the IGHMBP2 gene and is inherited in an autosomal recessive way, meaning that mutations in both copies of the gene are needed to cause the condition. SMARD1 is considered in a baby with respiratory failure and muscle weakness. Genetic testing is used to confirm the diagnosis. The goal of treatment is to reduce the complications of the disease, including a ventilator to help with breathing. If your child has been diagnosed with SMARD1, talk to your doctor about all current treatment options.