Distal spinal muscular atrophy type 1

Distal spinal muscular atrophy type 1 (DSMA1), also known as spinal muscular atrophy with respiratory distress type 1 (SMARD1), is a rare neuromuscular disorder involving death of motor neurons in the spinal cord which leads to a generalised progressive atrophy of body muscles.

The condition is caused by a genetic mutation in the IGHMBP2 gene and is inherited in an autosomal recessive manner. There is no known cure to DSMA1, and research of the disorder is still in early stages due to low incidence and high mortality rates.

Signs and symptoms

Usually, the first respiratory symptoms are shortness of breath (dyspnea) and paradoxical respirations which then escalate within the first few months of life to diaphragmatic paralysis. The symptoms of diaphragmatic paralysis come on very rapidly and without warning, and the patient is often rushed to a hospital where they are placed on a ventilator for respiratory support. Due to the severe nature of diaphragmatic paralysis, the patient eventually needs continuous ventilation support to survive. Continuous ventilation, however, may in itself cause damage to the anatomy of the lungs.

In addition to diaphragmatic paralysis, other issues may arise: as the name suggests, the distal limbs are most affected with symptoms of weakness, restricting mobility due to (near-)paralysis of the distal limbs as well as the head and neck. Also, dysfunction of the peripheral nerves and the autonomic nervous system may occur. Due to these dysfunctions, the patients have been shown to suffer from excessive sweating and irregular heartbeat.