Infantile-onset ascending hereditary spastic paralysis

Infantile-onset ascending hereditary spastic paralysis is a rare disorder characterized by progressive weakness and stiffness of muscles in the arms, legs, and face. This disorder damages motor neurons, which are specialized nerve cells in the brain and spinal cord that control muscle movement.

Initial symptoms of infantile-onset ascending hereditary spastic paralysis usually occur within the first 2 years of life. These symptoms include weakness of the legs, leg muscles that are abnormally tight and stiff, and eventual paralysis of the legs. People with infantile-onset ascending hereditary spastic paralysis are usually wheelchair-bound by late childhood or early adolescence. Over time, muscle weakness and stiffness travels up (ascends) the body from the legs to the head. By late childhood or early adolescence, arm and hand muscles are affected. Muscles in the neck and head usually weaken during adolescence; symptoms include slow eye movements and difficulty with speech and swallowing.

Infantile-onset ascending hereditary spastic paralysis is a rare disorder, with a small number of reported cases.

Mutations in the ALS2 gene cause infantile-onset ascending hereditary spastic paralysis.

The ALS2 gene provides instructions for making a protein called alsin. Alsin is abundant in motor neurons, but its function is not fully understood. Mutations in the ALS2 gene alter the instructions for producing alsin. As a result, alsin is unstable and decays rapidly. It is unclear how the loss of alsin protein damages motor neurons and causes infantile-onset ascending hereditary spastic paralysis.

Read more about the ALS2 gene.

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.