Juvenile primary lateral sclerosis
Juvenile primary lateral sclerosis is a rare, progressive disorder caused by damage to motor neurons, leading to muscle weakness and spasticity.
Overview
Juvenile primary lateral sclerosis is a rare disorder characterized by progressive weakness and tightness (spasticity) of muscles in the arms, legs, and face. These features are caused by damage to motor neurons, which are specialized nerve cells in the brain and spinal cord that control muscle movement.
Symptoms
Symptoms typically begin in early childhood and progress slowly over many years. Early signs include:
- Clumsiness
- Muscle weakness and spasticity in the legs
- Difficulty with balance
As the condition progresses, spasticity spreads to the arms and hands. Affected individuals may also develop:
- Slurred speech
- Drooling
- Difficulty swallowing
- Inability to walk
Causes
Most cases are caused by mutations in the ALS2 gene, which provides instructions for making a protein called alsin. Alsin is abundant in motor neurons, though its exact function is not fully understood. Mutations lead to unstable or non-functional alsin, which is believed to damage motor neurons, though the exact mechanism remains unclear.
Inheritance
When caused by mutations in the ALS2 gene, juvenile primary lateral sclerosis is inherited in an autosomal recessive pattern. This means both copies of the gene in each cell have mutations. Parents of an affected individual each carry one copy of the mutated gene but typically do not show signs or symptoms of the condition.