The observations of Kim et al. raise several questions. Why is PMA more common in men, whereas bulbar-onset ALS is more common in women? Why does PMA progress more slowly than the classic form of ALS?

Spinal bulbar muscular atrophy (SBMA) causes a loss of motor neurons in the spinal cord and brainstem. It mainly affects facial and swallowing muscles and the muscles in the arms and legs.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that is marked by fasciculation, spasticity and progressive weakness of muscles, and results in difficulty speaking ...