Infantile-onset ascending hereditary spastic paralysis (IAHSP) is a rare, early-onset autosomal recessive motor neuron disease associated with mutations in the ALS2 gene [1], which is also responsible for other motor neuron diseases (MNDs), such as ALS type II [2] and juvenile primary lateral sclerosis (JPLS) [3]. The gene discussed is ALS2; the disease is infantile-onset ascending hereditary spastic paralysis.