ALS is a rapidly progressive and fatal disorder characterized by relentless impairment of motor function following the degeneration of the upper and lower motor neurons (LMN).1 In SBMA LMN degeneration, caused by an expanded cytosine-adenine-guanine (CAG) repeat in the first exon of the androgen receptor (AR) gene2 induces progressive disabling bulbar and limb weakness at a slower rate.3 At disease onset, ALS and SBMA may show similar symptoms, and distinguishing the 2 disorders is of paramount interest.4 Here, AR is linked to amyotrophic lateral sclerosis.