Spinal and bulbar muscular atrophy (SBMA), also known as spinobulbar muscular atrophy, bulbospinal atrophy, X-linked bulbospinal neuropathy (XBSN), X-linked spinal muscular atrophy type 1 (SMAX1), and Kennedy’s disease (KD), is a debilitating neurodegenerative disease resulting in muscle cramps and progressive weakness due to degeneration of motor neurons in the brain stem and spinal cord. Similarly to Huntington’s disease, the spinocerebellar atxias and dentatorubral-pallidoluysian atrophy, SBMA is caused by an expansion of a glutamine repeat sequence. In SBMA, the glutamine repeat is in the androgen receptor. The disease is linked to chromosome X, which means that it is inherited through the mother.