AR and Kennedy disease: Recently, an analysis of whole genome sequence data from large genomic datasets suggests a much higher-than-expected carrier frequency of the AR expansion, with a possible disease prevalence as high as 1/6887 males (or approximately 1/13 774 population).2 The massive underdiagnosis of spinal bulbar muscular atrophy is likely to be multifactorial and may be related to variable penetrance, expressivity and social determinants of health, among other factors.