L'amyotrophie bulbospinale liée à l'X ou maladie de Kennedy : variations phénotypiques

Recessive X-linked amyotrophic spinobulbar muscular atrophy (SBMA) or Kennedy disease is a neuroendocrine disorder with a slowly progressive phenotype, caused by an expansion of a polymorphic tandem CAG repeat of the androgen receptor gene. Classical clinical hallmarks include onset in the third decade of life, weakness and wasting predominantly in proximal extremity muscles, variable weakness of bulbar muscles, abundant muscle fasciculations, sensory nerve action potential abnormalities and signs of androgen insensitivity such as gynecomastia and testicular atrophy. The diagnosis has been recently made easier by the availability of genetic testing but Kennedy disease is probably still underdiagnosed because of phenotypic variability. We report 11 new cases, of which seven had atypical initial manifestations presenting respectively with myasthenia, cramps and fasciculation syndrome, polyneuropathy, post-trauma monomelic neuronopathy, effort-dependent muscle intolerance and/or muscular dystrophy, with the aim to enlarge the phenotypic spectrum of the published series.