PIK3C2A and Kennedy disease: We showed here that (1) respiratory failure in SBMA is not uncommon when analyzed through spirometry; (2) the decline of spirometric tests appears to be related to clinical deterioration and muscle loss; their longitudinal evaluation is crucial for managing patients with SBMA, particularly in regards to when to place PEG tubes; (3) MIP and MEP may detect respiratory insufficiency earlier than FVC, being likely related to muscle denervation; (4) CPK, transaminases, and spirometric data may be used as biomarkers for predicting response to treatments.