Sirolimus Therapy in Tuberous Sclerosis or Sporadic Lymphangioleiomyomatosis

To the Editor: Tuberous sclerosis is an autosomal dominant disorder characterized by hamartomatous growths in many organs and caused by inherited mutations of the TSC1 or TSC2 gene. Acquired (somatic) mutations of either gene occur within pathologic cells in patients with sporadic lymphangioleiomyomatosis. Renal angiomyolipomas occur in both disorders, resulting in substantial morbidity and mortality. 1 The proteins TSC1 and TSC2 regulate signaling through the mammalian target of rapamycin (mTOR) pathway to control processes including growth, cell-cycle progression, apoptosis, and autophagy. Constitutive activation of mTOR and its downstream targets occurs in lesions associated with tuberous sclerosis or lymphangioleiomyomatosis, suggesting that mTOR . . .