The rare genetic disease pulmonary lymphangioleiomyomatosis (LAM) occurs almost exclusively in women of childbearing age due to loss of function of the tumor suppressor gene tuberous sclerosis complex 2 (TSC2), a negative regulator of the mechanistic target of rapamycin complex 1 (mTORC1)2,3. The gene discussed is TSC2; the disease is lymphangioleiomyomatosis.