What is the cause of LAM?

The cause of sporadic LAM is at present unknown. We know that it is not inherited and it is not passed on to children. We also know that one of two proteins (called tuberin and hamartin) are abnormal in LAM tissue. This is due to mutations in the genes responsible for these proteins. The proteins act as a brake on the growth of LAM cells and when they are abnormal there is excessive growth of these cells. Why this should happen is not clear, however, but stopping the growth of these cells is the main focus of research.