What Causes LAM?

Researchers do not know what causes LAM, or why it affects mostly women. They have recently discovered that LAM has some of the same features as another rare disease called tuberous sclerosis complex (TSC). This discovery has begun to provide some valuable clues about what causes LAM.

The common features of LAM and TSC are:

• People with TSC develop growths in their kidneys that are the same as the angiomyolipomas that many people with LAM develop in their kidneys.
• About 1 out of every 3 women who has TSC develops cysts in her lungs that are the same as the ones women with LAM develop in their lungs.

TSC is a genetic disease. It is caused by abnormalities, or defects, in one of two genes. These genes are called TSC1 and TSC2. Normally, they make proteins that control the growth of the cells in the body. In people with TSC, the genes are abnormal, and the proteins that they make cannot control cell growth and movement.

LAM patients also have abnormal versions of the TSC1 and TSC2 genes, and researchers have discovered that these genes play a role in the development of LAM. More research on the TSC genes and the proteins that they make should shed new light on the causes of LAM.

Since LAM mostly affects women in their mid-forties, many doctors think that estrogen also plays a role in causing LAM.