Tuesday, January 27, 2015
Li-Fraumeni Syndrome Germline
I just have a couple Li-Fraumeni Syndrome questions left if that`s ok. If the p53 germline mutation is in all the cells, why don`t people get ALL the varieties of cancer? And why would sarcoma always occur? I`d think they`d be evenly spread all over. (Just curious now.)
Answer #1: Why don`t people get all the varieties of cancer? The second mutation, not the germline p53 mutation, is what determines where and what kind of cancer may develop in a person with LFS. That second, or somatic mutation, occurs by chance and may also require other genes in the same cell to have been previously altered. There is a lot of randomness about all this. As such, the cancer may be in a wide variety of locations and from a wide variety of types.
Answer #2: Why does sarcoma always occur? Sarcoma occurs somewhere in the family history in LFS. It doesn`t have to occur in each person with Li-Fraumeni syndrome.
Carcinoma is the most frequent kind of cancer. A cancer which starts from the epithelial cells (the cells forming the linings of both the inside and outside of the body) is called "carcinoma." Carcinomas form from the skin, the lining of the digestive tract from the mouth to the rectum, the lining of the bronchi and the lungs, and the lining of the ducts inside glands (breast, pancreas, adrenal, etc.).
Sarcomas are less common and form from a different type of cell. They form from the layer beneath the epithelial cells -- the connective tissue or mesenchyme. These cells don`t actively divide as much and, as such, are not as likely to turn into cancer. The presence of sarcomas in LFS indicates the widespread "total body" nature of the germline mutation in p53.
Judith A Westman, MD
Associate Professor, Clinical Internal Medicine, Pediatrics and Medical Biochemistry
College of Medicine
The Ohio State University