Basal Cell Nevus Syndrome (Gorlin Syndrome)
The risk for childhood brain tumor, ovarian tumors, and skin cancer is increased with
basal cell nevus syndrome (also called Gorlin syndrome or nevoid basal cell carcinoma).
This is a rare autosomal dominant cancer genetic syndrome. Features linked to basal
cell nevus syndrome may include:
Development of more than 2 basal cell carcinomas (cancer of the outer layer of the
skin) before age 20
Cysts in the jaw
Characteristic facial appearance
Calcification of the falx (a variation in the appearance of the skull that can be
seen on X-rays)
Pits in the palms of the hands and soles of the feet
Macrocephaly (enlarged head size)
Rib or vertebral abnormalities
Increased risk of medulloblastoma (cancerous or malignant brain tumor) during childhood
Increased risk of cardiac or ovarian fibromas (noncancer or benign tumors)
Basal cell nevus syndrome is caused by changes in a tumor suppressor gene called PTCH1.
It's located on chromosome 9 or the SUFU mutation gene.
Molecular genetic testing of PTCH1 or SUFU is available on a clinical basis.
Tumor suppressor genes often control cell growth and cell death. Every person is born
with 2 copies of each tumor suppressor gene. One is inherited from the mother and
one from the father. Both copies of a tumor suppressor gene must be changed (mutated)
before a person's risk of cancer increases. With basal cell nevus syndrome, the first
mutation is inherited from either the mother or the father. This happens in 70% to
80% of cases. In 20% to 30% of cases, the first mutation is not inherited but the
affected person is born with the new mutation. Whether inherited or not, this first
mutation is present in all of the cells of the body from conception. It's called a
Whether a person who has a germline mutation will develop cancer and where the cancer
will develop depends on where (which cell type) the second mutation happens. For instance,
if the second mutation is in the skin, then skin cancer may develop. If it's in the
ovary, then ovarian cancer may develop. The process of tumor development actually
needs mutations in multiple growth control genes. Loss of both copies of PTCH1 is
just the first step in the process. Experts don't know what causes these additional
mutations. Possible causes include chemical, physical, or biological environmental
exposures (such as sunlight). Or there may be a chance of errors when cells copy themselves.
Some people who have inherited a germline tumor suppressor gene mutation may never
have cancer. This is because they never get the second mutation needed to knock out
the function of the gene and start the process of tumor formation. This can make the
cancer seem to skip generations in a family. But the mutation is still there. People
with a PTCH1 mutation may or may not have cancer. But they always have a 50% chance
of passing the mutation on to each of their children.
It's also important to remember that the gene responsible for basal cell nevus syndrome
is not found on the sex chromosomes. So mutations can be inherited from the mother's
side or the father's side of the family.
If you have a family history of cancers, discuss this with your healthcare provider.
Ask if you should be screened for a familial cancer syndrome. Also ask if you should
be screened for the development of certain tumors.