Gardner’s syndrome is caused by a mutation of the adenomatous polyposis coli (APC) gene, which is passed on through genetics. It can be passed on from either the father or mother. There are two copies of each gene in every cell, so even if a patient’s mother has Gardner’s syndrome, only one copy of the gene will be affected, and there is therefore around a 50 percent chance that the affected version of the APC gene will be passed on to the patient.
Gardner’s syndrome is a form of familial adenomatous polyposis (FAP), which causes several non-cancerous tumors to grow on the inside of the intestinal tract. Cells within the intestinal lining combine and form growths, and sufferers usually have multiple adenomatous polyps in their colon by their mid-30s. The presence of the condition, especially if it is left untreated, leads to a significantly increased risk of developing colorectal cancer or other cancers such as stomach cancer.
The syndrome is passed on through the genes, so understanding this relationship is vital to understanding how the genetic mutation can be passed on. If someone suffers from the syndrome, he will have one mutated version of the APC gene, and one un-mutated version. The chance of the mutated gene being passed on to his children is only 50 percent. If both parents have a faulty version of the APC gene, there is only a 25 percent chance that the child will receive both faulty genes.
The chances of getting Gardner’s syndrome are low because the condition is considered to be very rare. The chances of both parents having the condition are very small if they are not related. However, 30 percent of people who have FAP actually have a new gene mutation, meaning there is no family history of the condition. FAP is the larger condition of which Gardner’s syndrome is a sub-type, so there is a possibility that non-genetic development of the condition is possible.
People who have several colon polyps and other tumors such as osteomas, which are bone tumors usually found on the jaw, are generally tested for Gardner’s syndrome or FAP. To test for the condition, a blood sample is taken and examined for the mutation of the APC gene. If a mutation is found within one family, the chance of close relations such as brothers and sisters having the condition is also 50 percent, meaning that they will need to be tested.