APCl1307K:     Diagnosis    

  
Genetic/DNA Testing

There is a gene test to look for this inherited gene mutation. 
  

Figure 4. Chromosome 5 showing APC I1307K

Anyone who is thinking about having a gene test must receive genetic counseling. This is required because there are many issues to consider before testing. Genetic information can affect different people in many ways.

This gene test is performed at the Johns Hopkins University Pathology Molecular Diagnostics Laboratory in Baltimore, Maryland, and at a few other laboratories in the country. The cost of this gene test may vary. Genetic counseling may be required and would be an additional cost. Some insurance companies will pay for genetic counseling and testing, others will not. People who are thinking about having a gene test done should check with their insurance company before making a final decision.
A negative gene result can mean that there is a 99% chance that an individual does not carry the gene mutation. This person may still have a mutation in another gene that causes hereditary colorectal cancer. Other risk factors can be assessed during genetic counseling, where family history, lifestyle, and other issues may be discussed.

A positive gene result can mean that a person has an estimated 10–20% risk of developing colorectal cancer in his or her lifetime. The APC I1307K test results are 99% accurate. This is only a gene test; it does not detect the presence of cancer or polyps.

Who Should Consider Testing for the APC I1307K Mutation?
Any person of Ashkenazi heritage who has a personal or family history of colorectal cancer or colorectal polyps may wish to consider testing. A family history means having at least one close family member with colorectal cancer or polyps. Ashkenazi Jews without a family history of colorectal cancer may still wish to obtain genetic counseling to learn the value of gene testing in their own unique circumstances.

Genetic counseling is available, and recommended, for individuals who may have the APC I1307K mutation, and their family members. Genetic counselors will explain the inheritance pattern of APC I1307K, discuss which family members are at risk for developing the condition and provide necessary information regarding genetic testing. Counseling services are available through genetic and oncology departments in many hospitals. To make an appointment with a member of the Johns Hopkins professional medical team or to speak with someone at the Colorectal Cancer Risk Assessment Service, please call (410) 614-LIFE (5433). Also, it is recommended that APC I1307K families contact registries for access to resources and for help with identification of at-risk family members.

What Should You Do if You Receive a Positive Gene Test Result?
It is important to detect colon polyps or cancer early. Routine screening is the best way to do this. At this time, experts recommend the following:

Persons with a positive test result, who do not already have colon cancer or polyps, should have a routine colonoscopy every 2 years beginning at age 35 OR 5–10 years before the earliest age at which colon cancer or polyps occurred in the family, whichever is younger.

Patients with a personal history of colon cancer or polyps should have a routine colonoscopy every 2 years, or more often at the recommendation of their doctor.

Relatives of people testing positive for this gene mutation should consider counseling and testing as well.

Genetic Testing and Insurance
With any gene test there is a risk of insurance (life or health) or employment discrimination. At this time there are federal laws that offer protection against discrimination of people who have medical insurance through a group health plan. Some states have laws to protect people, but the laws on insurance and employment discrimination vary from state to state. The Americans with Disabilities Act may protect people with a positive gene test from discrimination in the workplace. These issues can be discussed with a genetic counselor.

Digital Rectal Examination
This is a painless examination of the rectal area. The physician inserts a gloved, lubricated finger into the rectum to gently feel for any abnormalities.  
 
 

The sigmoidoscope is inserted into the anus through the rectum and into the large intestine. Using the sigmoidoscope, the doctor can see whether polyps or cancer are present (Figure 16). At the time of sigmoidoscopy, a biopsy forceps may be inserted through a channel of the scope to remove a small sample of tissue for microscopic examination. Sometimes it is necessary for the doctor to introduce air into the sigmoid colon to improve visibility. Most patients feel a little cramping or discomfort when having a flexible sigmoidoscopy.  
 

Figure 5. Position of the sigmoid scope in the colon.

Figure 6. Patient positioning for sigmoidoscopy and colonoscopy.

A colonoscopy is an examination of the rectum and the entire colon. It is performed with a lighted, flexible, hollow tube, which is slightly larger in diameter than an enema tube. Colonoscopy permits the doctor to see much farther into the bowel than sigmoidoscopy. The colonoscope allows the doctor to see whether polyps or cancer are present.  
 

Figure 7. Position of the colonoscope in the colon for colonoscopy.

A sedative is given before a person undergoes colonoscopy. Many people sleep through the whole procedure and feel little or no discomfort. Occasionally, the insertion of air during the procedure may cause the same kind of discomfort as gas pain.

If a polyp is found, removal through the colonoscope may be sufficient, although surgery may be recommended for some patients.  
 

Figure 8. Endoscopic view of biopsy forceps

Figure 9. Patient positioning and set up for a barium enema x-ray.

 
 
Make an appointment today - call (410) 955-4166.