1. Lynch Syndrome or Hereditary Non-Polyposis Colorectal Cancer (HNPCC)

2. Lynch Syndrome- A Genetic Disease
Most colon cancers occur by chance. Some colon cancers are inherited.
Lynch Syndrome is a genetic condition which increases one’s risk of getting colon and other cancers.
2-5% of patients with colon cancer have Lynch Syndrome.
2% of women with endometrial cancer have Lynch Syndrome.

3. Genes Determine Our Characteristics
The human body is made of small living units called cells.
Cells in the body contain millions of genes.
Genes are the basic
structural and functional
units of heredity.
Genes determine our characteristics. For example, our genes determine our height, eye color, blood type etc
Image Courtesy: National Institute of General Medical Sciences

4. Genes Code for Proteins
Genes are made of a molecule called DNA.
DNA contains instructions
to make proteins.
A protein
is named after
the gene which codes for it.
Image Courtesy: National Library of Medicine

5. DNA Structure DNA is a double-helical molecule.G C
DNA is a double-helical molecule.
It holds instructions to make proteins.
These instructions are stored as a code or sequence which is made up of four chemical bases:

6. Copying of DNA Cells in the body divide and grow.
When a cell divides, it has to first copy its DNA carefully so that each new cell gets a copy of the DNA without any mistakes.
Special genes called Mismatch Repair (MMR) genes control this process.
They make DNA repair proteins.
DNA repair proteins act like a spell checker and fix mistakes in the new DNA.
Image Courtesy: National Institute of
General Medical Sciences

7. Mutations in DNA Mismatch Repair (MMR) Genes
Mutations: Changes in the DNA that do not allow a gene to work properly.
When a DNA repair gene
is mutated, it results in the
loss of a DNA repair protein in the body.
Mistakes in the DNA
are not corrected and the new cells’ errors can cause them to divide uncontrollably,
thus resulting in cancer.
Image Courtesy: Genetic Science Learning Center-University of Utah

8. Lynch Syndrome increases cancer risk in these organs
Colon and Rectum
Endometrium (Uterus lining)
Ovaries
Stomach
Pancreas
Upper urinary tract
Biliary tract
Small intestine
Brain
Skin (Sebaceous carcinoma)
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9. Increased Risk of Multiple Cancers in Lynch Syndrome
Lynch Syndrome increases a person’s risk of getting some cancers when compared to the general population.
Early detection can be life-saving!!!
Note the Increased Risk of Multiple Cancers
In Lynch Syndrome

10. Inheritance of Lynch Syndrome
Lynch Syndrome is inherited such that one copy of the mutated gene is sufficient to cause cancer in the new generation.
If a person has Lynch Syndrome, he or she will have a 1 in 2 chance to pass this condition onto each child.
Lynch Syndrome can be inherited equally by men and women.
Image Courtesy: Genetic Science Learning Center-University of Utah

11. Potential Red Flags in a Family History for Lynch Syndrome
Multiple close relatives on the same side of the family with Lynch Syndrome-associated cancers1.
Individuals with more than one primary Lynch Syndrome-associated cancer
A family member with a Lynch Syndrome-associated cancer diagnosed before age 50
1. Lynch Syndrome-associated cancer: Colorectal, endometrial, stomach, ovarian, upper urinary tract, biliary tract, small intestinal cancers

12. Testing for Lynch Syndrome
Microsatellites are short DNA sequence repeats.
Everyone has microsatellites.
When there is damage to the DNA repair genes, these microsatellites become unstable and change size. This is called
Micro Satellite Instability (MSI).
This is why doctors test for MSI to see if a tumor is associated with Lynch Syndrome.

13. Lynch Syndrome Screening Strategy
Tumor
Testing for
Microsatellite Instability
Abnormal
Genetic testing for mutations
Normal
Probably not Lynch Syndrome.
You need family history evaluation

14. Catch Colon Cancer Early!
Important!
Colonoscopy helps detect colon cancer early in Lynch Syndrome patients.
Doctors may advise Colonoscopy
every 1-2 years, starting by age
20-25 years.
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15. Genetic Counseling
Genetic Counselors are trained professionals who can look at your personal and family history and evaluate your cancer risk.
Based on your risk, they may recommend the apt screening measures for you and your family members.
They help you learn about your disease, and provide emotional support.
Image Courtesy: Genetic Science Learning Center-University of Utah