Transcript Lynch Syndrome

Lynch Syndrome
or
Hereditary Non-Polyposis Colorectal
Cancer (HNPCC)
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.
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
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
DNA Structure
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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:
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
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 CenterUniversity of Utah http://learn.genetics.utah.edu
Lynch Syndrome increases cancer risk in these organs
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Colon and Rectum
Endometrium (Uterus lining)
Ovaries
Stomach
Pancreas
Upper urinary tract
Biliary tract
Small intestine
Brain
Skin (Sebaceous carcinoma)
Image Courtesy:
http://www.cdc.gov/cancer/colorectal/pdf/
Basic_FS_Eng_Color.pdf
Increased Risk of Multiple Cancers in Lynch Syndrome
80.0%
Lynch Syndrome
increases a person’s
risk of getting some
cancers when
compared to the
general population.
Early detection can be
life-saving!!!
Cancer Risk for
General
Population
70.0%
Cancer Risk for
Lynch
Syndrome
patients
60.0%
50.0%
40.0%
30.0%
20.0%
10.0%
0.0%
Note the Increased Risk of Multiple Cancers
In Lynch Syndrome
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
http://learn.genetics.utah.edu
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 Syndromeassociated 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
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.
Lynch Syndrome Screening Strategy
Tumor
Testing for
Microsatellite Instability
Abnormal
Normal
Genetic testing
for mutations
Probably not Lynch Syndrome.
You need family history evaluation
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.
Image Courtesy:
http://learn.genetics.utah.edu
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
http://learn.genetics.utah.edu