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Understanding Hereditary Cancers. Brittany Burnett, MS, CGC Certified Genetic Counselor John Muir/Mt. Diablo Health System Cancer Centers. Genes in the News. Factors Affecting Whether Any Person Gets Cancer. Carcinogens. Modifier genes. Response to DNA damage. - PowerPoint PPT Presentation
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Understanding Hereditary Cancers
Brittany Burnett, MS, CGCCertified Genetic CounselorJohn Muir/Mt. Diablo Health SystemCancer Centers
Genes in the News
Factors Affecting Whether Factors Affecting Whether AnyAny Person Gets CancerPerson Gets Cancer
Hormonal/ Hormonal/ reproductive reproductive
factorsfactors
Modifier genesModifier genesCarcinogensCarcinogens
Response to DNA Response to DNA damagedamage
Many Mutations Lead to Cancer
Malignant Cells
NormalCell
FirstMutation
SecondMutation
ThirdMutation
Fourth orLater
Mutation
Acquired Mutations
Altered Bone Cells
Normal Bone Cell
Normal Bone Cells
Mutation Occurs
Altered Gene
Hereditary Mutations
Fertilized Egg
Mutation Occurs
BrainPancreasBoneReproductive
Body Cells of Offspring
Mutation
SpermEgg
Many Mutations Lead to Cancer
Malignant Cells
NormalCell
FirstMutation
SecondMutation
ThirdMutation
Fourth orLater
Mutation
Different Genes – Different Functions
Pancreas CellBone Cell Brain Cell
Most Cancer Is NOT Inherited
Known Inherited Factor
All Breast Cancer Patients
Unknown Factor(s)
Searching Disease Families
Cancergene
Disease Present
Disease Absent
Cancer genemarkers
Disease-Linked Genes
Cancer gene markers Cancer gene
DNA
DNA molecule (chromosome)
Cell
Nucleus
Gene
Chromosomes
DNA Molecules
Cell ChromosomesNucleus
How many genes are we talkin’?
Chromosome X
Chemical Bases in DNA
DNA molecule (chromosome)
Chemical bases
Gene
AT
CG
DNA->RNA->Protein
Nucleus
DNA bases mRNA
DNA
Protein
Ribosome
Cell membrane
Gene
Chain of amino acids
Altered DNA->Altered Protein
NucleusDNA
Protein
Chain of amino acids
Ribosome
Gene
DNA bases mRNA
Cell membrane
Gene Mutations
Mismatch
Duplication Deletion
Frameshift Deletion
Gene Tests – Three Common Methods
Chromosome
Mutation Absent Mutation Present
Protein
DNA
Microarray Analysis
RNA prep
1.5 x 103 cellscDNA microarrays
High-throughput gene expression analysis
cDNA libraries
TotalRNA cDNA
(10–50 ng) oligo(dT)
EST sequencing
Technical Concerns
Searching Disease Families
Cancergene
Disease Present
Disease Absent
Cancer genemarkers
Genetic Tests Find Mutations, NOT DiseaseChances of Developing Breast Cancer by Age 65
Normal BRCA1Altered BRCA1
0
10
20
30
40
50
60
70
80
90
100
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10
20
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What are some of the cancer What are some of the cancer syndromes?syndromes?
Breast cancer genes: BRCA1, BRCA2, Breast cancer genes: BRCA1, BRCA2, p53, PTENp53, PTEN
Colon cancer genes: MLH1, MSH2, Colon cancer genes: MLH1, MSH2, MSH6, PMS2, APCMSH6, PMS2, APC
Melanoma genes: p16, othersMelanoma genes: p16, others
Renal/kidney cancer genes: pVHL, othersRenal/kidney cancer genes: pVHL, others
Prostate cancer genes: MSR1, ??Prostate cancer genes: MSR1, ??
What’s my risk for cancer?
The Genetic Counseling ProcessThe Genetic Counseling Process
Need to determine if testing is Need to determine if testing is reasonablereasonable
Evaluate for all cancer syndromesEvaluate for all cancer syndromes
Keep up with changing information on Keep up with changing information on diagnosis and testing methodsdiagnosis and testing methods
Psychological and social impact on Psychological and social impact on the patient and his/her familythe patient and his/her family
Long-term follow-upLong-term follow-up
Importance of Family HistoryImportance of Family History
The Questions We Ask…The Questions We Ask…Age and cause of deathPhysical findingsEnvironmental exposuresAnyone with previous Anyone with previous testing?testing?Origin of cancer(s)Origin of cancer(s)Age of onsetAge of onsetUnilateral/bilateralUnilateral/bilateral2nd Primaries2nd PrimariesCurrent cancer Current cancer surveillancesurveillanceEthnic backgroundEthnic background
Dominant Pedigree
= Affected
Benefits of Gene Testing
• Relief• Fewer Checkups• Informed Decisions• Intervention
Limitations of Gene Testing
Mutation Present But:
• May Never Lead to Disease• May Go Undetected
Major Limitations of Gene Testing
What Happens If We Find a What Happens If We Find a Mutation?Mutation?
PositivePositive genetic test result genetic test result
Possible testing for Possible testing for other adult relativesother adult relatives
IncreasedIncreasedsurveillancesurveillance
ProphylacticProphylacticsurgerysurgery
Lifestyle Lifestyle changeschanges
Chemo-Chemo-preventionprevention
Psychological Consequences
Who Should Know?
Confidentiality Concerns
Personal Decision
Difficult Decision
100
50
40
30
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10
0Want
To KnowDon’t WantTo Know
Percent ofPopulation
Importance of Genetic Counselors
Thank you for listening!Thank you for listening!
If you would like more information about cancer geneticsfor yourself, a friend or family member,
Call (925) 674-2581 and we’ll be happy to speak with you.Or just ask your doctor if it’s right for you.
Thanks again,Brittany Burnett, MS, CGC
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