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Week 4: Breast Mass > Germline and Somatic Mutations > Flashcards

Flashcards in Germline and Somatic Mutations Deck (16)
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Germline vs somatic mutation

Germline: inherited variation in germ cells (transmitted to offspring)
Somatic: acquired alteration of DNA sequence


What is the most common risk factor for cancer?



3 clues in a personal history that there is a hereditary cancer present

Early age of onset
Multiple primary cancers
Rare cancer types


4 clues in a family history that there is a hereditary cancer present

Same cancer in 2 or more relatives
Multiple generations affected
Same or related cancer types
Early age of onset of family members


What type of inheritance is usually associated with hereditary cancers

Autosomal dominance


3 conditions to be met for cancer genetic testing to be offered

Individual or family history suggestive of cancer susceptibility
Test can be adequately interpreted
Results will aid diagnosis or influence management of the patient/family members


BRCA1/2 genes are associated with what cancer syndrome?

Hereditary breast and ovarian cancer syndrome


Benefits of oncologist-led genetic testing

Improved efficiency (reduced wait times)
More effective working relationships with oncology team
Positive feedback from patients


4 reasons to get a hereditary cancer diagnosis

May alter treatment
May help patient decide on risk-reducing strategies to manage risk of future cancer
May help prevent or detect cancer early in a family member
Family members can be tested to determine cancer risk


3 ethical considerations of hereditary cancer testing

Psychological implications
Genetic discrimination
Disclosure of genetic results to relatives (duty to report vs confidentiality)


5 places to sequence the genome

Site specific
Single gene
Gene panel
Whole exome
Whole genome


Sanger sequencing

Based on selective incorporation of chain-terminating dideoxynucleotides
Used for smaller scale sequencing and validation of next gen sequencing


3 main steps of next generation sequencing

1. Library (break up entire genome)
2. Sequencing
3. Data analysis


3 pros and 1 con of single gene sequencing

Pros: targeted assessment, fewer variants of uncertain significance, accurate
Con: time consuming


3 pros and 1 con to using a multi gene panel

Pros: increases likelihood of detecting a mutation, unexpected diagnosis impacting management, time and cost efficient
Con: Increases numbers of VUS


2 pros and 2 cons to whole genome sequenceing

Pro: comprehensive assessment, can evaluate structural changes/copy number changes/mutational signatures
Cons: high number of VUS, expensive