Genetic Variation & Genetic Disease

Question 1

Single nucleotide polymorphisms (SNPs) occur approximately every

Answer 1

Single nucleotide polymorphisms (SNPs) occur approximately every 1,000 base pairs

Question 2

Pros of genetic variation

Answer 2

Genetic variation allows a population to survive to changing environmental conditions.
Advantageous traits can be passed on to next generation
disadvantageous traits are lost through generations, driving natural selection

Question 3

Cons of genetic variation

Answer 3

New genetic mutations = can cause disease

Some mutations can be deleterious but same time offer protection to other diseases (e.g. sickle cell traits protect from malaria, CF carriers are protected from cholera)

Question 4

Where are most genetic differences located in genome

Answer 4

SNPs (occur every 1,000 base pairs)

Question 5

Alleles with ____ penetrance are very rare

Answer 5

Alleles with HIGH penetrance are very rare

Question 6

Alleles with _____ penetrance are common

Answer 6

Alleles with LOW penetrance are common

Question 7

List 3 ways we detect genetic variation

Answer 7

• PCR (Polymerase Chain reaction)
• sequencing
• NGS (Next Generation Sequencing)

Question 8

What is a PCR used for

Answer 8

PCR is used to see what changes in DNA cause disease/ make individuals susceptible to a disease

Question 9

Describe the process of PCR simply

Question 10

Next Generation Sequencing (NGS) is better for genetic analysis than PCR, what are 3 things it can do

Answer 10

• WHOLE EXOME SEQUENCING (can sequence whole exomes= coding portions of genome)
• WHOLE GENOME SEQUENCING (sequence 100% of genome)
• WHOLE RNA sequencing (sequence expressed RNA)

Question 11

Define exome

Answer 11

EXOME is a sequence of exons in a genome

Question 12

Define exon

Answer 12

exons are protein coding portions of genome

Question 13

Define intron

Answer 13

Introns are stretches of DNA between exons that are non-coding

Question 14

What is known as the ‘gold standard’ of genetic testing

Answer 14

Sanger sequencing

Question 15

What does ddNTP stand for

Answer 15

ddNTP= dideoxyribonucleic acids

Question 16

What is meant by the term bioinformatic tool

Answer 16

Bioinformatics, as related to genetics and genomics, involves using computer technology to collect, store, analyze and disseminate biological data and information e.g. NGS DNA information

Question 17

Why do we use NGS

Answer 17

good for discovering new genes that cause disease especially rare inherited diseases

Question 18

Why is combining genetic diagnosis and targeted therapy beneficial to patient

Answer 18

If we can attain genetic info from placenta via genetic diagnosis—
It offers personalised approach to patient care, where treatment is tailored to specific genetic conditions of patient

Question 19

Describe what we know about gene therapy (+ example)

Question 20

Describe general chemotherapy

Question 21

Problems with general chemotherapy

Question 22

Role if topoisomerase

Answer 22

Topoisomerases help DNA unwind so that transcription can occur

Question 23

Give 3 examples of chemotherapeutic agents

Answer 23

Taxanes
Vinca alkaloids
Topoisomerase inhibitors

Question 24

Role of topoisomerase inhibitors in general chemotherapy

Answer 24

Topoisomerase inhibitors helps DNA stay wound up/ inhibits unwinding of DNA
Therefore stops transcription of cancer cells

Question 25

Explain why targeted therapy beneficial to cancer patients (e.g. trastuzumab + HER2 growth factor receptor)

Question 26

Role of pharmacogenomics in targeted therapy

Answer 26

Pharmacogenomics depends on who’s identifying specific mutations— allows us to identify genetic variation in specific metabolic pathways i.e. patients respond to drugs differently

We then can alter drugs to be metabolised more quickly (for patients who take long to absorb/metabolise)
We can give larger doses to patients who eliminate drug faster

Question 27

Ethical issues of genetic testing

Question 28

Why do we use Sanger sequencing

Answer 28

Sanger sequencing is a fast, cost effective way of reading the sequence of small targeted regions of the genome. It is widely used to test for known familial variants