7. Future of genomic medicine Flashcards
What is Monogenic disease caused by?
Single gene mutation
or Many mutations in 1 gene
Penetration not affected by environment
What is Polygenic disease caused by?
Many mutations in many genes
Environment has strong effect
Principles of DNA test
DNA isolation from sample
PCR (amplification of selected DNA region + digestion, if needed)
Visualisation on an agarose gel
Cystic fibrosis
Monogenic autosomal recessive disorder
Caused by CFTR mutations
What is the consequence of a CFTR mutation?
Affect chloride ion channels, leading to excessive mucous production in airways and pancreas
Effects breathing and secretion of pancreatic enzymes
What is the most common mutation in cystic fibrosis?
Delta F508
Deletion of 3 nucleotides at position 507-508 on CFTR gene
How can we test for delta F508 mutations?
Design primers either side of the delta F508 site for PCR
Normal length of DNA produced will be 63 bp
Because of the deletion, any chromosomes with delta F508 will be 3 bp shorter (60bp)
How can several single nucleotide changes can causing CF be identified?
With PCR
Restriction Fragment Length Polymorphism(RFLP) digestion
Restriction endonucleases recognize specific short DNA sequences
What can we use if the mutation is unknown to us?
Sanger sequencing
Whole genome next generation sequencing
Using NGS to sequence the entire genome
Very expensive
Targeted capture next generation sequencing
Using NGS on a single region/gene
Cheaper
Sensible for mutations in a known region
Exome is just 1% of whole genome but contains 85% of disease causing mutations
Genome panels
Contain gene regions associated with a disease/ phenotype
Focus on genes most likely to be involved
Minimises data analysis
Epigenome
Identify methylation of DNA which can explain the basis of monogenic disease
Transcriptome
convert mRNA to cDNA to sequence only transcribed proteins
Precision medicine
Use of genomics to tailor medical care to individuals based on their genetic makeup
What is the 100,000 genome project?
sequencing 50K cancer + 50K rare disease patients to identify causal genetic mutations
To improve diagnostics and therapeutics
Biomarkers
Identify presence/ severity of disease/ risk
e.g. miscarriage
How can NGS be used for rapid diagnostics in infectious diseases?
Sequence bacterial 16S rRNA - to identify bacterial species
Can sequence whole viral sequence
Nanopore technology
e.g. MinION
Very small sequencing machine
Used for small genomes e.g. viruses: Ebola
What are the 2 methods of gene therapeutics?
Direct delivery
Cell-based delivery
Describe direct delivery of gene therapeutics
Correct/ missing gene added to a viral vector
Directly injected into patient to incorportate into genome
Describe cell-based delivery of gene therapeutics
patients stem cells removed, cultured and gene introduced using retrovirus
Stem cells that incorporate gene are returned to patient
CAR T cells
Chimeric antigen receptors are added to patients T cells, modifies them so they recognise and bind to cancer cells
Leads to destruction of tumour cells
CAReceptors are specific to tumour antigens
Very effective in blood cancers
A living drug, can stay in the body for life
What dangerous side effect of CAR T cells could arise and how is this combatted?
Cytokine release syndrome (sCRS)
Combat with modification of T cells by CRISPR/Cas9
