E10 Genetics and pharmacy

Question 1

state some characteristics of the human genome

Answer 1

• diploid
• 46 chromosomes
• 25 000 protein coding genes
• mitochondria have their own small genome

Question 2

where are lots of risk factors for genetic diseases caused by mutations located?

Answer 2

introns

Question 3

state some examples of the types of genes that haven’t been correctly identified

Answer 3

• mRNAs with short open reading frames
• long non-coding RNAs
• microRNA genes

Question 4

what is a pharmacogenetic variant?

Answer 4

• a polymorphism linked to the efficacy or toxicity of a drug
• now being discovered very regularly due to large screenings
• can be dominant, recessive, X-linked or mitochondrial

Question 5

state an example of a mitochondrial mutation

Answer 5

• MTRNR1 (mitochondrial ribosomal gene)

Question 6

what are aminoglycosides and how can people be sensitive to them?

Answer 6

• antibiotic that act on the bacterial ribosomal RNA to prevent translation in bacteria
• some mutations in 12S ribosomal RNA gene (MTRNR1) make the human mitochondrial ribosome sensitive to aminoglycosides
• this means the antibiotics stop translation in human cells too

Question 7

how can deafness be caused by aminoglycosides?

Answer 7

• people with deafness in the maternal line and mutations in MTRNR1 have a high risk of deafness after taking aminoglycosides
• using alternative antibiotics should be considered

Question 8

what mutations can and can’t be passed onto next generation?

Answer 8

only germline mutations (in the prospective egg and sperm cells) can be passed on

Question 9

what kind of drugs are the most promising for cancer? how does cancer signalling pathways link to stem cells?

Answer 9

• kinase inhibitors
• tyrosine kinase inhibitors stop the signal from being conducted into the cell
• signalling pathways for growth that go wrong in cancer are the pathways that are unregulated in stem cells

Question 10

describe the Philadelphia chromosome abnormality

Answer 10

• results from a translocation in somatic cells
• making of a fusion gene in a blood stem cell creates a tyrosine kinase that causes leukaemia (part of chromosome 9 is translocated onto chromosome 22)
• dominant mutation is not present in germline so is not passed on

Question 11

how is the Philadelphia chromosome abnormality treated?

Answer 11

• with tyrosine kinase inhibitor: imatinib
• fusion protein can now be blocked with the tyrosine inhibitor
• imatinib is a chemotherapy drug

Question 12

describe how genetic tests are outrunning our understanding of their meaning

Answer 12

• we don’t scientifically understand all the complexities and polymorphisms that cause disease
• we don’t have the capacity to interpret these in a way that is understandable to pass on to the population
• adequate genetic counselling isn’t currently available to explain the results of private genetic tests

Question 13

what are genetic counsellors?

Answer 13

• healthcare professionals trained in how to help patients cope with genetic disease

Question 14

what is happening to the price of private genetic tests?

Answer 14

falling rapidly

Question 15

describe the regulation of private genetic tests

Answer 15

• regulation is improving
• fewer tests are now sold directly to the public
• government must restrict provision of genetic tests unless they are simultaneously offering advice