The human genome and medicine Flashcards
List and explain the ways in which diseases can be prevented
> vaccinations: are pre-emptive strikes against infectious diseases. They prime the immune system to recognize pathogens. Some vaccines are almost completely effective- vaccines have eliminated smallpox and polio from most places in the world. Even a partially effective vaccine can be the difference between a pandemic(influenza, COVID) and a few localized outbreaks.
Understanding individual genetic predispositions to disease: for certain conditions, this can help to preserve health by suggesting changes in the individual’s lifestyle and/or medical treatment, eg. a risk factor that is detectable at the genetic level involves alpha1-antitrypsin, this is a protein that normally inhibits proteolysis by elastase in the alveoli of the lung. People that are homozygous for the Z mutation of alpha1-antitrypsin express a dysfunctional protein. This causes them to be at risk for emphysema because elastase causes damage to the lungs. They are also at risk for liver disease because of the accumulation of alpha1-antitrypsin in hepatocytes. Smoking makes the development of emphysema almost certain and if they are homozygous for the Z mutation they usually die from respiratory disease by 50 years old. The disease is caused by a combination of genetic and environmental factors.
In other cases, the detection of genetic abnormalities will not prevent a disease but can dispel the fear of the unknown, eg. Huntington’s disease. Genetic counseling is a preventative approach to avoiding abnormalities that arise from the dangerous combinations of parental genes.
How does the period of time when the disease is detected affect the treatment
The early detection of many cancers allows for simpler and more successful therapy. There are many different therapeutic strategies that are usually available, so if there is precise classification it allows better prediction of the course of a disease and optimal treatment, eg. oncologists classify leukaemias into 7 subtypes and if the subtype can be determined from gene expression patterns it allows for better prognosis and treatment
Explain why genetic counselling is necessary
Genetic counselling requires the consultation with a trained professional, who can arrange for appropriate diagnostic tests, explain the results and discuss the choices available. For eg, PKU testing of neonates is done by measuring the [ ] of phenylalanine in the blood. Most PKU is due to a mutation in the phenylalanine hydroxylase gene. However, a related condition, hyperphenylalaninaemia can arise from a defect in the metabolism of a cofactor of PAH called tetrahydrobiopterin by dihydropteridine reductase. DNA sequencing could detect a mutant PAH, but not a low expression level of dihydropteridine reductase. Gene sequencing is used for genetic counselling prospective parents who might be carriers of a mutant PAH gene and for prenatal testing.
Explain how recent scientific advances have accelerated the drug development process
> identifying metabolic features that are unique to a pathogen helps to identify targets for antibacterial and antiviral agents
knowing the structure of of a target (eg. protein) permits computer-assisted drug design by molecular modelling
there is a possible short cut to drug design that goes directly from gene sequence to inhibition of expression. without investigating the protein expressed- it uses short RNAs that bind to the messenger to inhibit translation, eg. there are some clinical trails that use RNA-based drugs like one that has shown to protect Rhesus monkeys against the Ebola virus. The problem is that the viral RNA genome mutates rapidly so it is likely that it will become resistant to the drugs.
Explain pharmacogenomics
Many drugs vary in their effectiveness in different patients- effective for some and useless for others. Some might handle treatment easily others might have serious side effects like discomfort through disability to death. Analyzing a patient’s genes and proteins can permit a selection of drugs and dosages that are optimal for individual patients- called pharmacogenomics. This eliminates the need for doctors to experiment with different therapies- which can be dangerous in terms of side effects, it is also wasteful and expensive.
