*Your ConquerHSC Notes are consistently being revised throughout the 2019 Year to ensure quality!
Week 16 Content
Inquiry question: How can non-infectious diseases be prevented?
Learning Objective #1 – Use secondary sources to evaluate the effectiveness of current disease-prevention methods and develop strategies for the prevention of a non-infectious disease, including but not limited to:
- Educational programs and campaigns
- Genetic engineering
Week 16 Homework Questions
Week 16 Curveball Questions
Week 16 Extension Questions
Solutions to Week 16 Questions
Use secondary sources to evaluate the effectiveness of current disease-prevention methods and develop strategies for the prevention of a non-infectious disease, including but not limited to:
Educational programs and campaigns
So in this learning objective, we are required to assess the benefits and limitations of educational programs & campaigns as well as genetic engineering in preventing the incidence of non-infectious diseases.
Let’s first explore genetic engineering.
Gene therapy is within the field of genetic engineering whereby the DNA of the affected individual is modified to treat the underlying cause of the disease rather than the symptoms.
If the mutated gene causing the disease can be identified, gene therapy can be used to prevent the disease before the symptoms develop.
Thus, gene therapy can be used to both treat and prevent disease.
The use of genetic engineering (such as gene therapy techniques) to prevent non-infectious disease is still developing. In the past and today, there is a combination of success and failures.
This means that in order for gene therapy to be effective, more research and trials are required to be conducted to fully understand the interaction between the modified DNA and the disease.
Let’s now have a look at some case studies that you can use in the HSC Biology exam to tackle this learning objective.
Gene Therapy Case Study: Luxturna
Inherited disease caused by the mutation gene can result in the cell producing abnormal protein or prevent the production of protein as we have explored in prior modules.
Leber congenital amaurosis (LCA) is a rare, inherited eye disorder that result in the affected individual to have extreme difficulty seeing colours and, rather, only the outlines of objects. In other cases, it could result in completely blindless.
In gene therapy used to treat mutation in the LCA gene, it involves delivering a functional gene that specifies or codes for the normal protein the retina cell. This could allow the correction of the disease through the production of the necessary protein.
The gene is delivered using viral vectors (i.e. viruses).
Adeno-Associated Virus (AAV) is used to treat Leber congenital amaurosis as they only initiate a weak immune response and does not appear to cause disease in humans.
The genes specifying for the normal protein is inserted into the virus and a promoter region that is able to signal DNA replication of the gene when it’s located inside the cell.
Luxturna is the gene therapy method that successfully is able to deliver the functional gene to produce the normal protein to restore normal sight or vision.
Luxturna has been approved in late 2017 by the FDA as the first gene therapy for inherited disease.
Cost: $425,000 per eye.
Success Rate: In the clinical trial result that led to the FDA approval of Luxturna, there was a 93% success rate or 27 out of the 29 affected individuals. One year after the treatment, 21 of the 29 patients maintained normal vision of being able to navigate in low light environments.
Gene Therapy Case Study: Kymriah
This gene therapy, termed Kymriah, is suitable for treating B-cell acute lymphoblastic leukemia (ALL). The process involves extracting the affected individual’s T-cells. These cells are then genetically modified such that it contains a gene specifying for a chimeric antigen receptor (CAR).
This receptor is unique to the antigens that are present in the leukemia cells that cause the acute lymphoblastic leukemia disease.
The purpose of the CAR receptor is target and bind antigens on cancerous leukemia cells. This will activate the Helper T cells which secrete cytokines (and all the other mechanisms that discussed in Module 7). The result is the elimination of the cancerous leukemia cells.
Cost: The current cost for treating gene therapy is $475,000 for a single treatment. This does not include additional cost involved in the treatment such as hospitalisation fees, conditioning chemotherapy, treatment of side-effects such as cytokine release syndrome (CRS).
Therefore, the cost can exceed $1 million. This limits the accessibility of Kymriah to many patients.
Cytokine release syndrome can result in a range of conditions such as seizues, liver failure, fever, low oxygen levels, low blood pressure, etc. CRS can result in death.
Success Rate: Within 3 months of treatment, 83% of the 63 patients were removed from signals of cancer.
After 6 months, 11% of the treated individuals died and 89% of the affected individual who received treatment were survived. After a year post-treatment, 79% of the treated individuals survived.
Therefore, there is no guaranteed treatment.
Education Programs and Campaigns: Quit For New Life Program
There are screen programs advertised and offered by the government that are free of charge between a certain age to allow early detection of potential disease such as Breast Cancer and Bowel Cancer. By detecting signs of disease early, it would lower the risk of contracting the disease or easier cure.
Quit for new life program is run by the NSW Government to help pregnant Aboriginal women to quit smoking. Within this program, a training is provided to local health districts. This allows them provide advice and strategies to smoking, pregnant women.
There are also smoking cessation workers that provide follow-up support to pregnant women whom wish to stop smoking.
The program also offers a voucher system in providing up to 12 weeks of free nicotine replacement therapy (NRT).
- New employees in some local health districts provided feedback that there is minimal training provided by their managers in assessing whether pregnant women is qualified for the NRT provision
- Lack of smoking cessation workers in rural areas, most of them are working in urban areas.
- Data collection techniques are not appropriate to gather the relevant information to allowing the assessment of the real number of quitters during the collection period. For instance, if a smoker smoked at the start of the recording period (e.g. say first 2 months in a 1 year recording period) but then did not smoke for the rest of the period (e.g. final 10 months in the year), she would still be labelled as a ‘smoking’, but in reality, she is no longer a smoker. This has the effect of underreporting the real percentage of women who quit smoking during the data collection period.
- There is no data collected pertaining to the reduction or increase in smoking which would otherwise be useful in evaluating the effectiveness of the program.
- Overall, the program was anticipated to yield an effect on about 60% of all pregnant Aboriginal and Strait Islander residing in NSW. Due to lack of cessation workers and support from local district managers with training as well as poor data collection techniques, the effectiveness of the program is much lower compared to expectation.
Education Program: Needle and Syringe Program
With the timely implementation of the needle and syringe program, it has maintained the drug user population infected with HIV virus in Australia at around 1%.
- NOTE: This 1% is not including the population that does not take drugs to contract the HIV virus.
Comparatively, countries with such programs have over 50% infection rate in the national population.
The program prevent drug users from contracting AIDS after they stop injecting drugs.
It offers equipment required for injection so prevent using other people’s needles or syringe. It also provides education on drug abuse and information for treatment.
Although the program itself does not hinder people from injecting drugs, it has successfully maintained a low prevalence rate of the AIDS at around 1%.
As from the NSW Health Government website on the effectiveness of the program:
- “The program has prevented an estimated amount of 25,000 cases of HIV and 21,000 cases of hepatitis C.”
- “The savings to the health system in avoided treatment costs over a lifetime are estimated to be between $2.4 and $7.7 billion.”
- “The savings to the healthcare system in avoided treatment costs for HIV alone is more than 20 times the cost of running Needle and Syringe Programs.”
- “Needle and Syringe Programs have saved thousands of lives.”
Education Programs & Campaign: Slip, Slop, Slap! on Skin Cancer
We have already talked about how overexposure to the sun can cause skin cancer such as melanoma in Module 6. Specifically, we talked about how excessive exposure to ultraviolet radiation results in abnormal amounts of thymine dimers formed in oncogenes, tumour suppressor genes and/or stability genes which are not all be repaired.
There are many educational campaigns that are announced and run by non-profit-organisations such as the SunSmart program that is funded by Cancer Council Victoria and VicHealth. It educates public about:
- How they can prevent skin cancer (e.g. Slip, Slop, Slap, Seek, Slide) & recommended products
- How to individuals can detect early signs of skin cancer
- Recommended treatments for skin cancer
Effectiveness: The slip, slop, slap campaigns on educating the public to prevent skin cancer is effective and it has yielded positive results in decreasing the incidence rate skin cancer (e.g. melanoma) over the long term.
- “A long-term study of teenagers and young adults has revealed the cases of melanoma in young people fell 5 per cent each year from the mid-1990s to 2010.“ – Source: Melanoma Research Victoria
- “The rate of melanoma cases has fallen from 25 per 100,000 in 1996 to 14 per 100,000 in 2010 among people aged 20 to 24.“ – Source: Melanoma Research Victoria.
- The effectiveness of the campaign has been extended to a global whereby “Slip, Slop, Slap!” are recognised by people in many other countries that are not limited to Australia and New Zealand.