As you’ve learned your genetic make up is responsible for how you look and the possible diseases that could develop.
However there are Pros and Cons to running these genetic testing.
Pros
Your able to decide if you want to have kids.
You can plan for your future
We can test embryos for genetic diseases prior to them being fully developed.
Cons
Tests are not completely reliable. Current tests for HD detects 90% of cases.
When it is not detected it is called a False negative.
If it is detected but you don’t actually have the disease, it is called a false positive.
There are different types of genetic tests which can be conducted.
An Antenatal test is used to analyse and individual’s DNA before they are born.
We can use this test to detect down syndrome and other inherited disorders.
Once the baby is born we can use Neonatal testing to detect genetic disorders.
In the UK all babies are screened for phenylketonuria, congenital hypothyroidism and cystic fibrosis.
Pre-implantation genetic diagnosis (PGD) is used on embryos before implantation.
During IVF the egg cell is fertilised outside of the womb. Once the cells have reached the 8-cell stage one cell is removed and tested.
Cells are tested for the diseases causing alleles (Huntington’s).
If you’re carrying a recessive allele you are called a ‘carrier’. In order to see if you are carrying this allele a Carrier test is done.
Disorders such as Cystic Fibrosis, are recessive, so both parents should be checked if there is family history.
Predictive testing is used to detect genetic disorders where the symptoms develop later in life (Huntington’s). People who show no symptoms but have a family member with the genetic disorder may use this testing to make decisions about their future plans.
Questions
1. What are false negative and false positive results?
2. Why is it important for people to know about false results?
3. Explain what is meant by the term ‘genetic screening’
4. Give two arguments for and two against genetic screening for cystic fibrosis
5. Research the following genetic diseases. Find the symptoms and possible genetic tests which can be carried out to identify the disease
Huntington’s disease (HD)
Phenylketonuria
Cystic fibrosis (CF)
6. If you were diagnosed with HD, at your age. What are some changes you would make to your future plans? What are 2 positives and 2 negatives about knowing your genetic condition?
Who makes the decisions?
The decision to use genetic screening is controlled by the governments and local NHS trusts (Hospitals and Mental health service). When deciding to screen people for a genetic disease you have to consider
What the costs of testing everyone for a specific allele is?
What are the benefits of testing everyone?
Is this test an efficient use of resources?
Another thing to consider before testing for genetic disorders, are the ethical issues surrounding it.
Who should know the results?
What are the long term effects on the persons life?
