I/GCSE Biology - Genetic testing

In I/GCSE Biology, you should understand what genetic testing is after knowing the genetic diseases. Let's get started! 😆

In I/GCSE Biology, make sure to memorize the following points!

• It is now possible to test adults, children and embryos for a faulty allele if there is family history of a genetic disorder.
• If the test turns out positive, the individual will have to decide whether or not to have children and risk passing on the disorder.
• This is called PREDICTIVE TESTING FOR GENETIC DISEASES.

• Genetic testing can also be carried out to determine whether an adult or child can be prescribed a particular drug without suffering from serious side effects.
• TESTING AN INDIVIDUAL BEFORE PRESCRIBING DRUGS.

1. E.g. certain people are highly prone to getting liver damage while taking COX-2 inhibitor drugs.
2. A genetic test would ensure that only those patients who do have the prone gene are prescribed the drug.

• Embryos can be tested for embryo selection.
• The healthy embryos that do not have the faulty allele are then implanted.
• This process is called in vitro fertilisation (IVF).

• The process for embryo selection is called PRE-IMPLANTATION GENETIC DIAGNOSIS (PGD).
• After fertilisation, the embryos are allowed to divide into eight cells before a single cell is removed from each one for testing.
• The selected cell is then tested to see if it carries the allele for a specific genetic disease.
• PGD has risks including inaccuracy in results-healthy embryo not being implanted and it may also decrease the chance of the embryo surviving once it has been implanted.

In I/GCSE Biology, the risk of genetic testing is commonly asked in the exam!

Let's look at the diagram below to have a quick revision!

However testing adults and foetuses for alleles that cause genetic disorders has implications that need to be considered, including:

• Risk of miscarriage as a result of cell sampling for the genetic test
• Using results that may not be accurate , including false positives and false negatives
• Whether or not to have children
• Whether or not a pregnancy should be terminated
• Whether other members of the family should be informed

Besides, you should study about the ethical issue in I/GCSE Biology too!

• For example: governments may have the ability to impose genetic tests on individuals by implementing genetic screening programmes, but should they be allowed to do so?
• There is the potential for genetic testing to be used to produce detailed genetic profiles.
• These could contain information on everything from ethnicity to whether they are prone to certain conditions (e.g. obesity) or diseases (e.g. cancer).

However how will the information be used?

• Employers could potentially refuse to employ someone who possessed certain alleles
• Insurers may not cover a person who had genes that made them more likely to suffer a heart attack.

And we're done with this topic! Well Done!

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Drafted by Alyssa (Biology)

References:

1. "Genetic Testing: Uses, Side Effects, Procedure, Results", https://www.verywellhealth.com/thmb/RN78ICseQvdZpXApzZLY46ZXYNI=/1500x844/smart/filters:no_upscale()/2860730_color-5babc8d9c9e77c002ccae708.png
2. "Drugs". Photo from the internet.
3. "In vitro Fertilisation (IVF)", https://vivaneo-ivf.com/fileadmin/user_upload/img/Infografiken/VivaNeo-IVF-eng-min.jpg
4. "SciELO - Brasil - Preimplantation genetic diagnosis for cystic fibrosis", https://minio.scielo.br/documentstore/2317-6385/Bcm9qZRTRNZYjL3zfwYwr7w/bbb0d94578fb43c80fcc402b60471c5d8d2964c4.jpg
5. "Risk of genetic testing". Photo from the internet.
6. "Genetic Testing of Kids: Ethical Issues", https://i.ytimg.com/vi/qNW2YkWmhTA/maxresdefault.jpg