Genetic Screening Flashcards
Define “genetic screening”
Checking DNA for alleles causing genetic disease
Give 3 types of genetic screening
- Identification of carriers
- Preimplantation Genetic Diagnosis [PGD]
- Prenatal Testing
Who are the identification of carriers treatment offered to?
Individuals with family history of a genetic disorder
What are the advantages of identification of carriers treatment? 2
- Healthcare professionals can advise people on risk of developing disease in later life
- Individuals can make informed decisions on whether to have children and future treatment
What is the identification of carriers?
Individuals are informed whether or not they carry a recessive allele for a genetic disease
What is preimplanation genetic diagnosis?
- Embryos produced by IVF are screened for genetic disorder alleles before implantation
What are the advantages of preimplantation genetic diagnosis? 2
- Reduces chances of giving birth to a baby with a genetic disorder
- Avoids abortion
What are the issues with the identification of carriers? 4
- Could cause emotional distress
- Possibility of false results
- Other genetic abnormalities could be found
- Genetic discrimination e.g from insurance companies
What are the issues with preimplantation genetic diagnosis? 2
- False results
- Designer babies - choosing appearance characteristics
What is prenatal testing?
Screening unborn babies for genetic disorders
Who is prenatal testing offered to?
Pregnant women with a family history of genetic disease
What are the two types of prenatal testing?
- Amniocentesis
- Chorionic Villus Sampling
How is amniocentesis carried out? 3
- Test sample of amniotic fluid
- Obtained via abdomen with fine needle
- Fetal DNA analysed
What is amniotic fluid?
The fluid surrounding the fetus
When can amniocentesis be carried out?
15-20 weeks of pregnancy
When can results of amniocentesis be obtained? 2
- Full results: 2-3 weeks after sample taken
- Rapid test [only for common disorders]: 3-4 days
What is the risk of miscarriage for amniocentesis?
1 percent
How is chorionic villus sampling carried out?
- Sample of chorionic villi in placental tissue obtained
- Fetal DNA analysed
What are the two ways the chorionic villi sample can be obtained?
- Fine needle in the abdomen
- Catheter in the vagina
When can chorionic villus sampling be carried out?
11-14 weeks of pregnancy
When are initial results available for chorionic villus sampling?
In a few days
What is the risk of miscarriage for chorionic villus sampling?
1-2 percent
What is the advantage of CVS over amnioscentisis?
Can be done earlier in pregnancy so an earlier decision about abortion can be made
What are the risks of using all prenatal testing?
- Emotional stress
- Miscarriage
- Genetic discrimination
- False results
What is the main advantage of amniocentesis over CVS
Less risk of miscarriage
