Genetic Testing
Make a list of all the
genetic tests babies
get (you will
probably have had
these!)
Genetic screening
All babies in the UK are screened for the
following:
• Hypothyroidism
• Cystic fibrosis
• Phenylketonuria (PKU)
• Medium-chain acyl-coenzyme A
dehydrogenase deficiency (MCADD)
• Sickle-cell disease (only in families at risk)
Genetic Screening
• Lesson Learning Outcomes:
Describe the
process of
PGD
Suggest
what PGD
might be
used for.
Increasing Difficulty
Consider the
ethical
implications
of genetic
screening.
IVF
• What do you know about IVF?
Genetic Screening
• Video 1
• Video 2
• Watch these video clips
• What might we use PGD
for?
Sorting Time
• Put the cards into the correct order.
• In your books turn this into a cartoon that
shows how PGD is carried out
Uses of PGD
• Spider diagram what it might be used for and
what some of the consequences of its use
might be!
Uses of PGD
Video Time!
• Video 3
• When you are watching this video make notes
on:
– What is it?
– Why you might get it done?
– What are the risks?
– What are the potential ethical outcomes?
Rainbow Groups
• PICK A COLOUR
• Find out some information about genetic
screening
Share Time
• Share the
information you
have found out
Work in Pairs
• Answer the following question:
• Do you agree or disagree with the genetic
testing of newborn babies and the setting up
of a DNA database? Explain your reasons.
Drugs and Genetic
Screening
• In 2009 Carolyn Major started to take the medicine she hope would
cure her cancer. Instead, four days later; she was in an intensive
care ward with her heart struggling to keep going. She is one of a
small group of people whose bodies react very badly to the anti
cancer drug. Carolyn was lucky, She recovered with no permanent
damage done to her heart and so far the cancer hasn’t returned
either.
• In the future the genetic testing of adults may make problems like
this a thing of the past. Doctors think they can use genetic tests to
match medicines to some patients. Some people produce enzymes
that break down drugs very quickly, so they need higher doses of a
medicine than most other people. Other people don’t produce
enzymes to break down certain drugs in their body so they can be
poisoned by medicine that is meant to help them. In the future,
genetic testing may show if people have the genes for these
enzymes so we can all be given the drugs that work best for our
bodies’ genotype
Screening a Foetus
• If a couple know they are at risk of having a child with a genetic
disorder such as cystic fibrosis they can have tests to see if their
child has the disease. During pregnancy cells from the developing
foetus can be collected and the genes examined. This can be done
in two ways:
– Amniocentesis Test – where a needle is used to withdraw some
amniotic fluid from the mothers uterus. This fluid contains foetal cells.
This test is carried out at 15 – 18 weeks. There is a 1% miscarriage risk
and a very small risk of infection
– Chronic Villus Test – where a suction tube is inserted into the uterus
through the cervix. It is used to remove cells from the placenta. This
test is carried out at 10 -12 weeks. There is a 2% chance of
miscarriage and almost no risk of infection.
• The results from both of these tests are not 100% reliable.
• If the foetus has inherited two recessive alleles for a recessive
genetic disorder or one dominant allele for a dominant disorder the
child will have the disease. The parents may choose to end the
pregnancy. This is done with a medical operation (a termination or
abort)
Genetic Screening
• Testing the whole population for a genetic disorder is called genetic
screening. This is now done in the UK with some genetic disorders such as
cystic fibrosis, this allows the NHS to start treatment for these genetic
disorders early. This means that they extend the lives of people suffering
from genetic disorders.
• The decision about whether or not to carry out genetic screening is taken
by governments and local NHS trusts. People in the NHS have to think
about different things when they decide if genetic screening should be
used including: the costs of testing everyone, the benefits of testing
everyone, could the money be better spent on other things and benefit
more people.
• CASE STUDY: Four of Rabbi Joseph Ekstien’s children died from a severe
genetic disease called Tay-Sachs disease. In the general population one
baby in every 300 000 has Tay-Sachs disease but in the 1980s one baby in
every 3600 born to European Jewish families was affected and died. In
1983 Rabbi Ekstein set up a genetic screening programme. Couples
planning to marry were genetically tested. If they both carried the
recessive allele they were advised either to not marry or to have prenatal
screening and terminate effected pregnancies. As a result of this genetic
screening Tay-Sachs has almost disappeared from Jewish communities.
Who should know the
results?
•
•
•
Insurance companies assess what a persons risk is of dying earlier than average.
If they believe the risk is too high they may choose to charge higher premiums
than average. Some people think that insurance companies might use the
results of genetic tests in the wrong way. Individual people might do the same.
But having a gene that means you have a higher risk does not mean that you will
definitely die earlier. People are concerned that insurance companies might start
charging higher premiums, they may say that everyone must have genetic tests
or they might feel they have to keep the results of their genetic tests secret.
Scientists already use information about people’s DNA to help them solve
crimes. They produce DNA profiles from cells left at a crime scene. There is
usually only 1 in a 50 million chance of two people having the same DNA profile
(excluding identical twins)
Some people think there should be a national DNA database recording everyone
living in the country. If all the babies were to have their genome sequenced at
birth, this will easily be available in the future. Human right’s campaigners are
against a database for everyone’s DNA. They think it is an invasion of privacy
and puts innocent people on the same level as criminals