Lec 13 (medical genetics) Flashcards
Social, ethical and policy challenges involved with genetic testing
HART Act 2004
human assisted reproductive act
types of genetic tests available
preimplantation genetic diagnosis
Define medical genetics
The specialty of medicine that involves the diagnosis and management, and counselling of genetic disorder
They are the molecular changes that occur during the development of genetic disease
Life-threatening or provide a lot of pain)
Give examples of conditions in medical genetics
- birth defects
- metabolic disorders
- mitochondrial disorders
- cancer
Life-threatening or provide a lot of pain)
What types of genetic tests are used and why?
- carrier screening e.g a carrier for a cystic fibrosis
What types of genetic tests are used and why?
- carrier screening e.g a carrier for a cystic fibrosis
- then PGD can be used - Prenatal diagnostic testing e.g Down Syndrome
- Newborn screening
what is the genotype of cystic fibrosis
homozygous recessive
25% of offspring having cystic fib if parents are carriers (hetero)
What occurs if a couple have been screened for cystic fibrosis and 1 or both of them are carriers of the gene? What mechanisms can be used to ensure their offspring will have a reduced chance of getting cyst fib?
Carry out a preimplantation genetic diagnosis (PGD)
this method tests an embryo before implantation in the uterus for single-gene (mendelian) disorders
What occurs if a couple have been screened for cystic fibrosis and 1 or both of them are carriers of the gene? What mechanisms can be used to ensure their offspring will have a reduced chance of getting cyst fib?
Carry out a preimplantation genetic diagnosis (PGD)
this method tests an embryo before implantation in the uterus for single-gene (mendelian) disorders
describe the method of PGD
PGD = preimplantation genetic diagnosis
take the sperm and oocyte and fertilise it in vitro (in a petri dish). And then test the embryo for cystic fib.
If the embryo comes back as cystic fib. then the embryo is not used.
But if it comes as negative, then the embryo can be used and implanted into the female.
Describe Newborn screening
Once the baby is born, within 48 hours
the parent can give informed consent of the baby’s heal to be pricked- therefore, a bloodsample is collected on to a card called a Guthrie card.
DNA/protein can be extracted from the card. usually protein is extracted to perform mass spec to determine the absence of a specific protein.
64,000 babies born a year, how many of them are screened through the newborn screening test and are with a genetic disease?
45 are born with a genetic disease
Treatment can then be given to reduce the symptoms
How many babies have cystic fib in a year in NZ?
8 cystic fibrosis babies a year
describe predictive genetic testing
predicting adult-onset disorders the healthy (presymptomatic) adults
- estimating the risk of developing adult-onset disease
e. g Huntington’s Disease
no. of CA repeats on chromosome 4
Describe diagnostic genetic testing
- most common in NZ rn in terms of covid 19
- yes/no covid 19
conformational diagnosis of asymptomatic individual
What are the main types of genetic tests used
5
1) predictive genetic testing
2) diagnostic genetic testing
3) pharmacogenetic testing
4) research genetic testing
5) forensic/identity testing
Describe pharmacogenetic testing
- now available to guide treatments for certain cancers
- drug may work better depending on the mutation status
Describe research genetic testing
helps scientists learn more about gene function and develop gene-based treatments
- find mutations
- find the gene function to explain the cause of the particular symptoms
-results don’t directly help the participant, but may benefit their offspring
Describe forensic/identity testing
after death
genetic markers are used
ART stands for __
Assisted reproductive technologies
what is ART
methods that replace the source of a male or female gamete, aid fertilisation or provide a uterus
In the US, around 1% of the 4 million births each year are from ARTs
In aus, NZ >70kART cycles are undertaken each year, resulting in the birth of 1 in 25 children
rising to 1 in 12 women aged >35yr
ART was developed to treat
infertility but are becoming part of genetic screening
because worldwide, there is an increase in the level of infertility
How many individuals experience infertility in
up to 20% pf australian and NZ couples will experience infertility and undergo ART
government-funded ART treatment is available in NZ only for those who meet strict eligibility criteria
Give examples of ART
- replacing with a a gamete (sperm or egg)
1) intrauterine insemination IUI (5-15% success)
2) surrogate motherhood
3) In vitro fertilization (IVF)
4) gamete intrafallopian transfer (GIFT) (22%)
5) oocyte banking and donation (3%)
6) preimplantation diagnosis PGD (29%)
7) sequential polar body analysis
