a. Draw a flowchart outlining the laboratory steps in the DNA profiling procedure.
b. The diagram below shows five DNA profiles. The first is of blood found at the scene of a break and enter crime scene, where the thief cut himself on a broken window. The other four profiles show the DNA profiles of four different men who were seen in the vicinity at the time. Which of the four men was at the scene of the crime?
a.
Suspect A
b. Suspect B
c. Suspect C
d. Suspect D
e. Both B and C
c.
There are five DNA profiles shown in the diagram at right.
Mother – is the mother of the child.
Child – is the child whose paternity is in question.
Man 1, 2 and 3 are the three men who have been accused of being the father of the child.
You would be correct in concluding:
A. Man 1 is the father of the child
B. Man 2 is the father of the child
C. Man 3 is the father of the child
D. None of the men is the likely father as none of them match the child’s DNA profile completely
E. It is impossible to tell which of the men is the father as the child also has genes from the mother.
d. A strand of DNA on a chromosome has the following sequence of nucleotides:
AGC TCA GCC AAT GCT
What will be the sequence of bases on the complementary strand of DNA?
TCG AGT CGG TTA CGA
The table below shows the amino acid codons from DNA.
TTT
Phenylalanine
TCT
Serine
TAT
Tyrosine
TGT
Cysteine
TTC
Phenylalanine
TCC
Serine
TAC
Tyrosine
TGC
Cysteine
TTA
Leucine
TCA
Serine
TAA
STOP
TGA
STOP
TTG
Leucine
TCG
Serine
TAG
STOP
TGG
Tryptophan
CTT
Leucine
CCT
Proline
CAT
Histidine
CGT
Arginine
CTC
Leucine
CCC
Proline
CAC
Histidine
CGC
Arginine
CTA
Leucine
CCA
Proline
CAA
Glutamine
CGA
Arginine
CTG
Leucine
CCG
Proline
CAG
Glutamine
CGG
Arginine
ATT
Isoleucine
ACT
Threonine
AAT
Aspartic Acid
AGT
Serine
ATC
Isoleucine
ACC
Threonine
AAC
Aspartic Acid
AGC
Serine
ATA
Isoleucine
ACA
Threonine
AAA
Lysine
AGA
Arginine
ATG
Methionine
ACG
Threonine
AAG
Lysine
AGG
Arginine
GTT
Valine
GCT
Alanine
GAT
Aspartic Acid
GGT
Glycine
GTC
Valine
GCC
Alanine
GAC
Aspartic Acid
GGC
Glycine
GTA
Valine
GCA
Alanine
GAA
Glutamic Acid
GGA
Glycine
GTG
Valine
GCG
Alanine
GAG
Glutamic Acid
GGG
Glycine
Using the information in the table what will be the sequence of amino acids for the following DNA strand?
ATA GCA TCT CAA GCT AAA
Isoleucine Alanine Serine Glutamine Alanine Lysine
If there were a mutation so that the second base was changed from a T to a G so that the strand now reads
AGA GCA TCT CAA GCT AAA
What effect would that have on the amino acids coded for?
The amino acid would change to from Isoleucine to Arginine and therefore create a mutation of
concern.
If there were a different mutation where the second base was dropped completely so the strand now reads
AAG CAT CTC AAG CTA AA
Lysine Histidine Leucine Lysine Leucine Impossible to determine
What effect would that have on the amino acids coded for?
This mutation would be of grave concern as all amino acids change and we would not be able to code the last 3, as you cannot code fully for a 5 amino base instead of 6.
b) How would the IVF procedure be carried out for you and your spouse? What are the advantages & disadvantages ? What is IVF and outline the process from start to finish for both males & females in detail. (Suggested length 1 page)
LH AND LUPRON
In Vitro Fertilisation, commonly referred to as IVF, is a form of assisted reproductive technology (ART). This assisted pregnancy is commonly used for couples who are looking for a way around fertility issues and cannot conceive a child unassisted. This technology increases the chance that pregnancy will occur by joining the egg and sperm together in a protected environment and leaving the embryo to grow for some days until it is time for it to be transplanted back in the female’s uterus.
The steps in this process include:
Step 1: Initial meeting with specialist – At this meeting, both male and female are advised to attend as their medical history and any previous investigations and treatments are reviewed and noted. Also included in this meeting is preliminary advice about treatment options and paths possible for the future ahead in the hope to conceive, ensuring that these options suit each individual couple and their situation.
Step 2: Pre-treatment consultation – In this scheduled meeting, your treatment plan will be reaffirmed and questions and queries are answered, relevant consent forms are signed. A double check of any possible treatment interferences are discussed.
Step 3: Treatment begins – Initial treatment with your fertility nurse begins, here you are given the medication needed and the treatment cycle is explained. You will also be supplied with Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) injections and the woman is shown how to give herself these injections. The women is also given another Lupron (Leuprolide Acetate) hormone for 10 – 12 days, which essentially shuts down the hormone reproductive system in the women’s body. Whilst the process of shutting it down happens, the development of follicles beings, FSH injections are adjusted to each patient’s response and continues until full maturity of follicles. Egg retrieval is scheduled for 32 hours later.
FSH and LH are an injection with a very fine needle just under the skin, the hormone injected is produced by the pituitary gland (located behind the eye), together they stimulate egg production. In the case of IVF, this injection is given with the aim to produce 10 – 15 eggs in the women’s ovaries, then fertilizing them outside of her body. The more eggs produced, the better as if the fertilisation is unsuccessful there are more eggs available, increasing the chance of a successful pregnancy.
Step 4: Treatment Monitoring – During this repeated step, an appropriate time for egg collection is determined through the use of regular blood tests and ultrasounds to measure the size and number of ovarian follicles, and also to check up on hormone levels.
Step 5: Trigger Injection – Once an optimum number and size of follicles is reached, trigger injections begin, using hCG (human chorionic gonatrophin). These injections replace Leteinising Hormone, naturally occurring in the body, triggering ovulation. The operation of egg collection will begin 36 – 38 hours after the trigger injections begin.
Step 6: Egg Collection day in surgery – Day surgery for egg collection takes place under light general anaesthetic or local anaesthetic with sedation and ultrasound guidance. This surgery requires the women to be at the hospital for 4 hours, and for the man to provide a fresh semen sample on the morning of the surgery, so the eggs are able to be immediately fertilised.
Step 7: Egg Fertilisation – The eggs removed in the egg collection surgery are then taken to a laboratory and prepared for fertilisation by being placed in a culture medium (a solid, liquid or semi-solid designed to support the growth of microorganisms or cell). The egg is then fertilised by being placed in a dish with prepared sperm.
Step 8: Embryo Development – To mimic the temperature of the environment for an egg in a female body, incubators at 37 degrees are used to hold the egg and sperm. The following day, eggs are examined by scientists to look at the development of the embryos and if fertilisation has occurred, the patient will be called in to discuss the results.
Step 9: Embryo transfer – Typically five days after egg collection, a simple day surgery takes place where the embryos are transferred into the uterus through a catheter, similar to the procedure of a pap smear.
Step 10: Embryo freezing – For future use, extra embryos not used during this treatment can be frozen.
Step 11: Pregnancy Test – Appointments are arranged for a blood test to take place, two weeks after the embryo transfer. Blood tests are used in this case as urinary pregnancy tests can produce an incorrect result due to hormone medications. If this test is positive, ultrasounds are booked for around three weeks after.
Advantages
Disadvantages
Women with a range of fertility issues such as;
– Blocked or damaged fallopian tubes
– PCOS
– Endometriosis
– Premature ovarian failure
– and even unexplained infertility
– older patients with low ovarian reserve
are granted the opportunity to conceive a child.
IVF may not be successful, success is not guaranteed. Patients often have to go through the process more than one time before the treatment is successful.
Males who suffer from infertility problems are also given the opportunity through intra-cytoplasmic sperm injection (ICSI). .
Like the majority of medical treatments, IVF comes with associated side effects and risks. Fortunately, a possible severe risk of Ovarian Hyper-stimulation syndrome (OHSS), is dramatically decreased or eliminated by the use of fewer drugs and mild IVF cycle.
Success rates are higher than other forms of assisted reproductive technology.
The risk of a multiple pregnancy also applies to IVF patients, which can lead to premature labour, miscarriage, stillbirth and infant health problems.
Single women and same-sex couples also benefit from the opportunities IVF provides.
Going through IVF has its effects on the patients both emotional and psychologically.
Ability to freeze unused embryos that can be donated to research or another couple, or even saved for possible future use.
IVF can be a financial issue for the patients, it can be quite costly.
The IVF cycle cost with IVF Australia sits at a cost of $9,290 just for the one cycle.
Potential ongoing costs such as ICSI, Embryo Freeze and Sperm Freeze come at an extra cost on top of the initial cycle cost.
c) What is PGD & why is it used? What are the advantages & disadvantages? (Suggested length 1/2 page)
Pre – implantation Genetic Diagnosis/ Testing (PGD/ PGT), is a technique performed in a scientific lab where embryos are tested for a specific genetic condition or chromosome abnormality.
The technique is used to assist and maximise the chances of the outcome being a healthy baby by only selecting the embryos that are chromosomally normal or those unaffected by a specific disorder for transfer during an IVF cycle.
This testing requires the woman to go through a standard IVF cycle, and whilst the embryos are being developed in the laboratory, about 5 cells are removed from each of her embryos on day 5/ 6 when the embryo carries about 100 cells, and tested in either of these ways:
– Chromosome Testing (Next Generation Sequencing) – this technique tests all 24 chromosomes of each embryo that the woman produces during IVF, giving the ability to only transfer the chromosomally healthy embryos.
– Karyomapping – this technique is used when either the man or woman knows they are carriers of a serious single gene disorder. Through Karyomapping, you are able to identify the embryos that are unaffected by the condition that either of the parents have, preventing it from carrying on to the next generation.
PGD with Chromosome Testing (Next Generation Sequencing), the cost incurred for this treatment is $700 per embryo biopsied.
PGD with Karyomapping, testing for single gene disorders costs $1,640 for the initial evaluation plus $700 per embryo biopsied.
Advantages
Disadvantages
The opportunity to be able to detect known genetic diseases or chromosomal abnormalities.
Risks of ovarian hyper stimulation syndrome.
Prevents unhealthy embryos from being transferred into the uterus.
Healthy baby is not guaranteed as some genetic diseases and disorders are not screened.
Multiple pregnancy risks are reduced dramatically by the identification of healthy embryos before being transferred.
Possible chance of receiving false negative results meaning abnormal embryo is transferred, and a possible miscarriage, and healthy embryos are discarded reducing chances of a healthy pregnancy.
Decreases the risk of the child being inheriting a serious disorder
Risk of potential harm to the embryo(s) such as biopsy or freezing.
Reduce possible medical and financial burden places on parents as they are given the choice to transfer an affected embryo and are able to make altered plans if so.
For testing to take place, there are significant medical costs that medical insurance most likely do not cover.
Ability to choose the gender of the child.
Some people believe it is unethical and it is seen as human genetic engineering
Less chance of having a miscarriage for couples who have PGD tested
Each screen only tests for one disease
Some couples have moral conflict with regards to PGD testing and disposal of affected embryos.
d) As a result of tests carried out previously on you and your spouse you are aware that you both carry the very rare recessive gene for 3-M dwarfism. The specialist carrying out the PGD on your embryos has asked if you would like them tested for 3-M syndrome with a view to not using an embryo if it was shown to be homozygous for 3-M dwarfism. Would you accept this offer from the Doctor? What is 3M Dwarfism? Explain your reasoning for testing or not and if you were told your embryo had 3M Dwarfism whether or not you would implant it – provide researched justification? Make sure that you discuss what the chances would be of you having a child with 3-M dwarfism – provide evidence. (Suggested length 1 page)
Dwarfism is a condition with the main characteristics being short in the arms and legs or trunk. Dwarfism refers to over 300 conditions that cause this abnormal skeletal growth, Achondroplasia is the most common out of all 300 conditions and occurs in one in 25,000 children, both male and female equally as common. Most children born as a dwarf have normal – sized parents, the experience normality in intellectual development but may experience delay in some development such as; motor skills and control of movements in the head. These short statured people grow to around 130cm for men and 125cm for women.
People affected with the condition of dwarfism are likely to have the following features: trunk of relatively normal length, short arms and legs in proportion to trunk, bowed legs, lessened joint mobility in elbow, ‘double jointed’ in other joints due to loose ligaments, short hands and feet, large head, flat face, teeth crowding due to small upper jaw, prominent forehead and a flattened bridge nose.
For about 80% of dwarfs, the genetic mutation that causes achondroplasia (when the parents are normal size) occurs during fertilisation of the mother’s egg. It is still unknown as to how or why the mutation occurs and how it forms to have the characteristics of achondroplasia. The remaining 20% of dwarfs inherit the abnormal gene from the parent who has the condition, if one of their parents are affected by the condition the child has 50% of inheriting the gene for achondroplasia.
Also amongst these 300 dwarf syndromes is 3M syndrome, an extremely rare variation with only 50 individuals around the world known to be affected. This syndrome falls in with the 300 other variations and has the same symptoms and is not life – threatening. This condition is inherited through an autosomal recessive pattern, meaning the parents of an affected child must carry the mutated gene but don’t show symptoms of 3M.
2 Normal parents producing a homozygous 3M child: