Presentation on theme: "Baby Doe v. The Prenatal Clinic"— Presentation transcript:
1Baby Doe v. The Prenatal Clinic Norris Armstrong University of Georgia-Athens
2Baby Doe v. The Prenatal Clinic John looked at the baby squirming in his arms. He and his wife, Jane, had been trying to have kids for a couple of years and had finally been successful. The pregnancy was uneventful and, though the delivery took longer they either of them would have liked, everyone seemed to be doing fine.This was a new experience for John. Everything about the child he was holding seemed so small and delicate. Even so, some things seemed unusual. For example, the baby looked a little cross-eyed, and its face seemed a little flat when he looked the baby from the side. Also, the baby’s hands and feet were even smaller than he would have expected, and the hands had a strong crease that ran across the middle of the palms. John realized he was probably imagining things. After all, though he had a younger brother, he was definitely no expert on newborn babies.
3One week later…But one week later John and Jane sat in the clinic’s conference room in stunned silence. “I had to run some tests to be certain,” said their doctor. “However, the results confirmed what I suspected. Your child has Down syndrome. I am afraid there is no cure. However, early intervention can improve the outcome you can expect. I can give you the names and numbers for several organizations that can give you more information and advice. There are other resources you can try as well………………”John and Jane did not hear much of what the doctor said after the diagnosis. The only thought that kept running through their minds was, “How could this have happened?”
4The CaseYou’ve been hired by a law firm to serve as an expert witness for John and Jane’s case. To help your client and to appropriately inform the court, you will need to explain what actually causes Down syndrome to the jury. You will also need to explain whether or not the clinic could have done anything that contributed to the baby’s condition.Since it was likely to have been many years since most of the jurors had studied biology, one of the things you probably have to do is give them a crash course on some basic biology. For starters, what exactly is Down syndrome?
5CQ#1: What is Down syndrome? A condition caused when the mother drinks alcohol while pregnant.A form of childhood cancer.A birth defect resulting in a split upper lip and speech problems.A condition caused when the baby has too many copies of a chromosome.A form of brain damage that results when the baby receives too little oxygen during birth.
6Down syndromeA chromosomal disorder resulting from a partial or complete extra copy of chromosome 21.Multiple developmental and health effects including:Short stature, distinct facial features.Mild to moderate physical and cognitive impairment.Increased risk of problems involving heart, respiratory, digestive, hearing, vision, and/or thyroid glands.Trisomy 21 (95% of all cases): three complete copies in all cells.Mosaicism (1-2% of cases): three copies in some but not all cells.Translocation (3-4% of cases): partial copy of chromosome 21 attached to another chromosome.
7What are chromosomes?An E. coli bacterium was attached to an EM supporting grid and then gently broken open. The DNA in its native form has spilled out including a small circular plasmid. Image courtesy of Jack Griffith, University of North Carolina. Used with permission.
8What are chromosomes?Human cell = >6 billion nucleotide base pairs (~2 meters)Wrapped around protein = chromatinDNA/protein = chromosomeE. Coli bacteria have approx 5 million base pairs. Human cells have approximately 1000X as much DNA.
9How many chromosomes do humans have? Humans are diploid (2n)Two of each chromosome, one from each parent.n = 23 unique chromosomes (haploid #)2(n) = 46 total chromosomesCurly hair alleleStrait hair alleleThe two copies of each chromosome in human cells are homologousDifferent versions - same genes in same locations but different DNA sequence.Different versions (alleles) of a gene may promote different traits (e.g. hair type).
10CQ#2: The diploid chromosome number in standard laboratory mice (genus Mus) is What is n for this organism?
11Getting Ready The first court date for John and Jane’s case is coming up and it is time to start organizing your testimony. You need to help the jury determine whether the doctors at the clinic may have done something to cause the baby to have the incorrect number of chromosomes. A good place to start might be to describe how cells get the right number of chromosomes in the first place.
12How do cells get the right number of chromosomes? DNAHow do cells get the right number of chromosomes?DNACell DivisionDuplicate cell componentsOrganellesCytoplasmChromosomesDNAHow does a cell do this?Won’t worry about organelles, focus on DNADNA2. Separate the material into two daughter cells
18Families: similar yet different. Why? Asexual ReproductionSingle parentOffspring identical to each other and parentSexual ReproductionTwo parentsOffspring are uniqueOffspring are similar to each other and parentsCombine DNA from two individualsCombines characteristics of both individuals
19Why do diploid organisms need to have specialized sex cells? Sex cells (gametes: sperm or egg) allow traits to be combined from two organisms2n (46)2n (46)+4n = 92too many
20+ Sexual Reproduction Gametes have only one of each chromosome Requires special cell division: MeiosisDiploid cells (2n) Gametes (n)Takes place in gonads (testis, ovary)n (23)n (23)+2n = 46
21How is Meiosis different from Mitosis? Cells divide 1xMeiosisCells divide 2x2n2n2n2nnnDiploid CellsnnnnHaploid Cells
23sister chromatids line up Mitosis MeiosisCell division is overCells divide again;sister chromatids line upDone
24How many unique gametes can a cell with two pairs of chromosomes make?
25(2)23 > 8 million different possible gametes Why bother?For humans with 23 pairs of chromosomes?(2) > 8 million different possible gametesFor a couplepossible unique offspring(8 million) x (8 million) = (64,000,000,000,000)But wait! There’s more!
26Crossing over enables even greater variety Exchange of equivalent sections between homologous chromosomes.Occurs at random locations along chromosome.Creates new versions of chromosomes.
27CQ#4: The cell to the right shows a diploid organism with two chromosomes (2n=2). The pictures below show some of the steps this cell may go throughduring mitosis or meiosis.A B C.D. E F G H.Place the appropriate steps in order for a cell going through mitosis. (Note: you may use just some or all of the steps.)
28CQ#5: The cell to the right shows a diploid organism with two chromosomes (2n=2). The pictures below show some of the steps this cell may go throughduring mitosis or meiosis.A B C.D. E F G H.Place the appropriate steps in order for a cell going through meiosis. (Note: you may use just some or all of the steps.)2828
29Parent #2Parent #1CQ#6: The different copies of chromosome 21 in John and Jane are shown to the right.Which of the following is a normal gamete that might be produced by either John or Jane?A B C D E
30What went wrong?Now that you’ve explained to the jury how cells normally receive the correct number of chromosomes, you need to explain whether this did not happen with John and Jane’s baby because of something the clinic doctor’s may have done.What can cause a cell to inherit the incorrect number of chromosomes?
31CQ#7: How can a cell end up with an incorrect number of chromosomes? The chromosomes do not separate correctly during mitosis or meiosis.The chromosomes are copied incorrectly during mitosis or meiosis.Cells divide too many times.The chromosomes become damaged when they are being copied.Cells eliminate chromosomes they don’t need. Sometimes this doesn’t happen.
33Parent #1Parent #2Down syndromeThe different copies of chromosome 21 for John, Jane, and their baby are shown here.Child
34CQ#8:The different copies of chromosome 21 for John, Jane, and their baby are shown here.Parent #1Parent #2When and where did themistake occur?Meiosis I of parent #1Meiosis I of parent #2Meiosis II of parent #1Meiosis II of parent #2Either Meiosis I or II of parent #1Child
35CQ#9: If you were on the jury for the malpractice trial of the doctor, what would you decide? The doctor must have done something wrong to cause cell division to have malfunctioned.The doctor could not have done anything to cause the problem.It is impossible to tell if the doctor could be at fault.
36Case closed?You’ve presented pretty conclusive evidence that the clinic was not responsible for causing Down syndrome in John and Jane’s baby. However, now comes the trickiest part of the trial. Should the clinic have alerted the couple that something might be wrong before the baby was delivered? How could the doctors have known that the baby might have be born with Down syndrome?
37How is Down syndrome detected? KaryotypingIsolate chromosomes during fetal cell division.Arrange in pairs according to size.
38CQ#10: When would the best time be to isolate chromosomes for a karyotype? G1S-phaseG2ProphaseMetaphaseAnaphaseTelophaseWhy would this time be best?
39CQ#11: Does this person have Down syndrome? Yes B. No
40A karyotype can be performed by collecting cells from the developing embryo in the first trimester using one of two procedures. Techniques for doing this slightly increase the risk of miscarriage ( %). Jane’s family had no history of Down syndrome, but John had a cousin with the disorder. A chart showing Jane’s age (red line) and the risk of having a Down syndrome child is shown below.
41CQ#12: Is the clinic liable for not testing for Down syndrome? Yes, the clinic should have tested the baby for Down syndrome.It is liable only if the clinic failed to follow suggested guidelines for when to perform the test.Yes, it doesn’t matter if the clinic was at fault or not.No, the clinic should not be held at fault for something beyond its control.
42In 2001, France's high court of appeals ruled that the parents of a boy who has Down syndrome should be compensated because the situation was not detected by the doctor during the pregnancy.In 2004, the Utah Supreme Court ruled that the parents of a 4-year-old girl with Down syndrome cannot sue a doctor for misreading prenatal tests designed to identify the disability.In 2007, a California court awarded a 34-year-old woman damages because the medical center failed to offer her the opportunity to undergo amniocentesis and Chorionic Villus Sampling early in the course of her pregnancy.
43Historically, women over age 35 or who are at risk of having a child with Down syndrome are encouraged to have amniocentesis and CVS to test for this abnormality.However, because most pregnancies occur in younger couples, 80% of Down syndrome cases occur with women under age 35. Down syndrome occurs in one out of every live births.In 2007, the American College of Obstetricians and Gynecologists recommended that every pregnant woman, regardless of age, be offered a choice of tests for this common birth defect.National Down syndrome Center:
45Slide 14Description: Replicated chromosome.Source: Derived from images at Wikimedia Commons: (Madprime) and (Magnus Manske)Clearance: Licensed in accordance with Creative Commons Attribution-Share Alike 3.0 Unported.Slide 15Description: Cell cycle stages.Source: Wikimedia CommonsLink:Clearance: Public domain.Slide 19 and Slide 20Description: Human male and female figures.Link:Slide 37Description: Spectral karyotype (SKY).Source: National Human Genome Research InstituteLink:Slide 38Description: Normal karyotype.Source: National Cancer InstituteLink:Slide 39Description: Down syndrome karyotype.Author: Christa Lese Martin, Department of Human Genetics, Emory University School of MedicineSource: Emory Genetics LaboratoryClearance: Used with permission.