The frequencies of the four alleles contributed to the child by possible father F1 in Problem 7 are 0.18, 0.23, 0.13, and 0.14. Calculate the Combined Paternity Index (CPI) for the four genes in this analysis.
Table of contents
- 1. Introduction to Genetics51m
- 2. Mendel's Laws of Inheritance3h 37m
- 3. Extensions to Mendelian Inheritance2h 41m
- 4. Genetic Mapping and Linkage2h 28m
- 5. Genetics of Bacteria and Viruses1h 21m
- 6. Chromosomal Variation1h 48m
- 7. DNA and Chromosome Structure56m
- 8. DNA Replication1h 10m
- 9. Mitosis and Meiosis1h 34m
- 10. Transcription1h 0m
- 11. Translation58m
- 12. Gene Regulation in Prokaryotes1h 19m
- 13. Gene Regulation in Eukaryotes44m
- 14. Genetic Control of Development44m
- 15. Genomes and Genomics1h 50m
- 16. Transposable Elements47m
- 17. Mutation, Repair, and Recombination1h 6m
- 18. Molecular Genetic Tools19m
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
18. Molecular Genetic Tools
Methods for Analyzing DNA
Problem 11
Textbook Question
Maternal blood tests for three pregnant women revealed they would be having boys, yet subsequent ultrasound images showed all three were pregnant with girls. In each case Y chromosome sequences in each mother's blood originated from transplanted organs they had received from men! This demonstrates one dramatic example of a limitation of genetic analysis of maternal blood samples. What kind of information could have been collected from each mother in advance of these tests to better inform physicians prior to performing each test?

1
Step 1: Understand the context of the problem. The maternal blood test detects Y chromosome sequences, which are typically associated with male fetuses. However, in this case, the Y chromosome sequences originated from transplanted organs received from male donors, not the fetus.
Step 2: Recognize the limitation of the test. The maternal blood test cannot distinguish between Y chromosome sequences from the fetus and those from other sources, such as transplanted organs. This highlights the importance of considering external factors that may affect genetic analysis results.
Step 3: Collect medical history of the mother. Physicians should gather detailed information about the mother's medical history, including any organ transplants, blood transfusions, or other procedures that could introduce foreign DNA into her bloodstream.
Step 4: Perform additional genetic tests. To confirm the origin of the Y chromosome sequences, physicians could use more specific tests, such as analyzing the genetic markers unique to the fetus or comparing the detected sequences to the donor's DNA profile.
Step 5: Educate and inform the patient. Physicians should explain the limitations of maternal blood tests and discuss alternative methods for determining fetal sex, such as ultrasound imaging or amniocentesis, especially in cases where external DNA sources are present.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Fetal DNA in Maternal Blood
Fetal DNA can be found in the maternal bloodstream, allowing for non-invasive prenatal testing. This DNA is typically a mixture of maternal and fetal genetic material, and its analysis can provide information about the fetus's sex and potential genetic disorders. However, the presence of male DNA in maternal blood can lead to misleading results, especially if the mother has received male organ transplants.
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Transplant Immunology
Transplant immunology studies how the immune system responds to transplanted organs. When a woman receives a male organ transplant, Y chromosome sequences from the donor can circulate in her blood. This can complicate genetic testing, as the presence of these sequences may be misinterpreted as indicating a male fetus, highlighting the importance of understanding a patient's medical history before genetic testing.
Pre-Test Genetic Counseling
Pre-test genetic counseling involves discussing the implications, limitations, and potential outcomes of genetic tests with patients. This process can help identify any factors that may affect test results, such as previous organ transplants or genetic conditions in the family. By gathering comprehensive medical histories, healthcare providers can better inform patients and interpret test results more accurately.
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