Ethical Issues in Medical Genetics — MCQs
Prader-Willi syndrome and Angelman syndrome are examples of what genetic phenomenon?
Mutations are due to changes in:
Which of the following statements about gene therapy is false?
Doctor or nurse disclosing the identity of a rape victim is punishable under the following section of IPC?
DNA fingerprinting is used for paternity testing and forensic identification of suspects. Which of the following is the most accurate description of DNA fingerprinting?
What is the most important tool used in genetic engineering?
Transplantation between identical twins-
A 54-year-old man presents after a syncopal episode with no recollection of the event, and bystanders report that he regained consciousness approximately 45 seconds after falling. He has a history of bipolar disorder managed with quetiapine, and recently experienced prostatitis treated with ciprofloxacin. His other medications include lisinopril and hydrochlorothiazide for hypertension, and cyclobenzaprine and a hydrocodone/acetaminophen combination pill for low back pain. On examination, the patient is alert and oriented, with a nonfocal neurological examination and an unremarkable cardiac examination. Electrocardiogram shows nonspecific ST and T wave changes and a prolonged QT interval (QTc of 540 milliseconds). What is the best initial management approach?
Chloride receptor defect is responsible for:
What is the most common genetic abnormality in cystic fibrosis?
Ethical Issues in Medical Genetics Indian Medical PG Practice Questions and MCQs
Question 1: Prader-Willi syndrome and Angelman syndrome are examples of what genetic phenomenon?
- A. Gene Knockout
- B. Impaired DNA repair
- C. Genomic Imprinting (Correct Answer)
- D. RNA interference
Explanation: ***Genomic Imprinting*** - **Genomic imprinting** is an epigenetic phenomenon where certain genes are expressed in a **parent-of-origin-specific manner**. - In Prader-Willi syndrome, the disease results from the loss of function of specific genes on chromosome 15 (15q11-q13) inherited from the father, while Angelman syndrome results from the loss of function of a different gene (UBE3A) in the same region, but inherited from the mother. *RNA interference* - **RNA interference** is a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules. - This process is not directly responsible for the parent-of-origin-specific expression patterns observed in these syndromes. *Gene Knockout* - A **gene knockout** is a genetic technique in which an organism's genes are made inoperative. - While it involves modifying gene function, it does not explain the differential expression based on parental origin. *Impaired DNA repair* - **Impaired DNA repair** refers to defects in the mechanisms that correct DNA damage. - This can lead to increased mutations and conditions like cancer, but it is not the underlying mechanism for Prader-Willi or Angelman syndromes.
Question 2: Mutations are due to changes in:
- A. DNA nucleotide sequence (Correct Answer)
- B. RNA nucleotide sequence
- C. Amino acid sequence of ribonuclease
- D. Cell membrane
Explanation: ***DNA nucleotide sequence*** - **Mutations** are defined as changes in the **genetic material**, which is primarily composed of **DNA**. - These changes in the **nucleotide sequence** of DNA can alter the genetic code, leading to changes in **protein structure and function**. *RNA nucleotide sequence* - While RNA can have its nucleotide sequence altered, these changes are generally not considered true **mutations** in the heritable sense for most organisms. - RNA is typically a temporary molecule, and changes to its sequence are usually not passed down to subsequent generations. *Amino acid sequence of ribonuclease* - An altered **amino acid sequence** in a protein like ribonuclease is a consequence of a **mutation in the DNA**, not the mutation itself. - **Ribonucleases** are enzymes that catalyze the degradation of RNA, and their structure is determined by the **DNA sequence**. *Cell membrane* - The cell membrane is a **lipid bilayer** with embedded proteins that regulates cellular transport and communication. - While its components can be affected by genetic mutations, alterations in the cell membrane itself do not constitute the primary definition of a **mutation**.
Question 3: Which of the following statements about gene therapy is false?
- A. Gene also considered as drug
- B. Gene therapy can be used to treat some cancers.
- C. Has been tried in cystic fibrosis
- D. Gene therapy is only used for genetic disorders. (Correct Answer)
Explanation: ***Gene therapy is only used for genetic disorders.*** - This statement is **false** because gene therapy has applications beyond just genetic disorders. It is also being explored and used in the treatment of acquired diseases such as **cancer** and **infectious diseases**. - While it's a prominent approach for correcting genetic defects, its scope is much broader, involving the introduction or modification of genes to achieve a therapeutic effect in various conditions. *Gene also considered as drug* - This statement is **true**. Gene therapy products are often regulated as **drugs** or **biological products** by regulatory bodies like the FDA. - This is because they involve the delivery of genetic material that acts to modify gene expression or cell function to produce a therapeutic effect, similar to how traditional drugs work. *Has been tried in cystic fibrosis* - This statement is **true**. Gene therapy has been extensively investigated as a potential treatment for **cystic fibrosis (CF)**. - CF is caused by mutations in the **CFTR gene**, and researchers have attempted to deliver functional copies of this gene to the affected cells, particularly in the lungs, to correct the underlying defect. *Gene therapy can be used to treat some cancers.* - This statement is **true**. Gene therapy is an active area of research and treatment for various **cancers** [1]. - Approaches include introducing genes that make cancer cells more susceptible to chemotherapy, enhancing the immune system's ability to fight cancer, or directly killing cancer cells through gene delivery [1].
Question 4: Doctor or nurse disclosing the identity of a rape victim is punishable under the following section of IPC?
- A. Section 224A
- B. Section 226A
- C. Section 222A
- D. Section 228A (Correct Answer)
Explanation: ***Section 228A IPC*** - This section of the Indian Penal Code specifically deals with the **disclosure of the identity of a victim of rape and certain sexual offenses** (Sections 376, 376A, 376AB, 376B, 376C, 376D, 376DA, 376DB, 376E). - Making public the name or any matter that can reveal the identity of a rape victim by **any person, including doctors and nurses**, is a punishable offense. - **Punishment**: Imprisonment up to **2 years** and fine. - **Exception**: Disclosure is permitted only to authorized persons like police officers for investigation purposes. - **Important**: This is now covered under **Section 72 of Bharatiya Nyaya Sanhita (BNS) 2023**, which replaced the IPC. *Section 224A* - This is **not a valid or recognized provision** within the Indian Penal Code. - It does not relate to offenses concerning privacy or the identity of sexual assault victims. *Section 226A* - This is **not a valid or recognized provision** within the Indian Penal Code. - It does not pertain to the confidentiality of victims of sexual offenses. *Section 222A* - This is **not a valid or recognized provision** within the Indian Penal Code. - There is no such specific section addressing disclosure of victim identity in the IPC.
Question 5: DNA fingerprinting is used for paternity testing and forensic identification of suspects. Which of the following is the most accurate description of DNA fingerprinting?
- A. DNA is isolated from blood, skin, or sperm and its fragment size distribution is analyzed by gel electrophoresis
- B. DNA can be isolated from blood, skin, or sperm and analyzed for variable patterns of restriction fragments arising from tandemly repeated sequences (microsatellites) (Correct Answer)
- C. DNA is isolated from blood, skin, or sperm and hybridized with probes from the HLA locus to visualize HLA gene patterns
- D. DNA is copied from blood, skin, or sperm RNA using reverse transcriptase and analyzed for the pattern of complementary DNAs
Explanation: ***DNA can be isolated from blood, skin, or sperm and analyzed for variable patterns of restriction fragments arising from tandemly repeated sequences (microsatellites)*** - **DNA fingerprinting**, also known as **DNA profiling**, primarily relies on the analysis of highly variable regions of DNA, specifically **tandemly repeated sequences** like microsatellites or STRs (short tandem repeats). - These regions exhibit individual-specific variation in the number of repeats, which, when cut by **restriction enzymes**, produce fragments of varying lengths, generating a unique **restriction fragment length polymorphism (RFLP)** pattern. *DNA is isolated from blood, skin, or sperm and its fragment size distribution is analyzed by gel electrophoresis* - While **gel electrophoresis** is a part of the process to separate DNA fragments by size, this option is incomplete as it doesn't specify *what* fragments are being analyzed or *why* they differ between individuals. - The crucial aspect of DNA fingerprinting is the analysis of **variable short tandem repeats (STRs)** or **variable number tandem repeats (VNTRs)**, which generate these distinct fragment sizes. *DNA is isolated from blood, skin, or sperm and hybridized with probes from the HLA locus to visualize HLA gene patterns* - **HLA (Human Leukocyte Antigen)** typing is used for tissue matching in transplantation and for studying autoimmune diseases, but it is **not the primary method** for DNA fingerprinting in paternity or forensic cases. - While HLA genes are polymorphic, the specific patterns examined in DNA fingerprinting are typically **non-coding repetitive sequences** which are more variable and less complex to interpret for individual identification. *DNA is copied from blood, skin, or sperm RNA using reverse transcriptase and analyzed for the pattern of complementary DNAs* - **DNA fingerprinting** directly analyzes **genomic DNA**, not RNA. The process of reverse transcribing RNA into cDNA is typically used for studying gene expression. - **RNA is less stable** than DNA and does not contain the same highly variable **repetitive sequences** (like STRs or VNTRs) that are fundamental to DNA fingerprinting.
Question 6: What is the most important tool used in genetic engineering?
- A. Topoisomerase
- B. DNA Ligase
- C. Restriction endonuclease (Correct Answer)
- D. Helicase
Explanation: ***Restriction endonuclease*** - **Restriction endonucleases** are crucial for genetic engineering as they specifically cut DNA at particular recognition sites, allowing the insertion or deletion of genes. - This precise cutting ability is fundamental for creating **recombinant DNA** molecules. *Helicase* - **Helicase** is primarily involved in unwinding the DNA double helix during processes like DNA replication and transcription. - While essential for cellular functions, it does not directly manipulate DNA for gene insertion or modification in the way restriction enzymes do. *Topoisomerase* - **Topoisomerase** enzymes are responsible for managing DNA supercoiling, preventing tangling during DNA replication and transcription by cutting and rejoining DNA strands. - It plays a role in DNA structure but is not directly used for targeted gene editing or insertion. *DNA Ligase* - **DNA ligase** is essential for joining DNA fragments, which is a critical step in genetic engineering after restriction endonucleases have cut the DNA. - However, while it acts as a "molecular glue" to seal nicks and re-form phosphodiester bonds, it cannot initiate the precise cutting required to isolate genes.
Question 7: Transplantation between identical twins-
- A. Xenograft
- B. Autograft
- C. Isograft (Correct Answer)
- D. Allograft
Explanation: ***Isograft*** - An **isograft** refers to a transplant between **genetically identical individuals**, such as identical twins, thus minimizing immune rejection [1]. - Due to the identical genetic makeup, the recipient's immune system will not recognize the transplanted tissue as foreign, making **immunosuppression unnecessary** [1]. *Xenograft* - A **xenograft** involves transplantation of tissues or organs between **different species**, for example, from a pig to a human. - These grafts typically face severe and rapid **immune rejection** due to significant genetic differences between the donor and recipient species. *Autograft* - An **autograft** is a transplant of tissue from **one part of an individual's body to another part of the same individual**. - This type of graft has no risk of rejection as the tissue is genetically identical to the recipient's own tissue [2]. *Allograft* - An **allograft** is a transplant between **genetically non-identical individuals of the same species**, such as between two non-twin humans. - These grafts always require **immunosuppressive therapy** to prevent rejection due to genetic differences, though rejection rates vary based on HLA matching [1].
Question 8: A 54-year-old man presents after a syncopal episode with no recollection of the event, and bystanders report that he regained consciousness approximately 45 seconds after falling. He has a history of bipolar disorder managed with quetiapine, and recently experienced prostatitis treated with ciprofloxacin. His other medications include lisinopril and hydrochlorothiazide for hypertension, and cyclobenzaprine and a hydrocodone/acetaminophen combination pill for low back pain. On examination, the patient is alert and oriented, with a nonfocal neurological examination and an unremarkable cardiac examination. Electrocardiogram shows nonspecific ST and T wave changes and a prolonged QT interval (QTc of 540 milliseconds). What is the best initial management approach?
- A. Admit for permanent implantable cardioverter-defibrillator (ICD)
- B. Admit and begin amiodarone infusion
- C. Refer for genetic counseling
- D. Admit the patient for telemetry and evaluate for reversible causes of QT prolongation (Correct Answer)
Explanation: ***Admit the patient for telemetry and evaluate for reversible causes of QT prolongation*** * The patient experienced a **syncopal episode** with a **prolonged QT interval (QTc of 540 ms)**, which significantly increases the risk of **Torsade de Pointes (TdP)** and sudden cardiac death [1]. * **Telemetry monitoring** is crucial to detect arrhythmias, and identifying and removing **QT-prolonging medications** (quetiapine, ciprofloxacin, hydrocodone) and correcting **electrolyte imbalances** are essential initial steps [1]. *Admit for permanent implantable cardioverter-defibrillator (ICD)* * While an ICD is used for prevention of sudden cardiac death in high-risk patients, it's generally considered after **reversible causes of QT prolongation** have been addressed and the patient remains at high risk or has recurrent **life-threatening arrhythmias**. * Implanting an ICD without first attempting to manage the modifiable risk factors like certain medications or electrolyte imbalances would be premature. *Admit and begin amiodarone infusion* * **Amiodarone** is an **antiarrhythmic drug** that itself can **prolong the QT interval**, which would exacerbate the patient's existing risk for TdP. * This medication would be contraindicated in the presence of an already prolonged QT interval due to the increased risk of potentially fatal arrhythmias. *Refer for genetic counseling* * While **congenital long QT syndrome** can cause profound QT prolongation, **acquired causes** (medications, electrolyte abnormalities) are far more common, especially given the patient's extensive medication list. * Genetic counseling may be considered if reversible causes are ruled out or if there's a strong family history, but it is not the immediate best management for an acute syncopal episode with acquired QT prolongation.
Question 9: Chloride receptor defect is responsible for:
- A. Cystic fibrosis (Correct Answer)
- B. Alpha-1 antitrypsin deficiency
- C. Wilson's disease
- D. Hemochromatosis
Explanation: Cystic fibrosis - Cystic fibrosis (CF) is caused by mutations in the **CFTR gene**, which encodes the **cystic fibrosis transmembrane conductance regulator protein**, a **chloride channel** [1]. - A defective CFTR protein leads to abnormal chloride transport across epithelial cells, resulting in thick, viscous secretions in various organs like the lungs, pancreas, and sweat glands [1]. *Alpha-1 antitrypsin deficiency* - This condition is due to a genetic defect in the production of **alpha-1 antitrypsin**, a protective enzyme. - It primarily affects the lungs (emphysema) and liver (cirrhosis) and is not related to chloride receptor function. *Wilson's disease* - Wilson's disease is an autosomal recessive disorder characterized by accumulation of **copper** in various tissues, especially the liver, brain, and eyes. - It is caused by mutations in the **ATP7B gene**, which codes for a copper-transporting ATPase, not a chloride channel. *Hemochromatosis* - Hemochromatosis is a disorder of **iron overload** in the body, primarily due to excessive absorption of dietary iron. - It is often caused by mutations in the **HFE gene** and does not involve chloride receptor defects.
Question 10: What is the most common genetic abnormality in cystic fibrosis?
- A. ΔF508 (Correct Answer)
- B. R117H
- C. G551D
- D. G542X
Explanation: ***ΔF508*** - This mutation accounts for approximately **70% of all cystic fibrosis (CF) cases** worldwide, making it the most common genetic abnormality [1]. - It results in the deletion of a **phenylalanine residue** at position 508 in the **CFTR protein**, leading to misfolding and degradation [1]. *R117H mutation* - This is a rare **splice-site mutation** that can cause a milder form of CF or CFTR-related disorders. - It results in reduced CFTR protein function but is not the most common mutation. *G551D mutation* - This mutation is a **class III gating mutation**, meaning it impairs the opening of the **chloride channel** rather than its synthesis or trafficking. - It is relatively rare and is specifically targeted by CFTR modulator therapies like ivacaftor. *G542X mutation* - This is a **class I nonsense mutation** that introduces a premature stop codon, leading to a truncated and non-functional CFTR protein [1]. - While it causes severe CF, it is less common than the ΔF508 mutation. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, p. 476.
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