Precision Medicine — MCQs
Phenotypic expression of a gene depending on the parent of origin is referred to as:
Mutations are due to changes in:
An example of an IMiD (immunomodulatory derivative of thalidomide) is:
Lenalidomide co-administration with which other drug increases the risk of thrombosis?
Osimertinib is used in NSCLC with which mutation?
In which phase of clinical trials is drug dosing typically determined?
Which of the following is recognized as the apex national institute of ophthalmology in India?
Which of the following techniques is used for the detection of variations in DNA sequence and gene expression?
What is the treatment for HER-2 positive trastuzumab resistant breast cancer?
A hospital implements blockchain technology for maintaining electronic health records. Compared to traditional centralized database systems, what is the primary advantage that justifies this innovation from a healthcare quality perspective?
Precision Medicine Indian Medical PG Practice Questions and MCQs
Question 1: Phenotypic expression of a gene depending on the parent of origin is referred to as:
- A. Genomic imprinting (parent-of-origin gene expression) (Correct Answer)
- B. Mosaic genetic variation
- C. Nonpenetrance of genotype
- D. Genetic anticipation
Explanation: ***Genomic imprinting (parent-of-origin gene expression)*** - **Genomic imprinting** is an epigenetic phenomenon where gene expression is dependent on whether the gene was inherited from the mother or the father. - This results in monoallelic expression of specific genes, with only one copy (maternal or paternal) being active. *Mosaic genetic variation* - **Mosaicism** refers to the presence of two or more populations of genetically different cells in one individual, all derived from a single zygote. - This typically arises from a somatic mutation during development, not from differential expression based on parental origin. *Nonpenetrance of genotype* - **Nonpenetrance** occurs when individuals carrying a disease-causing genotype do not express the associated phenotype. - This concept relates to the presence or absence of a phenotype, not the differential expression based on parental origin. *Genetic anticipation* - **Genetic anticipation** is the phenomenon where the symptoms of a genetic disorder become more severe and/or appear at an earlier age in successive generations. - This is commonly observed in disorders caused by expansions of trinucleotide repeats, such as Huntington's disease, and is distinct from parent-of-origin gene expression.
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: An example of an IMiD (immunomodulatory derivative of thalidomide) is:
- A. Palivizumab
- B. Lenalidomide (Correct Answer)
- C. Ribavirin
- D. None of the options
Explanation: ***Lenalidomide*** - **Lenalidomide** is a well-known **immunomodulatory imide drug (IMiD)** derived from thalidomide, commonly used in the treatment of multiple myeloma and myelodysplastic syndromes. - IMiDs are characterized by their ability to modulate immune responses, enhance T-cell and NK-cell activity, and have direct anti-cancer effects through inhibition of angiogenesis and tumor cell proliferation. *Palivizumab* - **Palivizumab** is a **monoclonal antibody** that targets the fusion protein of respiratory syncytial virus (RSV), used for prophylaxis in high-risk infants. - It is not classified as an immunomodulatory imide drug and has a completely different structure and mechanism of action. *Ribavirin* - **Ribavirin** is an **antiviral agent** primarily used to treat chronic hepatitis C virus infection and respiratory syncytial virus. - Its mechanism of action is antiviral, not immunomodulatory in the same way as IMiDs. *None of the options* - This option is incorrect because **Lenalidomide** is indeed an example of an IMiD, making the statement false. - At least one correct answer exists among the given choices.
Question 4: Lenalidomide co-administration with which other drug increases the risk of thrombosis?
- A. Alcohol
- B. Barbiturates
- C. Antibiotics
- D. Glucocorticoids (Correct Answer)
Explanation: ***Glucocorticoids*** - Co-administration of **lenalidomide** with **dexamethasone** (a glucocorticoid) significantly increases the risk of **venous thromboembolism (VTE)** in patients with **multiple myeloma**. - This combination therapy, though effective, necessitates **thromboprophylaxis** to mitigate the heightened risk of blood clots. *Alcohol* - While alcohol can affect drug metabolism and contribute to bleeding risk, it is not specifically known to increase the **thrombotic risk** when co-administered with lenalidomide. - Its primary interactions with lenalidomide are not related to clotting. *Barbiturates* - **Barbiturates** are strong **CYP450 enzyme inducers**, which can alter the metabolism of many drugs by decreasing their plasma concentrations. - They are not directly associated with an increased **thrombosis risk** when combined with lenalidomide. *Antibiotics* - Some antibiotics can interact with coagulation pathways or affect vitamin K levels, but there is no specific evidence linking **antibiotic co-administration** with an increased **thrombotic risk** when taken with lenalidomide. - Any potential interactions are generally minor and not related to thrombosis risk.
Question 5: Osimertinib is used in NSCLC with which mutation?
- A. L858R mutation
- B. M790T mutation
- C. T890M mutation
- D. T790M mutation (Correct Answer)
Explanation: ***T790M mutation*** - **Osimertinib** is a third-generation **EGFR tyrosine kinase inhibitor (TKI)** specifically designed to overcome resistance to earlier generation EGFR TKIs. - The **T790M mutation** in the EGFR gene is the most common mechanism of acquired resistance to first and second-generation EGFR TKIs in non-small cell lung cancer (NSCLC). *L858R mutation* - The **L858R mutation** is an activating **EGFR mutation** typically sensitive to first and second-generation EGFR TKIs. - While patients with **L858R** may eventually develop resistance, **osimertinib** is primarily used in the setting of acquired resistance, often mediated by **T790M**. *M790T mutation* - This is not a recognized common or clinically significant activating or resistance mutation in the **EGFR gene** for NSCLC. - The correct resistance mutation that **osimertinib** targets is **T790M**, not **M790T**. *T890M mutation* - This is a typographical error for the clinically relevant **T790M mutation**. - The number sequence is critical for identifying specific amino acid substitutions in gene mutations.
Question 6: In which phase of clinical trials is drug dosing typically determined?
- A. Phase 1 (Correct Answer)
- B. Phase 2
- C. Phase 3
- D. Phase 4
- E. Phase 0
Explanation: ***Phase 1*** - This phase involves a small group of **healthy volunteers** to assess the drug's safety, **pharmacokinetics (PK)**, and establish an initial dosing range. - The primary goal is to determine a **safe dosage level**, establish the **maximum tolerated dose (MTD)**, and identify potential side effects. - This is where drug dosing is **typically determined**. *Phase 0* - This is an exploratory phase involving **microdosing** studies with subtherapeutic doses. - The goal is to gather preliminary PK/PD data, but **not to determine therapeutic dosing**. *Phase 2* - This phase involves a larger group of **patients** with the condition to be treated. - The main goal is to evaluate the drug's **effectiveness** and further assess safety, but not primarily to determine initial dosing. *Phase 3* - This phase involves a large number of patients across multiple sites to confirm the drug's **efficacy** and monitor side effects in a broader population. - Dosing strategies have generally been established in earlier phases, and this phase primarily validates them. *Phase 4* - This phase occurs **after a drug has been approved** and marketed. - It involves ongoing surveillance to monitor long-term effects, collect additional information on safety, and identify new uses, but not initial dose determination.
Question 7: Which of the following is recognized as the apex national institute of ophthalmology in India?
- A. Dr. R P Centre for Ophthalmic Sciences, AIIMS, New Delhi (Correct Answer)
- B. Sankara Nethralaya, Chennai
- C. Advanced Eye Care, PGIMER, Chandigarh
- D. Regional Institute of Ophthalmology (RIO)
Explanation: ***Dr. R P Centre for Ophthalmic Sciences, AIIMS, New Delhi*** - Dr. R P Centre for Ophthalmic Sciences at AIIMS, New Delhi, is widely recognized as the **apex national institute for ophthalmology in India**, leading in patient care, research, and education. - Its status is attributed to its comprehensive facilities, advanced research, and significant contributions to **ophthalmic training and healthcare policy** at a national level. *Shankara Netralaya, Chennai* - Though a highly reputed and large-scale eye hospital, Sankara Nethralaya is a **private, not-for-profit institution** and does not hold the official "apex national institute" designation. - It is renowned for its clinical excellence and research but primarily operates as a **tertiary care center** rather than a national apex body. *Advanced Eye Care, PGIMER, Chandigarh* - The Advanced Eye Centre at PGIMER, Chandigarh, is a prominent **regional institute** and a center of excellence in ophthalmology in North India. - While it provides high-quality care and education, it is not designated as the **national apex body** for ophthalmology across India. *Regional Institute of Ophthalmology (RIO)* - There are several Regional Institutes of Ophthalmology (RIOs) located across different states in India, established to provide **specialized eye care** and training within their respective regions. - Each RIO serves as a **regional hub**, but no single RIO represents the overall national apex institution for ophthalmology in India.
Question 8: Which of the following techniques is used for the detection of variations in DNA sequence and gene expression?
- A. Southern blot
- B. Western blot
- C. Microarray (Correct Answer)
- D. Northern blot
Explanation: ***Microarray*** - **Microarrays** are designed to detect thousands of DNA or RNA sequences simultaneously, making them ideal for analyzing **gene expression profiles** and identifying **sequence variations** like SNPs. - They involve hybridizing labeled sample DNA/RNA to probes fixed on a solid surface, with the intensity of hybridization indicating the presence or abundance of specific sequences. *Northern blot* - The **Northern blot** technique is primarily used to study **gene expression** by detecting specific **RNA sequences** in a sample. - It does not directly analyze DNA sequence variations. *Southern blot* - The **Southern blot** is a molecular biology method used to detect specific **DNA sequences** in DNA samples. - While it can identify large-scale DNA rearrangements or deletions, it is not optimized for simultaneous detection of multiple gene expression levels or subtle sequence variations. *Western blot* - The **Western blot** is used to detect specific **proteins** in a sample. - It analyzes protein expression levels and modifications and is not designed for the detection of DNA sequence variations or gene expression at the RNA level.
Question 9: What is the treatment for HER-2 positive trastuzumab resistant breast cancer?
- A. Sorafenib
- B. Lapatinib (Correct Answer)
- C. Vemurafenib
- D. Erlotinib
Explanation: ***Lapatinib*** - Lapatinib is a **dual tyrosine kinase inhibitor** that targets both **HER-2** and **epidermal growth factor receptor (EGFR)**, acting as a **small molecule inhibitor** that binds to the intracellular domain of these receptors. - Unlike trastuzumab (a monoclonal antibody targeting the extracellular domain), Lapatinib's **intracellular mechanism of action** allows it to overcome common mechanisms of trastuzumab resistance, such as receptor truncation or masking of the extracellular epitope. - It is specifically approved for the treatment of **HER-2 positive metastatic breast cancer** in combination with capecitabine after progression on trastuzumab-containing regimens. *Sorafenib* - Sorafenib is a **multi-kinase inhibitor** primarily targeting RAF, VEGFR, and PDGFR, and is used in renal cell carcinoma and hepatocellular carcinoma. - It does not specifically target HER-2 and is **not indicated** for HER-2 positive trastuzumab-resistant breast cancer. *Vemurafenib* - Vemurafenib is a **BRAF inhibitor** used for treating BRAF V600E mutation-positive melanoma. - This drug has no direct indications or demonstrated efficacy for **HER-2 positive breast cancer** and does not address trastuzumab resistance mechanisms. *Erlotinib* - Erlotinib is an **EGFR tyrosine kinase inhibitor** primarily used for non-small cell lung cancer with activating EGFR mutations. - While it targets EGFR, it does **not effectively target HER-2** and lacks the dual inhibition necessary to overcome trastuzumab resistance in HER-2 positive breast cancer.
Question 10: A hospital implements blockchain technology for maintaining electronic health records. Compared to traditional centralized database systems, what is the primary advantage that justifies this innovation from a healthcare quality perspective?
- A. Faster data retrieval for clinical decision-making
- B. Enhanced data integrity through immutable distributed ledger (Correct Answer)
- C. Reduced storage costs due to distributed architecture
- D. Simplified user interface for healthcare providers
Explanation: ***Enhanced data integrity through immutable distributed ledger*** - The primary feature of **blockchain** is its **immutability**, meaning once a record is added to the ledger, it cannot be altered without consensus from the network. - This ensures **data integrity** and creates a permanent, transparent **audit trail**, which is critical for reducing medical errors and preventing unauthorized tampering with health records. *Faster data retrieval for clinical decision-making* - Blockchain architecture often involves **consensus protocols** and distributed verification, which can actually make data retrieval or processing **slower** than traditional centralized databases. - The innovation's value lies in **security and trust**, not necessarily in the raw speed of clinical inquiry compared to high-speed SQL databases. *Reduced storage costs due to distributed architecture* - In a blockchain, the ledger is **replicated** across multiple nodes, which typically leads to **higher storage requirements** and costs rather than lower ones. - Each participating node must maintain a copy of the transactions, making the architecture inherently **more expensive** in terms of data redundancy. *Simplified user interface for healthcare providers* - Blockchain is a **back-end infrastructure** technology and does not inherently influence or improve the **user interface (UI)** or front-end experience. - The complexity of managing **cryptographic keys** can sometimes make the system more difficult for non-technical users to navigate compared to traditional systems.
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