Genetic Testing and Counseling — MCQs
Which banding technique is most commonly used for karyotyping?
Doctor or nurse disclosing the identity of a rape victim is punishable under the following section of IPC?
Which test is not required for Turner mosaic syndrome?
Which of the following represents the current recommendation for offering screening for Down's syndrome during pregnancy?
Among the biochemical methods of genetic engineering, the Western Blot detects:
Most appropriate time for chorionic villus sampling in pregnancy is:
Gluten sensitive enteropathy is strongly associated with:-
Wilson's disease has which of the following inheritance?
24 yr old mother with 7 week POG presents to ANC OPD with accidental low-dose radiation exposure. What is the most appropriate immediate management?
Which of the following conditions is associated with ectopia lentis?
Genetic Testing and Counseling Indian Medical PG Practice Questions and MCQs
Question 1: Which banding technique is most commonly used for karyotyping?
- A. G banding (Correct Answer)
- B. Q banding
- C. C banding
- D. R banding
Explanation: ***G banding*** - This method is the **most widely used** technique for karyotyping, allowing clear visualization of chromosome bands under light microscopy [1][2]. - G banding helps in identifying **chromosomal abnormalities** and is routinely utilized in clinical genetics [2]. *C banding* - Primarily highlights the **centromeric regions** of chromosomes, but is less common than G banding for overall karyotyping. - Does not provide a full **karyotype view**, making it less suitable for routine analysis. *R banding* - Useful for providing **reverse staining**, which shows the bands in a different manner but is not as commonly employed in clinical settings. - Typically used to analyze specific **chromosomal translocations**, rather than routine karyotyping. *Q banding* - This technique involves **fluorescent microscopy** to visualize chromosomes but is not as prevalent for basic karyotyping. - Mainly used for detecting **specific chromosomal anomalies**, not the standard karyotype assessment. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 54-55. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 167-168.
Question 2: 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 3: Which test is not required for Turner mosaic syndrome?
- A. Audiometry
- B. Oral glucose tolerance test
- C. Echo
- D. ANA (Correct Answer)
Explanation: ***ANA*** - **Antinuclear antibody (ANA)** testing is primarily used for diagnosing autoimmune diseases like **systemic lupus erythematosus** and is not routinely required for the management of Turner mosaic syndrome. - While autoimmune conditions can rarely co-occur, ANA is not a standard screening or diagnostic test for the common complications of Turner syndrome. *Audiometry* - **Audiometry** is recommended for Turner syndrome patients due to an increased risk of **hearing loss**, particularly **sensorineural hearing loss**. - Regular monitoring helps detect and manage hearing impairments early, which can affect development and quality of life. *Oral glucose tolerance test* - Patients with Turner syndrome have an increased risk of developing **glucose intolerance** and **type 2 diabetes mellitus**. - An **oral glucose tolerance test (OGTT)** is important for screening and early detection of these metabolic abnormalities. *Echo* - **Echocardiography** is crucial for evaluating potential **cardiovascular abnormalities**, which are common in Turner syndrome. - These can include **bicuspid aortic valve**, **coarctation of the aorta**, and other structural heart defects.
Question 4: Which of the following represents the current recommendation for offering screening for Down's syndrome during pregnancy?
- A. 35
- B. No screening necessary
- C. 30
- D. All in the reproductive age group (Correct Answer)
Explanation: ***All in the reproductive age group*** - The American College of Obstetricians and Gynecologists (ACOG) and other major medical bodies recommend that **all pregnant women**, regardless of age, be offered **screening for Down syndrome** and other aneuploidies. - This recommendation reflects the principle of **patient autonomy** and the availability of safe and effective screening methods for all pregnancies, not just those considered high-risk based on maternal age. *30* - While the risk of Down syndrome increases with maternal age, **screening is not exclusively recommended for women aged 30**; rather, it is offered to all pregnant women. - Focusing only on this age group would **miss cases** in younger women and limit informed decision-making. *35* - Historically, **maternal age 35** was considered the threshold for offering invasive diagnostic testing due to the significantly increased risk of Down syndrome. - However, current guidelines emphasize universal screening, as a substantial number of babies with Down syndrome are born to women **younger than 35** due to higher birth rates in this group. *No screening necessary* - This option is incorrect as **screening is routinely offered** to all pregnant women to provide information about the risk of conditions like Down syndrome. - Deciding to forgo screening or diagnostic testing is a personal choice, but the **option to screen should always be available** to the patient.
Question 5: Among the biochemical methods of genetic engineering, the Western Blot detects:
- A. Protein (Correct Answer)
- B. DNA
- C. mRNA
- D. RNA
Explanation: ***Protein*** - **Western blot** (also known as protein immunoblot) is a widely used analytical technique in molecular biology and immunogenetics to detect specific **proteins** in a sample. - It involves separating proteins by size using **gel electrophoresis**, transferring them to a membrane, and then detecting the protein of interest using specific antibodies. *DNA* - **DNA** is typically detected using techniques like **Southern blot** or **PCR (Polymerase Chain Reaction)**. - Western blot is not designed to recognize nucleic acids, but rather uses antibodies that bind to specific protein epitopes. *mRNA* - **mRNA** (messenger RNA) is analyzed using methods like **Northern blot** or **RT-PCR (Reverse Transcription PCR)**. - These techniques specifically target RNA sequences and involve RNA extraction, separation, and hybridization with complementary probes. *RNA* - The general term **RNA** encompasses various types including mRNA, tRNA, and rRNA; Northern blot is the most common method for detecting specific RNA molecules. - Western blot, being an antibody-based assay, is specific for the detection and quantification of **proteins**.
Question 6: Most appropriate time for chorionic villus sampling in pregnancy is:
- A. 16-18 weeks
- B. 16-20 weeks
- C. 8-10 weeks
- D. 10-13 weeks (Correct Answer)
Explanation: ***10-13 weeks*** - Chorionic villus sampling (CVS) is optimally performed between **10 and 13 completed weeks of gestation**. - This timing allows for **earlier diagnosis** of chromosomal abnormalities compared to amniocentesis, enabling more time for decision-making. *16-18 weeks* - This timeframe is typically used for **amniocentesis**, which is performed later in pregnancy. - Performing CVS at this stage is **outside the optimal window** and carries a higher risk profile for CVS specifically. *16-20 weeks* - This period is also generally recommended for **amniocentesis**, not chorionic villus sampling. - Delaying CVS until this point **reduces the advantage** of early diagnosis and may increase procedural risks. *8-10 weeks* - Performing CVS **before 10 weeks of gestation** is associated with a **higher risk of limb reduction defects** in the fetus. - Due to this significant risk, CVS is generally **contraindicated** before 10 weeks.
Question 7: Gluten sensitive enteropathy is strongly associated with:-
- A. HLA-DQ2 (Correct Answer)
- B. HLA-DQ3
- C. Blood group B
- D. HLA-DR4
Explanation: ### HLA-DQ2 - **HLA-DQ2** is the most significant **genetic risk factor** for **celiac disease** (gluten-sensitive enteropathy), present in about 90-95% of patients [1]. - Its presence is necessary, though not sufficient, for the development of the disease, playing a crucial role in immune response to **gluten peptides** [1]. ### HLA-DQ3 - While other HLA-DQ alleles exist, **HLA-DQ3** is not primarily associated with celiac disease. - The dominant susceptibility alleles are **HLA-DQ2** and, to a lesser extent, **HLA-DQ8** [1]. ### Blood group B - There is **no established strong association** between **blood group B** and the development of celiac disease. - Blood groups are primarily related to red blood cell antigens, not directly to autoimmune conditions like celiac disease. ### HLA-DR4 - **HLA-DR4** is mainly associated with other autoimmune diseases, particularly **rheumatoid arthritis**, and is not a primary genetic marker for celiac disease. - Although it's part of the MHC class II locus, its specific alleles like **HLA-DQ2** and **HLA-DQ8** are more relevant for celiac disease [1].
Question 8: Wilson's disease has which of the following inheritance?
- A. It is an acquired disease
- B. Autosomal recessive (Correct Answer)
- C. X-linked recessive
- D. Autosomal dominant
Explanation: ***Autosomal recessive*** - Wilson's disease is caused by mutations in the **ATP7B gene**, which codes for a copper-transporting ATPase. - For an individual to develop the disease, they must inherit **two copies of the mutated gene**, one from each parent. *It is an acquired disease* - Wilson's disease is a **genetic disorder**, meaning it is inherited, not acquired through environmental factors or lifestyle [1]. - While symptoms may manifest later in life, the underlying cause is a **predisposing genetic mutation** [1]. *X-linked recessive* - X-linked recessive disorders primarily affect males as they have only one X chromosome; however, Wilson's disease **affects both sexes equally**. - The gene responsible for Wilson's disease, **ATP7B**, is located on **chromosome 13**, an autosome, not on the X chromosome. *Autosomal dominant* - In autosomal dominant inheritance, only **one copy of the mutated gene** is sufficient to cause the disease, and it is usually seen in every generation. - Wilson's disease requires **two mutated copies** of the gene to manifest, and carriers (heterozygotes) are typically asymptomatic.
Question 9: 24 yr old mother with 7 week POG presents to ANC OPD with accidental low-dose radiation exposure. What is the most appropriate immediate management?
- A. Reassure and continue pregnancy (Correct Answer)
- B. Perform detailed fetal anomaly scan
- C. Advise medical termination of pregnancy
- D. Advise genetic counseling and testing
Explanation: ***Reassure and continue pregnancy*** - **Low-dose radiation exposure** (typically defined as <50 mGy) during pregnancy is generally associated with a very low risk of fetal anomalies or adverse outcomes. The patient should be reassured that the risk to the fetus is minimal. - The threshold for concern for teratogenic effects from radiation is significantly higher than a low dose, and **medical termination of pregnancy** is not indicated in such cases. - This is the most appropriate **immediate management** for accidental low-dose radiation exposure at 7 weeks gestation. *Perform detailed fetal anomaly scan* - While anomaly scans are part of routine prenatal care, performing an immediate, detailed scan solely due to **low-dose radiation exposure** at 7 weeks is not the most appropriate *immediate* management. The risk of anomalies from such exposure is extremely low and unlikely to be detectable at 7 weeks. - A more detailed scan may be considered at later gestational ages (e.g., 18-20 weeks) as part of standard care, but not as an emergency response to low-dose exposure. *Advise medical termination of pregnancy* - Medical termination is **not indicated** for accidental **low-dose radiation exposure**. Termination is only considered in cases of *extremely high* and confirmed doses (e.g., >100 mGy), which carry a significant risk of severe fetal anomalies or mortality. - Such high doses are rare in accidental exposures and would necessitate a thorough dose assessment by a radiation physicist before considering any drastic measures. - Since the scenario specifies low-dose exposure, termination would be inappropriate and potentially harmful counseling. *Advise genetic counseling and testing* - **Genetic counseling** and testing would be indicated for known genetic risks, advanced maternal age, or suspicion of chromosomal abnormalities, none of which are suggested by accidental **low-dose radiation exposure**. - Radiation-induced effects are typically teratogenic rather than directly causing inheritable genetic mutations that would be detected by standard genetic testing.
Question 10: Which of the following conditions is associated with ectopia lentis?
- A. Homocystinuria (Correct Answer)
- B. Alport syndrome
- C. Lowe syndrome
- D. Sulphite oxidase deficiency
Explanation: ***Homocystinuria*** - **Ectopia lentis** (lens dislocation) is a common and characteristic ocular manifestation of homocystinuria. - The lens typically dislocates **downward and inward**, differentiating it from Marfan syndrome. *Alport syndrome* - Characterized by **glomerulonephritis**, **sensorineural hearing loss**, and ocular abnormalities. - Ocular manifestations include **anterior lenticonus** (which can be mistaken for ectopia lentis in some descriptions), posterior polymorphous corneal dystrophy, and retinal flecks, but not classic ectopia lentis. *Lowe syndrome* - Also known as oculocerebrorenal syndrome of Lowe, it primarily affects the **eyes, brain, and kidneys**. - Ocular features include **congenital cataracts** and glaucoma, but not ectopia lentis. *Sulphite oxidase deficiency* - This is a rare metabolic disorder affecting the metabolism of sulfur-containing amino acids, leading to severe neurological symptoms. - While it can manifest with **cataracts** and **lens subluxation** in some cases, ectopia lentis is more characteristically associated with homocystinuria, and the overall clinical picture of sulphite oxidase deficiency is dominated by severe neurological impairment.
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