Teratology — MCQs
Not true about thalidomide:
Which of the following causes teratogenicity?
Seal like limbs i.e. phocomelia is a specific side effect of -
Cantrell pentalogy include all except
Which of the following STDs causes fetal abnormality?
Which of the following is the necessary pre-operative investigation which has to be done in a patient with Down's syndrome posted for surgery?
Which malformation is associated with mutations in the HOX gene?
What maternal condition is commonly associated with congenital heart defects in the fetus?
18 weeks pregnant female presents with no high risk of NTD and low risk of trisomy 21 on quad test. What is the most appropriate next step in management?
What are the typical contents of a meningocele sac?
Teratology Indian Medical PG Practice Questions and MCQs
Question 1: Not true about thalidomide:
- A. Causes phocomelia
- B. Still has restricted clinical use
- C. Not tested in pregnant animals before introduction
- D. Has no antiangiogenesis action against tumour (Correct Answer)
Explanation: ***Has no antiangiogenesis action against tumour*** - Thalidomide is known to possess **anti-angiogenic properties**, meaning it inhibits the formation of new blood vessels, which is crucial for tumour growth. This makes the statement "has no antiangiogenesis action against tumour" incorrect. - Its anti-angiogenic effects are one of the mechanisms proposed for its use in certain cancers, such as **multiple myeloma**. *Causes phocomelia* - **Phocomelia**, a severe birth defect characterized by malformed or absent limbs, is the most infamous **teratogenic effect** of thalidomide. - This adverse effect led to its withdrawal from the market in the early 1960s. *Still has restricted clinical use* - Despite its teratogenic risks, thalidomide has been reintroduced with strict regulations due to its unique immunomodulatory and anti-inflammatory properties. - It is currently used in the treatment of conditions like **multiple myeloma**, **erythema nodosum leprosum**, and certain autoimmune diseases. *Not tested in pregnant animals before introduction* - A significant reason for the thalidomide tragedy was the **lack of robust teratogenicity testing** in pregnant animals before its widespread introduction to the market. - If such testing had been adequately conducted, its severe teratogenic effects might have been identified earlier, preventing widespread harm.
Question 2: Which of the following causes teratogenicity?
- A. Vitamin E
- B. Vitamin D
- C. Vitamin A (Correct Answer)
- D. Vitamin C
Explanation: ***Vitamin A*** - Excessive intake of **Vitamin A (retinoids)**, particularly during early pregnancy, is a known cause of **teratogenicity**. - It can lead to various birth defects, including **craniofacial abnormalities**, **cardiac defects**, and **central nervous system malformations**. *Vitamin E* - **Vitamin E** is generally considered safe during pregnancy and has no known teratogenic effects at recommended dosages. - It functions as an **antioxidant** and is important for cell protection. *Vitamin D* - While **Vitamin D** is essential for proper fetal development, excessive intake is not typically associated with teratogenicity but can cause **hypercalcemia** in the mother and fetus. - Mild to moderate supplementation is often recommended during pregnancy for bone health. *Vitamin C* - **Vitamin C** is a water-soluble vitamin and is not considered teratogenic, even at higher doses, as excess amounts are readily excreted. - It plays a crucial role in **collagen synthesis** and immune function during pregnancy.
Question 3: Seal like limbs i.e. phocomelia is a specific side effect of -
- A. Doxorubicin
- B. Thalidomide (Correct Answer)
- C. Cyclophosphamide
- D. Terazosin
Explanation: ***Thalidomide*** - **Phocomelia**, characterized by severely shortened or absent limbs resembling those of a seal, is a classic and well-documented **teratogenic effect** of thalidomide. - This drug, when taken during early pregnancy (especially between weeks 4 and 8), disrupts limb bud development. *Doxorubicin* - **Doxorubicin** is an **anthracycline antibiotic** used in cancer chemotherapy, known for its significant **cardiotoxicity**, leading to dilated cardiomyopathy. - While it has various side effects, **phocomelia** is not a reported teratogenic effect of doxorubicin. *Cyclophosphamide* - **Cyclophosphamide** is an **alkylating agent** used in chemotherapy and immunosuppression, with notable side effects including **hemorrhagic cystitis** and **myelosuppression**. - Although it is a teratogen and can cause various fetal malformations, it is not specifically associated with **phocomelia**. *Terazosin* - **Terazosin** is an **alpha-1 blocker** primarily used to treat hypertension and benign prostatic hyperplasia (BPH). - Its main side effects include **orthostatic hypotension** and dizziness; it is not known to be teratogenic or associated with **phocomelia**.
Question 4: Cantrell pentalogy include all except
- A. ASD
- B. Trisomy 21 (Correct Answer)
- C. VSD
- D. TOF
Explanation: ***Trisomy 21*** - **Cantrell's pentalogy** is a rare congenital condition involving defects of the **diaphragm**, **abdominal wall**, **pericardium**, **sternum**, and **heart**. - **Trisomy 21 (Down syndrome)** is a chromosomal abnormality characterized by distinct facial features, intellectual disability, and various congenital anomalies, but it is not a component of Cantrell's pentalogy. *ASD* - An **atrial septal defect (ASD)** is a common cardiac anomaly found in Cantrell's pentalogy, resulting from improper development of the heart. - The cardiac defect is one of the five primary components of **Cantrell's pentalogy**. *VSD* - A **ventricular septal defect (VSD)** is another frequent cardiac defect associated with Cantrell's pentalogy. - This defect involves a hole in the wall separating the two lower chambers of the heart and is a key feature of the **cardiac malformation component**. *TOF* - **Tetralogy of Fallot (TOF)** is a complex congenital heart defect often seen in cases of Cantrell's pentalogy. - It comprises four specific heart anomalies and contributes to the significant **cardiovascular malformations** in this syndrome.
Question 5: Which of the following STDs causes fetal abnormality?
- A. Syphilis (Correct Answer)
- B. Herpes
- C. Gonorrhea
- D. Hepatitis B
Explanation: ***Syphilis*** - **Congenital syphilis**, resulting from maternal infection, can lead to severe fetal abnormalities such as **bone deformities**, **saddle nose**, **Hutchinson's teeth**, and **neurological problems**. - It can also cause stillbirth, prematurity, or hydrops fetalis, emphasizing the importance of early detection and treatment during pregnancy. *Herpes* - While **neonatal herpes** can be life-threatening and cause neurological damage, it is typically acquired during passage through the birth canal and does not cause **fetal abnormalities** during gestation. - Herpes simplex virus primarily causes localized lesions and systemic infection in the neonate, not developmental defects. *Gonorrhea* - Gonorrhea primarily causes **ophthalmia neonatorum** (conjunctivitis) in newborns through exposure during birth, which can lead to blindness if untreated. - It does not typically cause **fetal abnormalities** or congenital defects through transplacental transmission. *Hepatitis B* - Hepatitis B can be transmitted to the fetus during birth, leading to **chronic hepatitis B infection** in the infant. - Although it causes a chronic disease, it does not typically result in **fetal abnormalities** or congenital malformations.
Question 6: Which of the following is the necessary pre-operative investigation which has to be done in a patient with Down's syndrome posted for surgery?
- A. Echocardiography to assess congenital heart defects (Correct Answer)
- B. Cervical spine X-Ray to evaluate atlantoaxial instability
- C. Abdominal ultrasound to detect gastrointestinal anomalies
- D. Brain CT scan to identify structural abnormalities
Explanation: ***Echocardiography to assess congenital heart defects*** - Patients with **Down syndrome (Trisomy 21)** have a high incidence of congenital heart defects, most commonly **atrioventricular septal defects**, which require evaluation prior to surgery due to their anesthetic and surgical implications. - Pre-surgical echocardiography is crucial to identify and characterize these defects, allowing for appropriate perioperative management and optimization of cardiac function. *Cervical spine X-Ray to evaluate atlantoaxial instability* - While **atlantoaxial instability** is a known concern in Down syndrome, particularly important for procedures involving neck manipulation, it is not universally necessary for *every* surgical patient. - Cervical spine imaging is typically reserved for elective procedures where neck manipulation is anticipated or if there are clinical signs suggestive of myelopathy. *Abdominal ultrasound to detect gastrointestinal anomalies* - Gastrointestinal anomalies like **duodenal atresia** or **Hirschsprung disease** are more prevalent in Down syndrome but are usually identified and treated in infancy or childhood due to symptomatic presentation. - Unless there are specific clinical symptoms or a history of unaddressed GI issues, a routine preoperative abdominal ultrasound is generally not indicated. *Brain CT scan to identify structural abnormalities* - Individuals with Down syndrome often have developmental brain differences, but a routine preoperative brain CT scan is not standard practice unless there are neurological symptoms or a history of conditions like seizures or hydrocephalus requiring investigation. - It would not be considered a necessary **pre-operative investigation** for general surgical fitness in the absence of specific indications.
Question 7: Which malformation is associated with mutations in the HOX gene?
- A. Polysyndactyly (Correct Answer)
- B. Holoprosencephaly
- C. Mayer Rokitansky syndrome
- D. Gorlin syndrome
Explanation: ***Polysyndactyly*** - The **HOX gene** plays a critical role in limb development and is associated with the malformation of **polysyndactyly**, which is characterized by extra fingers or toes [1]. - This condition is due to the disruption of the normal **patterning** during limb formation, directly involving the action of HOX genes [1]. *Gorlin syndrome* - Gorlin syndrome is primarily caused by mutations in the **PTCH1 gene**, linked to **basal cell carcinoma** and other abnormalities. - It does not involve HOX gene mutations, hence is **not** related to limb malformations. *Holoprosencephaly* - Holoprosencephaly is a developmental condition often linked to **chromosomal anomalies** and abnormal embryonic development, **not specifically** HOX gene mutations. - It refers to the incomplete separation of the forebrain, distinct from the **limb malformations** associated with HOX genes. *Mayer Rokitansky syndrome* - Mayer-Rokitansky syndrome involves **agenesis** or **hypoplasia** of the uterus and upper two-thirds of the vagina, which is due to other genetic factors. - This condition is not related to the functions of the **HOX genes** in limb or skeletal development. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1186.
Question 8: What maternal condition is commonly associated with congenital heart defects in the fetus?
- A. ACE inhibitor
- B. GDM
- C. Pregestational DM (Correct Answer)
- D. Valproate
Explanation: ***Pregestational DM*** - **Pre-existing diabetes** in the mother is a significant risk factor for various **congenital anomalies**, including **congenital heart defects**, due to suboptimal glycemic control during early embryogenesis. - Poorly controlled **maternal hyperglycemia** leads to increased oxidative stress and altered cellular metabolism in the developing fetus, impacting cardiovascular development. *ACE inhibitor* - **ACE inhibitors** are teratogenic, primarily causing **renal dysfunction** (e.g., renal tubular dysplasia, oligohydramnios, anuria) and **fetal growth restriction**, especially when used in the second and third trimesters. - While they can have adverse fetal effects, their association with **congenital heart defects** is less pronounced compared to other teratogenic exposures. *GDM* - **Gestational diabetes mellitus (GDM)** typically develops in the second or third trimester when major organogenesis is complete, making its association with **structural congenital anomalies**, including heart defects, significantly lower than pregestational diabetes. - GDM is more commonly associated with fetal **macrosomia**, **hypoglycemia**, and respiratory distress syndrome at birth. *Valproate* - **Valproate** is a known teratogen associated with a specific pattern of anomalies, most notably **neural tube defects** (e.g., spina bifida), and facial dysmorphisms. - While it can be associated with an increased risk of some congenital heart defects, its primary and most significant fetal risk is **neural tube defects**.
Question 9: 18 weeks pregnant female presents with no high risk of NTD and low risk of trisomy 21 on quad test. What is the most appropriate next step in management?
- A. Repeat non-invasive screening test.
- B. Perform invasive diagnostic testing.
- C. Perform amniotic fluid analysis.
- D. Perform a detailed fetal ultrasound. (Correct Answer)
Explanation: ***Perform a detailed fetal ultrasound.*** - A **detailed fetal ultrasound** (often referred to as an **anatomy scan**) at around 18-22 weeks is a standard component of prenatal care for all pregnant women, regardless of screening test results. - This ultrasound evaluates fetal anatomy for structural anomalies, assesses fetal growth, and confirms gestational age, providing crucial information even with low-risk screening. *Repeat non-invasive screening test.* - Repeating a non-invasive screening test (like another quad screen or NIPT) is generally **not indicated** when initial results show a low risk and there are no other clinical concerns. - Such tests are primarily for screening purposes, and a second low-risk result would offer little additional actionable information, as their positive predictive value is low. *Perform invasive diagnostic testing.* - **Invasive diagnostic testing**, such as **amniocentesis** or **chorionic villus sampling (CVS)**, carries a risk of miscarriage and is reserved for situations with a high risk of chromosomal abnormalities or genetic conditions. - Given the low-risk quad screen results for trisomy 21 and no high risk for NTDs, invasive testing is **not warranted** at this stage. *Perform amniotic fluid analysis.* - **Amniotic fluid analysis** is part of an amniocentesis, an **invasive diagnostic procedure** designed to detect chromosomal abnormalities or genetic disorders. - This procedure is typically reserved for cases where screening tests indicate a high risk or there is a clinical suspicion of a genetic condition; it's **not a routine step** after a low-risk quad screen.
Question 10: What are the typical contents of a meningocele sac?
- A. Spinal cord
- B. Meninges and CSF (Correct Answer)
- C. Dura mater
- D. Cauda equina
Explanation: ***Meninges and CSF*** - A meningocele is a neural tube defect characterized by herniation of the **meninges (all three layers: dura mater, arachnoid mater, and pia mater) and cerebrospinal fluid (CSF)** through a bony defect in the skull or vertebral column. - The sac contains meninges and CSF but **does NOT contain neural tissue** (spinal cord or nerve roots), which distinguishes it from myelomeningocele. - This is typically covered by skin or a thin membrane. *Dura mater* - While the dura mater is present as the outermost layer forming part of the sac wall, it is only **one component** of the meninges. - The complete answer must include all three meningeal layers (dura, arachnoid, pia) **plus CSF**, not just the dura alone. - Stating only "dura mater" is incomplete and does not accurately describe the typical contents of a meningocele. *Spinal cord* - The presence of **spinal cord tissue** within the herniated sac indicates a more severe defect called **myelomeningocele** (or meningomyelocele). - A simple meningocele by definition does **not** contain neural tissue. *Cauda equina* - The **cauda equina** consists of spinal nerve roots below the level of L1-L2. - Its presence within the herniated sac would indicate a **myelomeningocele**, not a meningocele. - Meningocele contains only meninges and CSF, with no neural elements.
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