Biochemistry
1 questionsWhich type of mutation can act as a suppressor to restore the wild-type phenotype in organisms carrying a mutant gene?
INI-CET 2024 - Biochemistry INI-CET Practice Questions and MCQs
Question 91: Which type of mutation can act as a suppressor to restore the wild-type phenotype in organisms carrying a mutant gene?
- A. Frameshift mutation of coding gene
- B. Mutation of tRNA (Correct Answer)
- C. Deletion of mutant gene
- D. Addition of another normal gene
Explanation: ***Mutation of tRNA*** - A **tRNA suppressor mutation** can alter its anticodon, allowing it to recognize a **stop codon** (nonsense suppressor) or a missense codon, and insert an amino acid, thereby suppressing the original mutation. - This is a classic example of an **intergenic suppressor mutation** that acts at a different genetic locus from the original mutation. - These suppressors are particularly effective for **nonsense mutations** (premature stop codons) and certain missense mutations by correcting the decoding error during translation. *Frameshift mutation of coding gene* - A single frameshift mutation causes a shift in the **reading frame**, leading to a completely different protein sequence downstream and often a premature stop codon, which would worsen the phenotype. - While a **second compensating frameshift** mutation in the same gene could theoretically restore the reading frame (acting as an intragenic suppressor), this is context-dependent and less reliable than tRNA suppressors. - The question asks for mutations that "can act as a suppressor," and **tRNA mutations are the more universally recognized and reliable suppressor mechanism** in classical genetics. *Deletion of mutant gene* - **Deleting the mutant gene** removes the genetic information entirely but does not restore wild-type function; instead, it typically results in **loss of function** or complete absence of the protein. - This would lead to a **null phenotype** rather than restoration of wild-type phenotype, especially if the gene is essential. *Addition of another normal gene* - The **addition of another normal (wild-type) gene copy** provides a functional protein that can compensate for the mutant gene's deficiency. - While this can restore a wild-type phenotype, it represents **gene complementation** or gene therapy, not a true suppressor mutation that modifies the interpretation or expression of the existing mutant allele.
Internal Medicine
2 questionsWhich of the following disorders presents with repeated catalase positive infections?
Least common cause for bilateral pedal edema
INI-CET 2024 - Internal Medicine INI-CET Practice Questions and MCQs
Question 91: Which of the following disorders presents with repeated catalase positive infections?
- A. Chediak higashi syndrome
- B. SCID
- C. X linked hypogammaglobulinemia
- D. CGD (Correct Answer)
Explanation: ***CGD*** - Chronic Granulomatous Disease (CGD) is characterized by a defect in **NADPH oxidase**, preventing phagocytes from producing a **respiratory burst** to kill certain bacteria and fungi. - Patients with CGD are particularly susceptible to infections by **catalase-positive organisms** because these organisms degrade hydrogen peroxide, which CGD phagocytes rely on for killing. *Chediak higashi syndrome* - This syndrome involves defective lysosomal trafficking, leading to impaired neutrophil chemotaxis and degranulation, resulting in recurrent infections, but not specifically to **catalase-positive organisms**. - Other features include **partial albinism**, peripheral neuropathy, and normal respiratory burst. *SCID* - Severe Combined Immunodeficiency (SCID) involves a profound defect in both **T-cell and B-cell immunity**, leading to severe and recurrent infections by a wide range of pathogens, not limited to catalase-positive ones [1]. - Patients typically present in infancy with **failure to thrive**, opportunistic infections, and lack of lymphoid tissue [1]. *X linked hypogammaglobulinemia* - Also known as **Bruton's agammaglobulinemia**, this disorder involves a defect in B-cell maturation, leading to the absence of antibodies and recurrent bacterial infections [1]. - The infections are typically with **encapsulated bacteria** and are not specifically linked to catalase-positive organisms [1].
Question 92: Least common cause for bilateral pedal edema
- A. CKD
- B. Chronic vascular insufficiency (Correct Answer)
- C. CLD
- D. HF with reduced ejection fraction
Explanation: ***Chronic vascular insufficiency*** - While chronic venous insufficiency is a common cause of bilateral pedal edema, **arterial insufficiency** (a type of chronic vascular insufficiency) is a much less common cause of pure edema and is more often associated with **ischemic pain**, **ulcers**, and **skin atrophy** [1]. - **Arterial insufficiency** primarily causes limb ischemia rather than significant edema, differentiating it from situations where fluid retention is the primary issue [2]. *CKD* - **Chronic kidney disease (CKD)** leads to impaired fluid and sodium excretion, causing generalized fluid overload. - This fluid overload commonly manifests as **bilateral pedal edema** due to gravity-dependent fluid accumulation. *CLD* - **Chronic liver disease (CLD)**, particularly cirrhosis, results in **portal hypertension** and decreased hepatic synthesis of **albumin**. - This leads to reduced oncotic pressure and increased hydrostatic pressure, driving fluid into the extravascular space, often causing **ascites** and **bilateral pedal edema**. *HF with reduced ejection fraction* - **Heart failure with reduced ejection fraction (HFrEF)** impairs the heart's ability to pump blood effectively, leading to fluid backup in the venous system [2]. - This increased hydrostatic pressure in the peripheral capillaries directly causes **bilateral pedal edema** as fluid extravasates into the interstitial space [2].
Obstetrics and Gynecology
1 questionsA 32-year-old female at 36 weeks of pregnancy presents with BP 170/100 mmHg, visual disturbances, headache, urine protein 3+. What will be the next step?
INI-CET 2024 - Obstetrics and Gynecology INI-CET Practice Questions and MCQs
Question 91: A 32-year-old female at 36 weeks of pregnancy presents with BP 170/100 mmHg, visual disturbances, headache, urine protein 3+. What will be the next step?
- A. IV labetalol and delivery at 37 weeks
- B. IV labetalol, dexamethasone, and immediate termination of pregnancy
- C. IV labetalol, dexamethasone, and conservative management
- D. IV labetalol, magnesium sulfate (MgSO4), expedite delivery (Correct Answer)
Explanation: ***IV labetalol, magnesium sulfate (MgSO4), expedite delivery*** - The patient presents with **severe preeclampsia** (BP > 160/110 mmHg, visual disturbances, headache, proteinuria) at 36 weeks, requiring **antihypertensive therapy** (labetalol) and seizure prophylaxis (**magnesium sulfate**). - Given the severe features and gestational age, **expedited delivery** is indicated to prevent maternal and fetal complications, as expectant management beyond severe preeclampsia at this stage offers minimal benefit and increased risk. *IV labetalol and delivery at 37 weeks* - While IV labetalol is appropriate for **blood pressure control**, delaying delivery to 37 weeks might not be optimal given the **severe features of preeclampsia** at 36 weeks, increasing risks for both mother and fetus. - The plan is incomplete without mentioning **seizure prophylaxis** with magnesium sulfate, which is crucial for severe preeclampsia. *IV labetalol, dexamethasone, and immediate termination of pregnancy* - **Dexamethasone** is used for **fetal lung maturity** in preterm deliveries and is not indicated for immediate termination unless the fetus is preterm and lung maturity is a concern. At 36 weeks, lung maturity is usually established. - While immediate termination might be considered, the phrase "immediate termination" implies C-section without considering vaginal delivery and overlooks the need for **seizure prophylaxis**. *IV labetalol, dexamethasone, and conservative management* - **Dexamethasone** is not a primary treatment for severe preeclampsia itself but rather for **fetal lung maturation** in preterm deliveries, which is less critical at 36 weeks. - **Conservative management** is generally inappropriate for **severe preeclampsia** at 36 weeks, as it increases maternal and fetal risk; delivery is the definitive treatment.
Pathology
2 questionsA patient presents with neck swelling causing compression of the trachea and esophagus. Histopathological assessment reveals cell nests and pink extracellular amyloid stroma. What is the cell of origin of the tumor associated with these findings?
Molecular genetic testing is used to detect all of the following except?
INI-CET 2024 - Pathology INI-CET Practice Questions and MCQs
Question 91: A patient presents with neck swelling causing compression of the trachea and esophagus. Histopathological assessment reveals cell nests and pink extracellular amyloid stroma. What is the cell of origin of the tumor associated with these findings?
- A. Parafollicular C cells (Correct Answer)
- B. Hurthle cells
- C. Follicular cells
- D. Chief cells
Explanation: ***Parafollicular C cells*** - The presence of **cell nests** and **pink extracellular amyloid stroma** are classic histopathological findings for **medullary thyroid carcinoma (MTC)**, which originates from the parafollicular C cells [2], [3]. - Parafollicular C cells are responsible for producing **calcitonin**, and the amyloid in these tumors is derived from calcitonin [3]. - MTC accounts for 5-10% of thyroid cancers and can be sporadic or familial (associated with MEN 2A and 2B syndromes) [1], [4]. *Chief cells* - Chief cells are **parathyroid gland cells** that produce parathyroid hormone (PTH), not thyroid tumor cells. - While parathyroid adenomas can cause neck masses, they do not produce the characteristic amyloid stroma seen in medullary carcinoma. *Hürthle cells* - Hürthle cells (also known as Askanazy cells or oncocytes) are a type of **follicular cell** characterized by abundant **eosinophilic, granular cytoplasm** due to numerous mitochondria. - While they can form tumors (**Hürthle cell adenoma or carcinoma**), these tumors do not typically feature cell nests or amyloid stroma. *Follicular cells* - Follicular cells are the most common cell type in the thyroid and are the origin of most thyroid cancers, including **papillary** and **follicular carcinomas** [4]. - These tumors generally do not present with the characteristic **amyloid stroma** and cell nests described in the question. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1102-1103. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 430-431. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-429. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 429-430.
Question 92: Molecular genetic testing is used to detect all of the following except?
- A. Deletion
- B. Translocation (Correct Answer)
- C. Amplification
- D. Point mutation
Explanation: ***Translocation*** - **Translocations** are chromosomal rearrangements that were historically detected primarily by **cytogenetic methods** (karyotyping, conventional FISH), rather than by traditional molecular genetic testing methods focused on DNA sequencing [3]. - While modern molecular techniques like **RT-PCR for fusion transcripts** (e.g., BCR-ABL), **NGS-based fusion detection**, and **targeted breakpoint sequencing** can now detect translocations, the classic distinction is that translocations involve large-scale structural chromosomal changes better visualized by cytogenetics [2], [3]. - In the traditional classification, molecular genetic testing referred primarily to **sequence-based methods** (PCR, Sanger sequencing) that detect smaller-scale DNA changes rather than gross chromosomal rearrangements. *Deletion* - **Deletions** are readily detected by molecular genetic testing using PCR, Sanger sequencing, MLPA (Multiplex Ligation-dependent Probe Amplification), and NGS [5]. - These techniques identify missing DNA sequences by analyzing changes in fragment size, read depth, or absence of expected amplification products [2], [5]. *Amplification* - **Amplification** (increased gene copy number) is detected by molecular methods including **quantitative PCR (qPCR)**, **digital PCR**, and **NGS-based copy number analysis** [4]. - These techniques quantify gene copy numbers to identify amplifications like HER2 amplification in breast cancer. *Point mutation* - **Point mutations** are the primary target of classic molecular genetic testing [1]. - Detected by **Sanger sequencing**, **allele-specific PCR**, **NGS panels**, and other sequence-based methods that identify single nucleotide changes in DNA [1], [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, p. 185. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 185-186. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 342-343. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 344. [5] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 183-184.
Pharmacology
2 questionsIn which of the following conditions are cannabinoids not commonly used for treatment?
Drug of choice for Enterococcus infection in a patient allergic to penicillin?
INI-CET 2024 - Pharmacology INI-CET Practice Questions and MCQs
Question 91: In which of the following conditions are cannabinoids not commonly used for treatment?
- A. Tuberous sclerosis
- B. Rett syndrome (Correct Answer)
- C. Lennox-Gastaut Syndrome
- D. Dravet syndrome
Explanation: ***Rett syndrome*** - Cannabinoids are **NOT commonly used** as an established treatment for **Rett syndrome** - While some research is exploring their potential therapeutic role, they remain **investigational only** and lack FDA approval for this indication - Current management focuses on symptomatic treatment including physical therapy, anti-epileptics for seizures, and supportive care - Unlike the other conditions listed, there is **no established cannabinoid therapy** for Rett syndrome in clinical practice *Dravet syndrome* - **Cannabidiol (CBD/Epidiolex)** is **FDA-approved** and commonly used for treatment of seizures associated with **Dravet syndrome** - Demonstrates significant efficacy in reducing seizure frequency in this severe infantile-onset epilepsy - Represents a major therapeutic advance for this treatment-resistant condition *Tuberous sclerosis* - **Cannabidiol (CBD/Epidiolex)** received **FDA approval in 2018** for treatment of seizures associated with **tuberous sclerosis complex (TSC)** - Commonly used as an adjunctive therapy alongside other treatments like vigabatrin or mTOR inhibitors (everolimus) - Clinical trials demonstrated significant reduction in seizure frequency in TSC patients *Lennox-Gastaut Syndrome* - **Cannabidiol (CBD/Epidiolex)** is **FDA-approved** for seizures associated with **Lennox-Gastaut Syndrome (LGS)** - Commonly used in this severe epileptic encephalopathy characterized by multiple seizure types and developmental delay - Effective in reducing seizure burden in patients refractory to traditional anti-epileptic drugs
Question 92: Drug of choice for Enterococcus infection in a patient allergic to penicillin?
- A. Streptomycin
- B. Cephalosporin
- C. Vancomycin (Correct Answer)
- D. Rifampicin
Explanation: ***Vancomycin*** - **Vancomycin** is a glycopeptide antibiotic that is effective against **Gram-positive bacteria**, including *Enterococcus*, especially in patients with a **penicillin allergy**. - It inhibits **cell wall synthesis** by binding to the D-Ala-D-Ala terminus of peptidoglycan precursors, a different mechanism from penicillins. *Streptomycin* - **Streptomycin** is an aminoglycoside that inhibits **protein synthesis** and is primarily used in **combination therapy** for serious *Enterococcal* infections, but typically alongside a cell-wall active agent (like penicillin or vancomycin) for synergistic killing in endocarditis or other severe infections. - It is not usually recommended as a **monotherapy** for *Enterococcus*, especially in the context of penicillin allergy, as it doesn't provide bactericidal activity on its own against all enterococcal strains. *Cephalosporin* - **Cephalosporins** are **not active** against *Enterococcus spp.* as these bacteria intrinsically lack the **penicillin-binding proteins (PBPs)** that cephalosporins target effectively. - This **intrinsic resistance** makes cephalosporins an inappropriate choice for treating *Enterococcal* infections, regardless of penicillin allergy status. *Rifampicin* - **Rifampicin** is an antibiotic primarily used for **Mycobacterial infections** (e.g., tuberculosis) and some **Staphylococcal infections**, often in combination to prevent resistance. - It has **poor activity** against *Enterococcus* and is not a recommended treatment for *Enterococcal* infections.
Psychiatry
2 questionsmhGAP program includes all of the following disorders except?
Which of the following is not associated with Korsakoff psychosis?
INI-CET 2024 - Psychiatry INI-CET Practice Questions and MCQs
Question 91: mhGAP program includes all of the following disorders except?
- A. Schizophrenia
- B. Depression
- C. Childhood mental disorder
- D. Personality Disorders (Correct Answer)
Explanation: ***Personality Disorders*** - The **mhGAP program** (Mental Health Gap Action Programme) focuses on scaling up services for common, severe mental, neurological, and substance use disorders in low- and middle-income countries. - **Personality disorders** are generally not included in the core conditions addressed by the mhGAP program due to their complex and chronic nature, requiring specialized and long-term management that may be beyond the scope of primary care settings targeted by mhGAP. *Schizophrenia* - **Schizophrenia** is one of the priority conditions addressed by the mhGAP program, recognizing its severity and significant impact on individuals and communities. - The program provides guidelines for the recognition, management, and long-term care of schizophrenia at the primary healthcare level. *Depression* - **Depression** is a core focus of the mhGAP program, given its high prevalence and treatability in primary care settings. - mhGAP provides clear guidelines for the identification, basic management, and follow-up of individuals with depression. *Childhood mental disorder* - **Childhood mental disorders**, such as conduct disorder, attention-deficit/hyperactivity disorder (ADHD), and developmental disabilities, are also included as priority conditions within the mhGAP program. - The program aims to improve the detection and basic management of these conditions in children and adolescents, promoting early intervention.
Question 92: Which of the following is not associated with Korsakoff psychosis?
- A. Ophthalmoplegia (Correct Answer)
- B. Amnesia
- C. Confabulation
- D. Polyneuropathy
Explanation: ***Ophthalmoplegia*** - **Ophthalmoplegia** is a key feature of **Wernicke encephalopathy**, the acute phase preceding Korsakoff psychosis, but is not directly a symptom of Korsakoff psychosis itself. - While both conditions are linked to thiamine deficiency, **Korsakoff psychosis** primarily manifests as chronic memory deficits. *Amnesia* - **Anterograde amnesia** (inability to form new memories) and **retrograde amnesia** (loss of past memories) are defining characteristics of Korsakoff psychosis. - This severe memory impairment is a result of damage to areas like the **mammillary bodies** and **thalamus**. *Confabulation* - **Confabulation**, the fabrication of distorted or misinterpreted memories without an intention to deceive, is a common symptom in patients with Korsakoff psychosis. - This occurs as patients attempt to fill in gaps in their memory loss, often believing their own stories. *Polyneuropathy* - **Polyneuropathy**, nerve damage affecting multiple peripheral nerves, causing symptoms like pain, numbness, and muscle weakness, is associated with chronic **alcoholism** and **thiamine deficiency**. - While not a direct psychological symptom, it is frequently seen in the same patient population that develops Korsakoff psychosis due to shared etiology.