FMGE 2023 Practice Questions

Q: A female patient complains of swelling and pain in her great toe. Her uric acid level is found to be high. A drug that reduces uric acid levels is prescribed. Which of the following enzymes should the drug inhibit?

Xanthine oxidase. ***Xanthine oxidase*** - **Xanthine oxidase** catalyzes the conversion of hypoxanthine to xanthine and xanthine to uric acid in the purine degradation pathway - **Xanthine oxidase inhibitors** (allopurinol, febuxostat) are the mainstay drugs for chronic management of hyperuricemia and gout - By inhibiting this enzyme, these drugs reduce uric acid production, lowering serum uric acid levels and preventing crystal deposition in joints - The clinical presentation of **podagra** (acute pain and swelling of the great toe) with elevated uric acid is classic for **acute gouty arthritis** *Lysyl oxidase* - Involved in cross-linking collagen and elastin in connective tissue formation - Not related to purine metabolism or uric acid synthesis - Inhibition would affect collagen strength, not uric acid levels *Homogentisate oxidase* - Enzyme in the tyrosine degradation pathway - Deficiency causes alkaptonuria (accumulation of homogentisic acid) - Not involved in purine metabolism *Urease* - Bacterial enzyme that hydrolyzes urea to ammonia and carbon dioxide - Found in bacteria like *Helicobacter pylori* and *Proteus* species - Not involved in human uric acid synthesis or metabolism

Q: A patient presented to the OPD with liver damage. The picture depicts the patient having their eyes examined. Which of the following substances is responsible for this condition?

Copper. ***Copper*** - The image displays a **Kayser-Fleischer ring**, a greenish-gold ring at the corneal limbus, which is a hallmark sign of **Wilson's disease**. This condition, combined with liver damage, points to an issue with copper metabolism. - Wilson's disease is an autosomal recessive disorder caused by a mutation in the **ATP7B gene**, leading to impaired biliary excretion and subsequent toxic accumulation of **copper** in the liver, brain, and cornea. *Glucose* - Elevated **glucose** levels, as seen in diabetes mellitus, can cause ocular complications such as **diabetic retinopathy** and **cataracts**, but not Kayser-Fleischer rings. - While diabetes can be associated with liver disease (e.g., **NAFLD**), the combination of this specific eye finding and liver damage is not characteristic of glucose-related pathology. *Galactose* - Excess **galactose** is characteristic of **galactosemia**, an inherited metabolic disorder that can cause liver failure and cirrhosis, similar to Wilson's disease. - However, the classic ocular finding in galactosemia is the formation of **"oil-droplet" cataracts**, not the Kayser-Fleischer rings shown in the image. *Mannose* - Disorders of **mannose** metabolism are typically classified as **congenital disorders of glycosylation (CDGs)**. - These rare genetic disorders present with a wide spectrum of multi-systemic symptoms, including neurological and developmental issues, but are not associated with the development of Kayser-Fleischer rings.

Q: A patient who was in excruciating pain all over his body was taken to the hospital. In recent years, he has experienced these episodes frequently. When exercising vigorously, the pain begins. Anemia was detected on blood examination along with sickled RBCs as opposed to normal biconcave ones. It was determined that he had sickle cell anemia. What substitution takes place in sickle cell anemia?

Substitution of glutamic acid by valine at the 6th position. ***Substitution of glutamic acid by valine at the 6th position***- This is the defining molecular defect in **sickle cell anemia** (HbS), resulting from a point mutation (GAG $\rightarrow$ GTG) in the $\beta$-globin gene.- The replacement of the hydrophilic amino acid **glutamic acid** by the hydrophobic amino acid **valine** at the **6th position** facilitates the polymerization of **deoxy-HbS** under low oxygen tension, causing RBC sickling.*Substitution of valine by glutamic acid at the 6th position*- This change is the **opposite** of the mutation causing HbS; HbS involves the substitution of a hydrophilic residue (Glutamic acid) with a **hydrophobic** one (Valine).- This particular reverse substitution would not lead to the formation of the **deoxy-HbS polymers** responsible for the sickling phenomenon.*Substitution of valine by glutamic acid at the 5th position*- The amino acid at the 5th position of the $\beta$-globin chain is typically **proline**, and the crucial molecular abnormality in HbS involves the **6th position**, not the 5th.- The defining mutation involves Glutamic acid being replaced by Valine, not Valine being replaced by Glutamic acid.*Substitution of glutamic acid by valine at the 5th position*- While the amino acid change (Glutamic acid $\rightarrow$ Valine) is correct for the type of substitution, the characteristic mutation of **sickle cell anemia** occurs specifically at the **6th position**.- Substitutions at different positions (like the 5th) usually result in other, distinct hemoglobin variants.

Q: Vitamin A deficiency leads to?

Xerophthalmia. ***Xerophthalmia***- **Vitamin A** (retinol) is essential for the formation of **rhodopsin**, the photopigment necessary for low-light vision, making deficiency a primary cause of **night blindness** (nyctalopia).- Deficiency leads to **keratinization** of the *corneal and conjunctival epithelium*, resulting in dryness of the eye (*xerosis*), progressing to corneal ulcers and potentially blindness (*keratomalacia*).*Beriberi*- Caused by a deficiency of **Vitamin B1** (**thiamine**), which is crucial for carbohydrate metabolism.- Symptoms include **peripheral neuropathy** (dry beriberi) or high-output cardiac failure (wet beriberi).*Pellagra*- Caused by a deficiency of **Vitamin B3** (**niacin**), or its precursor **tryptophan**.- Classically presents with the '3 Ds': **dermatitis**, **diarrhea**, and **dementia** (and eventually death).*Neuropathy*- While severe Vitamin A deficiency can cause secondary issues, primary **neuropathy** is mainly associated with deficiencies of B-vitamins like **B1** (thiamine), **B6** (pyridoxine), or **B12** (cobalamin).- *Neuropathy* is a symptom and not the specific disease term commonly linked directly and primarily to Vitamin A deficiency, which is **xerophthalmia**.

Q: A patient presented with multiple painful blisters on an erythematous base along a dermatome on the trunk, as shown in the image. What is the diagnosis? ![img-67.jpeg](img-67.jpeg)

Herpes zoster. ***Herpes zoster*** - This is the classic presentation of shingles, caused by the reactivation of the **Varicella-Zoster Virus (VZV)**, which presents as a painful, unilateral vesicular eruption in a restricted **dermatomal** distribution. - The virus remains dormant in the **dorsal root ganglia** after a primary chickenpox infection and reactivates later in life, often during periods of stress or immunosuppression. *Herpes simplex* - Herpes simplex virus (HSV) typically causes oral or genital lesions and does not usually follow a **dermatomal pattern**. - While HSV can cause skin infections, the distribution is localized to the site of inoculation rather than along a specific nerve root. *Molluscum contagiosum* - This condition is caused by a **poxvirus** and presents as flesh-colored, dome-shaped papules with central **umbilication**. - The lesions are not vesicular or painful and do not follow a dermatomal distribution. *Chicken pox* - This is the primary infection with **Varicella-Zoster Virus** and is characterized by a **generalized rash** with vesicles in different stages of healing (“dew drops on a rose petal”). - Unlike herpes zoster, the rash is widespread over the entire body and is not confined to a single dermatome.

Q: A patient presented with multiple painful blisters on an erythematous base along a dermatome on the trunk as shown in the image. What is the diagnosis?

Herpes zoster. ***Herpes zoster*** - This diagnosis is indicated by the classic presentation of a **painful, unilateral vesicular eruption** on an erythematous base, which is confined to a single **dermatome**. - It is caused by the **reactivation** of the latent **varicella-zoster virus (VZV)** from the dorsal root ganglia, which previously caused chickenpox. *Herpes simplex* - Herpes simplex virus (HSV) typically causes vesicular lesions grouped around the **orolabial** (HSV-1) or **genital** (HSV-2) regions, not in a dermatomal pattern on the trunk. - While it can cause a widespread eruption (eczema herpeticum), it does not characteristically follow a single nerve distribution like herpes zoster. *Molluscum contagiosum* - This condition presents as discrete, flesh-colored, **dome-shaped papules** with central **umbilication**, not as painful vesicles on an erythematous base. - It is caused by a **poxvirus**, and the lesions are typically scattered and not confined to a dermatome. *Chicken pox* - Chickenpox (primary VZV infection) presents as a **generalized, diffuse vesicular rash** that affects the entire body, rather than being limited to a single dermatome. - The rash appears in successive crops, resulting in lesions at **various stages of development** (papules, vesicles, and crusted lesions) simultaneously.

Q: A 45-year-old truck driver with a history of multiple sex partners presented to the dermatological department, as shown below. What is the likely diagnosis?

Secondary syphilis. ***Secondary syphilis*** - The image shows a classic **maculopapular rash** involving the **palms**, a hallmark feature of secondary syphilis, which is caused by the spirochete **Treponema pallidum**. - The patient's history of **multiple sex partners** is a significant risk factor, and other associated findings can include generalized lymphadenopathy, fever, and **condylomata lata**. *Lichen planus* - Characterized by the "6 P's": **pruritic, polygonal, planar, purple papules and plaques**, often with fine white lines on the surface known as **Wickham's striae**. - The lesions in the image lack these classic features and are not typically pruritic, distinguishing it from the presented case. *Scabies* - This is an intensely **pruritic** infestation caused by the mite **Sarcoptes scabiei**, which creates linear **burrows**, especially in the **interdigital web spaces**, wrists, and axillae. - The rash in secondary syphilis is classically non-pruritic, and the morphology is maculopapular rather than burrow-like. *Psoriasis* - Typically presents as **well-demarcated erythematous plaques** with a **silvery scale** on extensor surfaces like the elbows and knees. - While palmoplantar psoriasis occurs, it usually manifests as hyperkeratotic plaques or pustules, not the diffuse maculopapular rash seen here.

Q: Which of the following is true about p53?

It inhibits telomerase activity. ***It inhibits telomerase activity*** - **p53 transcriptionally represses hTERT** (telomerase reverse transcriptase), effectively downregulating telomerase activity as part of its tumor suppressor function. - This inhibition prevents **cellular immortalization** and contributes to p53's role as the "**guardian of the genome**" in preventing malignant transformation. *It increases telomere length in the liver* - p53 has **no tissue-specific function** to increase telomere length in any organ, including the liver. - p53 actually **opposes telomere maintenance** by inhibiting telomerase, which would shorten rather than lengthen telomeres. *It synthesizes RNA* - p53 is a **transcription factor** that regulates gene expression but does **not synthesize RNA directly**. - **RNA synthesis** is performed by **RNA polymerase enzymes**, while p53 modulates their activity at specific gene promoters. *It retains the telomerase enzyme in the nucleus* - p53 **represses telomerase activity** by downregulating hTERT expression, rather than retaining the enzyme. - Loss of p53 function in **cancer cells** allows telomerase reactivation, contributing to unlimited replicative potential.

Q: Which of the following drugs increases uric acid in urine?

Probenecid. ***Probenecid***- This drug is a **uricosuric agent** that works by inhibiting the reabsorption of urate at the **proximal convoluted tubule** of the kidney.- By blocking reabsorption, **probenecid** promotes the excretion of uric acid into the urine, thereby reducing serum uric acid levels.*Colchicine*- *Colchicine* is primarily used for the management of **acute gout flares** and works by inhibiting neutrophil migration and subsequent inflammatory responses.- It does **not** significantly alter the renal handling of uric acid; therefore, it does not increase uric acid excretion in the urine.*Febuxostat*- *Febuxostat* is a **non-purine selective inhibitor of xanthine oxidase**, an enzyme required for uric acid synthesis.- Its mechanism is to **decrease the production** of uric acid by the body, thus lowering serum levels, rather than promoting its excretion in the urine.*Allopurinol*- *Allopurinol* is a **purine analog and a xanthine oxidase inhibitor** used for the prophylactic management of chronic gout.- Like Febuxostat, it acts to **decrease the synthesis** (production) of uric acid, contrasting with uricosuric agents which increase excretion.

Question 1

A female patient complains of swelling and pain in her great toe. Her uric acid level is found to be high. A drug that reduces uric acid levels is prescribed. Which of the following enzymes should the drug inhibit?

Accepted Answer

Xanthine oxidase

Answer

Lysyl oxidase

Answer

Homogentisate oxidase

Answer

Urease

Question 2

A patient presented to the OPD with liver damage. The picture depicts the patient having their eyes examined. Which of the following substances is responsible for this condition?

Accepted Answer

Copper

Answer

Glucose

Answer

Galactose

Answer

Mannose

Question 3

A patient who was in excruciating pain all over his body was taken to the hospital. In recent years, he has experienced these episodes frequently. When exercising vigorously, the pain begins. Anemia was detected on blood examination along with sickled RBCs as opposed to normal biconcave ones. It was determined that he had sickle cell anemia. What substitution takes place in sickle cell anemia?

Accepted Answer

Substitution of glutamic acid by valine at the 6th position

Answer

Substitution of valine by glutamic acid at the 5th position

Answer

Substitution of glutamic acid by valine at the 5th position

Answer

Substitution of valine by glutamic acid at the 6th position

Question 4

Vitamin A deficiency leads to?

Accepted Answer

Xerophthalmia

Answer

Beriberi

Answer

Neuropathy

Answer

Pellagra

Question 5

A patient presented with multiple painful blisters on an erythematous base along a dermatome on the trunk, as shown in the image. What is the diagnosis? ![img-67.jpeg](img-67.jpeg)

Accepted Answer

Herpes zoster

Answer

Herpes simplex

Answer

Molluscum contagiosum

Answer

Chicken pox

Question 6

A patient presented with multiple painful blisters on an erythematous base along a dermatome on the trunk as shown in the image. What is the diagnosis?

Accepted Answer

Herpes zoster

Answer

Herpes simplex

Answer

Molluscum contagiosum

Answer

Chicken pox

Question 7

A 45-year-old truck driver with a history of multiple sex partners presented to the dermatological department, as shown below. What is the likely diagnosis?

Accepted Answer

Secondary syphilis

Answer

Lichen planus

Answer

Scabies

Answer

Psoriasis

Question 8

Which of the following is true about p53?

Accepted Answer

It inhibits telomerase activity

Answer

It retains the telomerase enzyme in the nucleus

Answer

It increases telomere length in the liver.

Answer

It synthesizes RNA

Question 9

Which of the following drugs increases uric acid in urine?

Accepted Answer

Probenecid

Answer

Allopurinol

Answer

Colchicine

Answer

Febuxostat

Question 10

The most appropriate description of the vasomotor reversal of Dale is that

Accepted Answer

A patient pretreated with phentolamine develops severe hypotension on the administration of adrenaline

Answer

Repeated administration of ephedrine decreases its effect on blood pressure

Answer

An increase in pulse pressure is produced by the intravenous administration of isoprenaline

Answer

High dose of acetylcholine after alpha blockade produces vasomotor reversal

FMGE 2023

Biochemistry

Dermatology

Pathology

Pharmacology