Tyrosinemia MCQs With Answer

Tyrosinemia MCQs With Answer offers B. Pharm students a concise, high-yield review of tyrosine metabolism disorders, clinical presentations, diagnostics, and pharmacologic management. This SEO-focused introduction covers key concepts such as types of tyrosinemia, enzyme defects (FAH, TAT, HPD), diagnostic markers like succinylacetone, and first-line therapy with nitisinone (NTBC). Emphasis on newborn screening, dietary management, monitoring parameters, and complications like hepatic failure and hepatocellular carcinoma makes it ideal for pharmacy exam preparation and clinical practice. Each question is crafted to strengthen understanding of biochemical mechanisms, lab interpretation, and therapeutic counseling. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the inheritance pattern of most forms of tyrosinemia?

• Autosomal dominant
• X-linked recessive
• Autosomal recessive
• Mitochondrial inheritance

Correct Answer: Autosomal recessive

Q2. Deficiency of which enzyme causes Tyrosinemia Type I?

• Tyrosine aminotransferase (TAT)
• Fumarylacetoacetate hydrolase (FAH)
• 4-hydroxyphenylpyruvate dioxygenase (HPD)
• Homogentisate 1,2-dioxygenase

Correct Answer: Fumarylacetoacetate hydrolase (FAH)

Q3. Which biochemical marker is most specific for diagnosing Tyrosinemia Type I in newborn screening?

• Elevated plasma tyrosine
• Elevated succinylacetone in dried blood spot
• Increased phenylalanine
• Low methionine

Correct Answer: Elevated succinylacetone in dried blood spot

Q4. Nitisinone (NTBC) treats Tyrosinemia Type I by inhibiting which enzyme?

• Fumarylacetoacetate hydrolase (FAH)
• Tyrosine aminotransferase (TAT)
• 4-hydroxyphenylpyruvate dioxygenase (HPPD/HPD)
• Phenylalanine hydroxylase

Correct Answer: 4-hydroxyphenylpyruvate dioxygenase (HPPD/HPD)

Q5. The accumulation of which toxic metabolite contributes to porphyria-like neurologic crises in Tyrosinemia Type I?

• Tyrosine
• Succinylacetone
• Fumarate
• Homogentisic acid

Correct Answer: Succinylacetone

Q6. Which clinical feature is most characteristic of Tyrosinemia Type II?

• Progressive hepatic failure in infancy
• Painful hyperkeratotic lesions on palms and soles with corneal ulcers
• Renal tubular dysfunction leading to Fanconi syndrome
• Dark urine on standing due to homogentisic acid

Correct Answer: Painful hyperkeratotic lesions on palms and soles with corneal ulcers

Q7. Which laboratory test is most useful to monitor therapeutic response to NTBC in Tyrosinemia Type I?

• Plasma phenylalanine concentration
• Serum bilirubin
• Plasma succinylacetone and tyrosine levels
• Urinary ketones

Correct Answer: Plasma succinylacetone and tyrosine levels

Q8. The primary biochemical goal of dietary management in tyrosinemia is to:

• Eliminate all amino acids from the diet
• Reduce intake of tyrosine and phenylalanine to lower toxic metabolites
• Increase methionine to support liver function
• Provide high-protein supplements to correct malnutrition

Correct Answer: Reduce intake of tyrosine and phenylalanine to lower toxic metabolites

Q9. Which tyrosinemia type is caused by deficiency of tyrosine aminotransferase (TAT)?

• Type I
• Type II
• Type III
• Type IV

Correct Answer: Type II

Q10. Which complication has a markedly increased risk in untreated Tyrosinemia Type I?

• Osteoporosis only
• Hepatocellular carcinoma
• Cerebral palsy
• Type 1 diabetes mellitus

Correct Answer: Hepatocellular carcinoma

Q11. Succinylacetone inhibits which enzyme in heme biosynthesis leading to porphyria-like symptoms?

• Porphobilinogen deaminase
• Aminolevulinic acid dehydratase (ALAD)
• Ferrochelatase
• Coproporphyrinogen oxidase

Correct Answer: Aminolevulinic acid dehydratase (ALAD)

Q12. Which diagnostic technique is commonly used to detect succinylacetone in urine or blood?

• Enzyme-linked immunosorbent assay (ELISA)
• Gas chromatography–mass spectrometry (GC-MS)
• Western blot
• Complete blood count

Correct Answer: Gas chromatography–mass spectrometry (GC-MS)

Q13. What is the immediate pharmacologic effect of inhibiting HPD with NTBC in the tyrosine degradation pathway?

• Increase formation of fumarylacetoacetate
• Decrease production of downstream toxic metabolites including succinylacetone
• Stimulate FAH activity
• Increase conversion of tyrosine to homogentisic acid

Correct Answer: Decrease production of downstream toxic metabolites including succinylacetone

Q14. Which clinical sign is common in Tyrosinemia Type I due to renal involvement?

• Nephrolithiasis without tubular dysfunction
• Proximal renal tubular dysfunction (Fanconi syndrome) leading to rickets
• Isolated glomerulonephritis with hematuria
• Pigment nephropathy only

Correct Answer: Proximal renal tubular dysfunction (Fanconi syndrome) leading to rickets

Q15. In a patient on NTBC therapy, which adverse effect related to elevated tyrosine should pharmacists counsel about?

• Cardiac arrhythmias
• Ocular surface problems including corneal deposits and keratitis
• Severe hypoglycemia
• Hyperkalemia

Correct Answer: Ocular surface problems including corneal deposits and keratitis

Q16. Which of the following is the best long-term surveillance for hepatic complications in Tyrosinemia Type I?

• Periodic abdominal ultrasound and AFP monitoring
• Only annual liver function tests
• Routine chest X-ray
• Cerebral MRI

Correct Answer: Periodic abdominal ultrasound and AFP monitoring

Q17. Which gene is mutated in Tyrosinemia Type I?

• PAH (phenylalanine hydroxylase)
• FAH (fumarylacetoacetate hydrolase)
• HPD (4-hydroxyphenylpyruvate dioxygenase)
• TAT (tyrosine aminotransferase)

Correct Answer: FAH (fumarylacetoacetate hydrolase)

Q18. For B. Pharm students, which counseling point is essential when dispensing NTBC to caregivers?

• NTBC cures the genetic defect permanently
• NTBC must be taken as prescribed and dietary tyrosine/phenylalanine restriction remains necessary
• NTBC can be stopped once symptoms improve
• No monitoring is required during therapy

Correct Answer: NTBC must be taken as prescribed and dietary tyrosine/phenylalanine restriction remains necessary

Q19. Tyrosinemia Type III is due to deficiency of which enzyme?

• Tyrosine aminotransferase (TAT)
• Homogentisate 1,2-dioxygenase
• 4-hydroxyphenylpyruvate dioxygenase (HPD)
• Fumarylacetoacetate hydrolase (FAH)

Correct Answer: 4-hydroxyphenylpyruvate dioxygenase (HPD)

Q20. Which statement about newborn screening for tyrosinemia is true?

• Plasma tyrosine measurement alone is sufficient and specific
• Succinylacetone measurement improves specificity for Type I detection
• Screening is unnecessary because clinical features are always obvious at birth
• Urinalysis alone detects all types reliably

Correct Answer: Succinylacetone measurement improves specificity for Type I detection

Q21. Which metabolic consequence directly results from FAH deficiency?

• Accumulation of homogentisic acid
• Accumulation of fumarylacetoacetate and succinylacetone
• Excess conversion of tyrosine to catecholamines
• Depletion of phenylalanine

Correct Answer: Accumulation of fumarylacetoacetate and succinylacetone

Q22. Which pharmacologic property of NTBC is most relevant to its oral dosing regimen?

• It is highly unstable in the GI tract and must be injected
• It has good oral bioavailability and is formulated for oral administration
• It is rapidly degraded by plasma esterases
• It accumulates only in the central nervous system

Correct Answer: It has good oral bioavailability and is formulated for oral administration

Q23. Which of the following is NOT a typical manifestation of Tyrosinemia Type I in infants?

• Jaundice and hepatomegaly
• Failure to thrive
• Progressive neurological degeneration due to hyperammonemia
• Renal tubular dysfunction

Correct Answer: Progressive neurological degeneration due to hyperammonemia

Q24. Which statement best explains why NTBC can cause elevated plasma tyrosine?

• NTBC stimulates tyrosine synthesis in the liver
• NTBC blocks a downstream enzyme (HPD), causing upstream accumulation of tyrosine
• NTBC inhibits amino acid absorption leading to hyperaminoacidemia
• NTBC increases renal reabsorption of tyrosine

Correct Answer: NTBC blocks a downstream enzyme (HPD), causing upstream accumulation of tyrosine

Q25. Which imaging modality is preferred for routine surveillance of liver tumors in tyrosinemia patients?

• Brain MRI
• Abdominal ultrasound
• DEXA scan
• Lower limb X-ray

Correct Answer: Abdominal ultrasound

Q26. Which of the following biochemical tests helps distinguish Tyrosinemia Type II from Type I?

• Measurement of urinary succinylacetone
• Measurement of urinary homogentisic acid
• Serum lactate dehydrogenase
• Serum bilirubin fractionation

Correct Answer: Measurement of urinary succinylacetone

Q27. Which organ is the main site of pathology in Tyrosinemia Type I?

• Heart
• Liver
• Pancreas
• Thyroid

Correct Answer: Liver

Q28. A B. Pharm student counseling a family should advise that NTBC therapy primarily aims to:

• Replace the missing FAH enzyme
• Prevent formation of toxic metabolites and protect liver and kidneys
• Increase dietary tyrosine to correct deficiency
• Eliminate the need for any monitoring

Correct Answer: Prevent formation of toxic metabolites and protect liver and kidneys

Q29. Which urine finding is diagnostic for untreated Tyrosinemia Type I?

• Elevated urobilinogen only
• Presence of succinylacetone
• High ketone bodies without organic acids
• Marked proteinuria only

Correct Answer: Presence of succinylacetone

Q30. In the tyrosine catabolic pathway, which metabolite is formed immediately before fumarylacetoacetate?

• Homogentisate
• Methylmalonate
• Maleylacetoacetate
• Succinylacetone

Correct Answer: Maleylacetoacetate

Q31. Which supportive therapy is important in infants with Fanconi syndrome due to tyrosinemia?

• Vitamin D and phosphate supplementation for rickets
• High-sodium diet
• Routine iron chelation
• Beta-blocker therapy

Correct Answer: Vitamin D and phosphate supplementation for rickets

Q32. Which of the following best describes the role of succinylacetone as a diagnostic biomarker?

• It is nonspecific and elevated in many liver diseases
• It is a pathognomonic marker for Type I tyrosinemia when elevated
• It indicates vitamin B12 deficiency
• It reflects dietary protein intake only

Correct Answer: It is a pathognomonic marker for Type I tyrosinemia when elevated

Q33. Which medication interaction is relevant when dispensing NTBC?

• NTBC is contraindicated with acetaminophen due to liver toxicity
• NTBC may raise plasma tyrosine and necessitate monitoring when combined with high-protein supplements
• NTBC prevents absorption of oral antibiotics
• NTBC causes rapid metabolism of statins

Correct Answer: NTBC may raise plasma tyrosine and necessitate monitoring when combined with high-protein supplements

Q34. Which clinical presentation should prompt immediate evaluation for Tyrosinemia Type I in an infant?

• Persistent jaundice with hepatomegaly and failure to thrive
• Isolated mild cough
• Asymptomatic elevated cholesterol
• Intermittent rhinorrhea

Correct Answer: Persistent jaundice with hepatomegaly and failure to thrive

Q35. Molecular genetic testing in tyrosinemia primarily identifies mutations in which type of gene?

• Oncogene
• Enzyme-coding gene involved in tyrosine catabolism
• Mitochondrial tRNA gene
• Structural collagen gene

Correct Answer: Enzyme-coding gene involved in tyrosine catabolism

Q36. Which metabolic therapy is contraindicated as a sole treatment in Tyrosinemia Type I?

• Nitisinone combined with dietary restriction
• Liver transplantation in advanced disease
• Dietary tyrosine/phenylalanine restriction alone without NTBC in acute Type I
• Supportive therapy for rickets

Correct Answer: Dietary tyrosine/phenylalanine restriction alone without NTBC in acute Type I

Q37. The presence of which clinical triad suggests Tyrosinemia Type I?

• Skin hyperpigmentation, diabetes, neuropathy
• Hepatomegaly/jaundice, renal tubular dysfunction, porphyria-like crises
• Cardiomyopathy, cataracts, hearing loss
• Recurrent infections, eczema, alopecia

Correct Answer: Hepatomegaly/jaundice, renal tubular dysfunction, porphyria-like crises

Q38. In addition to NTBC therapy, which specialist involvement is typically required for comprehensive care?

• Cardiologist only
• Multidisciplinary team including metabolic specialist, dietitian, hepatologist, and ophthalmologist
• Dermatologist only
• Orthopedic surgeon only

Correct Answer: Multidisciplinary team including metabolic specialist, dietitian, hepatologist, and ophthalmologist

Q39. Which lab abnormality is most directly attributable to succinylacetone accumulation?

• Hypoglycemia due to increased insulin
• Inhibition of ALA dehydratase leading to elevated ALA and porphyrin precursors
• Reduced bilirubin production
• Increased serum creatinine only

Correct Answer: Inhibition of ALA dehydratase leading to elevated ALA and porphyrin precursors

Q40. Which of these is a reason liver transplantation might be indicated in Tyrosinemia Type I?

• Asymptomatic elevated tyrosine
• Refractory hepatic failure, progressive cirrhosis, or hepatocellular carcinoma despite NTBC
• Mild corneal irritation only
• Transient rash controlled by topical therapy

Correct Answer: Refractory hepatic failure, progressive cirrhosis, or hepatocellular carcinoma despite NTBC

Q41. Which newborn screening sample is typically used to measure succinylacetone for tyrosinemia detection?

• Plasma collected by venipuncture
• Dried blood spot (heel prick)
• Hair sample
• Urine collected at 24 hours

Correct Answer: Dried blood spot (heel prick)

Q42. Among the following, which dietary approach is recommended for patients on NTBC?

• No dietary restriction is needed once on NTBC
• Moderate restriction of tyrosine and phenylalanine with specialized amino-acid formulas as needed
• High-tyrosine, high-protein diet to compensate enzyme deficiency
• Complete elimination of all dairy products only

Correct Answer: Moderate restriction of tyrosine and phenylalanine with specialized amino-acid formulas as needed

Q43. Which ocular manifestation should be monitored in patients receiving NTBC due to elevated tyrosine?

• Retinal detachment
• Corneal crystals and keratitis
• Macular degeneration
• Uveitis only

Correct Answer: Corneal crystals and keratitis

Q44. Which pharmacodynamic effect explains why NTBC reduces succinylacetone levels?

• Direct enzymatic degradation of succinylacetone
• Upstream blockade preventing formation of fumarylacetoacetate and its derivatives
• Enhanced renal excretion of succinylacetone
• Activation of FAH enzyme

Correct Answer: Upstream blockade preventing formation of fumarylacetoacetate and its derivatives

Q45. Which symptom is more typical of Tyrosinemia Type III than Types I or II?

• Severe neonatal liver failure
• Neurological symptoms such as ataxia and intellectual disability
• Palmoplantar hyperkeratosis
• Renal tubular dysfunction

Correct Answer: Neurological symptoms such as ataxia and intellectual disability

Q46. For quality control, pharmaceutical students should know that NTBC tablets should be stored how?

• Frozen at -20°C
• At room temperature, protected from moisture and light per manufacturer recommendations
• Refrigerated at 2–8°C in all settings
• Exposed to direct sunlight to maintain potency

Correct Answer: At room temperature, protected from moisture and light per manufacturer recommendations

Q47. Which of the following best describes the role of FAH in normal metabolism?

• Catalyzes the conversion of tyrosine to phenylalanine
• Hydrolyzes fumarylacetoacetate to fumarate and acetoacetate in tyrosine degradation
• Converts homogentisate to maleylacetoacetate
• Transaminates tyrosine to p-hydroxyphenylpyruvate

Correct Answer: Hydrolyzes fumarylacetoacetate to fumarate and acetoacetate in tyrosine degradation

Q48. Which monitoring parameter best indicates risk reduction for porphyria-like crises on treatment?

• Normalization of plasma succinylacetone
• Lowered serum cholesterol
• Increased hemoglobin only
• Decreased creatine kinase

Correct Answer: Normalization of plasma succinylacetone

Q49. Which pharmacotherapeutic concept is important for B. Pharm students regarding NTBC prescription?

• NTBC is an enzyme replacement therapy administered intravenously
• NTBC is an enzyme inhibitor administered orally and requires lifelong adherence and monitoring
• NTBC requires no dietary counseling
• NTBC cures all types of tyrosinemia permanently

Correct Answer: NTBC is an enzyme inhibitor administered orally and requires lifelong adherence and monitoring

Q50. Which of the following best summarizes the multidisciplinary goals in managing a patient with Tyrosinemia Type I?

• Focus only on acute liver surgery
• Prevent toxic metabolite accumulation, protect liver and kidneys, monitor for malignancy, and optimize nutrition and growth
• Treat only ocular symptoms and ignore metabolic control
• Provide immunizations only

Correct Answer: Prevent toxic metabolite accumulation, protect liver and kidneys, monitor for malignancy, and optimize nutrition and growth

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com