Amino acid metabolism and disorders US Medical PG Flashcards - Medical Study Cards
Master Amino acid metabolism and disorders with OnCourse flashcards. These spaced repetition flashcards are designed for medical students preparing for NEET PG, USMLE Step 1, USMLE Step 2, MBBS exams, and other medical licensing examinations.
Amino acid metabolism and disorders Flashcard Deck - 10 Cards
Flashcard 21: What is the underlying defect in Hartnup disease?
Answer: Defect in the neutral amino acid transporter (e.g., tryptophan) in the proximal renal tubular cells and enterocytes.
Extra: - Clinical presentation: Pellagra-like symptoms (dermatitis, diarrhea, dementia, ataxia) because tryptophan is a precursor for Niacin (Vitamin B3).
- Inheritance: Autosomal Recessive (AR).
- Diagnostic feature: Neutral aminoaciduria.
- Treatment: High-protein diet and Nicotinic acid supplementation.
Flashcard 22: What is the inheritance and clinical hallmark of G6PD deficiency?
Answer: X-linked recessive deficiency of glucose-6-phosphate dehydrogenase, leading to inability to detoxify ROS and subsequent episodic hemolytic anemia.
Extra: - Pathophysiology: Reduced NADPH → Reduced Glutathione → Oxidative Stress.
- Triggers: Fava beans, Infections, Drugs (Sulfa, Primaquine, Nitrofurantoin).
- Morphology: Heinz bodies (denatured Hb), Bite Cells (splenic macrophage action).
- Genetics: X-linked Recessive (XR).
- Populations: African (G6PD-), Mediterranean (G6PD Mediterranean).
Flashcard 23: What are the clinical features of galactokinase deficiency?
Answer: Galactosemia, galactosuria, and infantile cataracts (may present as failure to track objects or develop social smile).
Extra: - Inheritance: Autosomal Recessive (AR).
- Pathophysiology: Deficiency of galactokinase leads to accumulation of galactose, which is converted to galactitol by aldose reductase.
- Accumulation of galactitol in the lens causes osmotic damage and cataracts.
- Clinical Pearl: This is a milder form of galactosemia compared to Classic Galactosemia (GALT deficiency). Cataracts may be the only presenting sign.
Flashcard 24: What is the enzyme deficiency in classic galactosemia?
Answer: Deficiency of Galactose-1-phosphate uridyltransferase (GALT)
Extra: • Inheritance: Autosomal Recessive (AR)\n• Accumulation: Galactose-1-phosphate and galactitol (sequesters phosphate).\n• Clinical Features: Failure to thrive, jaundice, hepatomegaly, infantile cataracts, intellectual disability.\n• Treatment: Exclude galactose and lactose from diet.
Flashcard 25: lactase deficiency (lactose intolerance)
Answer: hereditary, age-dependent, or post-gastroenteritis
Extra: Bloating, cramps, osmotic diarrhea after dairy meal. Management: restrict dairy intake, lactase supplementation.
Flashcard 26: What isomer of amino acids are found in proteins?
Answer: L-form only
Flashcard 27: What are the clinical features and management of pyruvate dehydrogenase complex (PDC) deficiency?
Answer: Neurologic deficits, lactic acidosis (metabolic acidosis), and increased serum alanine. Treatment: Ketogenic diet (high Lysine and Leucine).
Extra: Pyruvate Dehydrogenase Complex (PDC) deficiency:
- Mechanism: Pyruvate cannot be converted to Acetyl-CoA, leading to shunting of pyruvate to lactate (via LDH) and alanine (via ALT).
- Genetics: Most common cause is X-linked mutation in the E1-alpha subunit.
- Treatment: High fat / ketogenic diet. Lysine and Leucine are the only purely ketogenic amino acids; they bypass the PDH complex to provide energy via Acetyl-CoA.
Flashcard 28: s-adenosyl methionine (SAM)
Answer: methyl groups
Flashcard 29: glutamine-PRPP amidotransferase
Answer: de novo purine synthesis
Extra: Feedback inhibited by: AMP, IMP, GMP.
Flashcard 30: If an enyzme is a carboxylase, what do you know about its function?
Answer: transfers CO2 groups with help of biotin
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