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Questions and Answers
What is the primary consequence of the defect in the enzyme homogentisate 1,2-dioxygenase in alkaptonuria?
What is the primary consequence of the defect in the enzyme homogentisate 1,2-dioxygenase in alkaptonuria?
Which medical condition is characterized by the accumulation of phenylalanine in the blood, potentially leading to brain damage if untreated?
Which medical condition is characterized by the accumulation of phenylalanine in the blood, potentially leading to brain damage if untreated?
Which enzyme's absence is primarily responsible for hereditary tyrosinemia?
Which enzyme's absence is primarily responsible for hereditary tyrosinemia?
Which symptom is NOT typically associated with acute tyrosinemia in infants?
Which symptom is NOT typically associated with acute tyrosinemia in infants?
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In which condition would you most likely observe ectopia lentis as a phenotypic expression?
In which condition would you most likely observe ectopia lentis as a phenotypic expression?
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What is a common consequence of excessive alkapton in the body?
What is a common consequence of excessive alkapton in the body?
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Which metabolic product accumulates significantly in individuals with untreated phenylketonuria?
Which metabolic product accumulates significantly in individuals with untreated phenylketonuria?
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What symptom is commonly observed in chronic tyrosinemia?
What symptom is commonly observed in chronic tyrosinemia?
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Study Notes
Alkaptonuria
- Definition: Rare genetic disorder affecting phenylalanine and tyrosine metabolism.
- Cause: Defect in the enzyme homogentisate 1,2-dioxygenase, hindering tyrosine breakdown.
- Mechanism: Homogentisic acid (alkapton) builds up in blood and urine.
- Consequences: Cartilage damage (ochronosis, osteoarthritis), heart valve issues, kidney stones possible. Urine turns black/red when exposed to air.
- Diagnosis: Paper/TLC, plasma, and urine tests (plasma level: 6.6 mg/ml, urine level: 3.12 mmol/mmol of creatinine).
Phenylketonuria (PKU)
- Description: A silent disorder, causing potential brain damage and developmental disabilities if untreated.
- Cause: Accumulation of phenylalanine in the blood, 30-50 times higher than normal.
- Consequences: Behaviour disorders, cataracts, skin disorders, movement disorders.
- Mechanism: Accumulation of phenylalanine leads to phenylalanine metabolites (phenylpyruvate, phenylacetate, phenyllactate.)
Ornithine Transcarbamylase (Urea Cycle Disorder)
- Type 2: Acute metabolic crisis, potentially life-threatening in infancy.
- Symptoms: Vomiting, respiratory distress, lethargy, coma possible.
Tyrosinemia
- Description: Hereditary genetic IEM, autosomal recessive, linked to severe liver disease in infancy.
- Cause: Absence of the enzyme fumarylacetoacetate hydrolase (FAH).
- Consequences: Accumulation of toxic metabolic products harming liver and kidneys.
Acute Tyrosinemia
- Symptoms: Poor weight gain, enlarged liver/spleen, distended abdomen, leg swelling, increased bleeding tendencies.
- Outcome: Often fatal between 3-9 months without liver transplant.
Chronic Tyrosinemia
- Symptoms: Enlarged liver/spleen, distended abdomen, poor weight gain, frequent vomiting/diarrhea.
- Outcome: Usually develops cirrhosis, requires liver transplant.
Homocystinuria
- Features in symptoms/expression: Ectopia lentis (displacement of the lenses), vascular occlusive disease, malar flush, osteoporosis, homocysteine and methionine accumulation.
- Cause: Defective activity of cystathionine synthase.
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Description
Explore the rare genetic disorders Alkaptonuria and Phenylketonuria (PKU) in this quiz. Learn about their definitions, causes, mechanisms, consequences, and diagnostic methods. Test your knowledge on how these conditions affect metabolism and health.
