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Questions and Answers
What is the main reason for most porphyrias being autosomal dominant?
What is the main reason for most porphyrias being autosomal dominant?
- 50% reduction in enzyme activity is enough to cause disease
- 100% loss of function is lethal to the developing embryo (correct)
- Porphyrins are spontaneously oxidised to porphyrinogens
- Mutations affecting porphyrinogens are more common
Why do porphyrins react to UV light and cause skin damage?
Why do porphyrins react to UV light and cause skin damage?
- They transmit energy to water molecules
- They absorb light at 400nm and form oxygen radicals (correct)
- They absorb light at 700nm
- They form non-reactive compounds when exposed to light
What type of molecules mimic neurotransmitters and cause severe CNS dysfunction in some porphyrias?
What type of molecules mimic neurotransmitters and cause severe CNS dysfunction in some porphyrias?
- Porphyrins
- Porphyrinogens
- Precursors PBG and d-ALA (correct)
- Enzymes responsible for porphyrin synthesis
What is the consequence of a 100% loss of function of the enzyme in porphyrias?
What is the consequence of a 100% loss of function of the enzyme in porphyrias?
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How do porphyrins cause damage to the skin in sun-exposed areas?
How do porphyrins cause damage to the skin in sun-exposed areas?
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What severe CNS dysfunction is caused by the early precursors PBG and d-ALA in some porphyrias?
What severe CNS dysfunction is caused by the early precursors PBG and d-ALA in some porphyrias?
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What is the consequence of a 50% reduction in enzyme activity in most porphyrias?
What is the consequence of a 50% reduction in enzyme activity in most porphyrias?
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Why is a 100% loss of function lethal to the developing embryo in porphyrias?
Why is a 100% loss of function lethal to the developing embryo in porphyrias?
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How do some porphyrias cause severe CNS dysfunction?
How do some porphyrias cause severe CNS dysfunction?
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