Question
Which one of the following disorders is caused by enzymatic defects in the heme biosynthesis pathway?
| A. |
Porphyrias
|
| B. |
Myelodysplastic syndrome
|
| C. |
Hemophilias
|
| D. |
Plasma cell disorders
|
Show Answer
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Correct Answer � A
Explanation
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|
Heme Biosynthesis and Porphyrias
- Heme is synthesized in a multi-step enzymatic pathway occurring in the mitochondria and cytoplasm.
- Porphyrias are a group of rare metabolic disorders caused by defects in enzymes involved in the heme biosynthesis pathway.
- These defects result in the accumulation of porphyrins or their precursors, leading to clinical manifestations.
Types of Porphyrias
- Acute Porphyrias
- Primarily affect the nervous system (e.g., Acute Intermittent Porphyria).
- Cutaneous Porphyrias
- Cause photosensitivity and skin lesions (e.g., Porphyria Cutanea Tarda).
Clinical Features
- Acute attacks: Abdominal pain, neurological symptoms, tachycardia.
- Cutaneous symptoms: Blistering and hyperpigmentation on sun-exposed areas.
Explanation of other options:
- B. Myelodysplastic Syndrome : A clonal disorder of hematopoietic stem cells, unrelated to the heme biosynthesis pathway.
- C. Hemophilias : A group of bleeding disorders due to clotting factor deficiencies, not related to heme synthesis.
- D. Plasma Cell Disorders : Disorders like multiple myeloma affect plasma cells but are unrelated to heme biosynthesis.
