Disorders of heme biosynthesis
| A | Acute intermittent porphyria | |
| B |
Congenital erythropoietic porphyria |
|
| C |
Infectious mononucleosis |
|
| D |
Kawasaki disease |
A girl on sulphonamides developed abdominal pain and presented to emergency with seizure. What is the probable diagnosis?
| A |
Acute intermittent porphyria |
|
| B |
Congenital erythropoietic porphyria |
|
| C |
Infectious mononucleosis |
|
| D |
Kawasaki disease |
- Barbiturate
- Chloramphenicol
- Sulfonamides
- Thiopental Na
- Oral contraceptives
- Phenylbutazone
- Rifampicin
A 27-year-old woman goes to an emergency room with severe abdominal pain. She had previously experienced similar episodes of pain that lasted several hours to a few days, but this episode is the most severe. She has also been experiencing nausea, vomiting, and constipation. The physician is left with the impression that she is agitated and somewhat confused, and an accurate history is difficult to elucidate. The patient is sent for emergency laparotomy, but no pathology is noted at surgery. Following the unrevealing surgery, an older surgeon comments that he had once seen a similar case that was actually due to porphyria.The porphyrias are biochemical abnormalities in which of the following pathways?
| A |
Glycogen degradation |
|
| B |
Heme synthesis |
|
| C |
Lipoprotein degradation |
|
| D |
Nucleotide degradation |
The porphyrias are a group of rare, related diseases that have in common a block in the heme synthesis pathway. The block is usually partial rather than complete, and thus many of these patients have only intermittent symptoms. Most cases of porphyria present with either a neurovisceral pattern (including both psychiatric symptoms and abdominal pain) or with photosensitive skin lesions. These two patterns are associated with different forms of porphyria.
Must know:
- Associate abnormalities of glycogen degradation (with the glycogen storage diseases, such as Von Gierke disease, Pompe disease, and Forbes disease.
- Associate abnormalities of lipoprotein degradation with some forms of hyperlipoproteinemia (notably Type I).
- Associate abnormalities of nucleotide degradation with Gout and Lesch-Nyhan syndrome.
| A |
PBG deaminase |
|
| B |
Uroporphyrin II cosynthetase |
|
| C |
Coprophyrin |
|
| D |
Ferrochelatase |
– Erythropoietic protoporphyria is due to deficiency of enzyme ferrochelataseQ.
– All porphyrias are autosomal dominant (AD) except congenital erythropoietic porphyria (autosomal recessive, AR), ALA dehydratase (porphobilinogen) deficiency (AR) and X-linked protoporphyria (X-linked).
| A | Acute Intermittent Porphyria | |
| B |
Congenital Erythropoietic Porphyria |
|
| C |
Porphyria Cutanea Tarda |
|
| D |
Hereditary Coproporphyria |
Ans. is ‘b’ i.e., Congenital erythropoietic porphyria
Inheritance of Porphyrias
Autosomal dominant Autosomal Recessive X-linked
o Acute intermittent porphyria (AIP) o ALA dehydratase deficiency o X-linked protoporphyria
o Porphyria cutanea Tarda (PCT) o Congenital erythropoietic porphyria
o Hereditary coproporphyria (HCP) o Erythropoietic protoporphyria o Variegate porphyria (VP)
| A | Uroporphyrinogen synthase | |
| B |
Uroporphyrinogen decarboxylase |
|
| C |
Protoporphyrinogen oxidase |
|
| D |
Coproporphyrinogen oxidase |
Ans.a. Uroporphyrinogen synthase
(Ref Harper 29/e p3l2-314, 27/e p277)
In porphyrias, uroporphyrinogen synthase enqlme defects lead to Acute Intemittent Porphyria, which shows purely
ne urological manifestation witho ut photosensitivity.
Which of the following porphyria does not have cutaneous lesions and phototoxicity?
| A |
Erythropoietic porphyria |
|
| B |
Porphyria cutanea tarda |
|
| C |
Acute intermittent porphyria |
|
| D |
Hereditary coproporphyria |
Ans. is ‘c’ i.e., Acute intermittent porphyria
| Type of Porphyria | Neuropsychiatric symptoms | Skin symptoms/Phototoxicity |
|
Hepatic porphyrias Acute intermittent porphyria 5-ALA dehydratase deficiency Hereditary coproporphyria Variegate porphyria Porphyria cutanea tarda |
+ + + + _ |
_ _ + + +
|
|
Erythropoietic porphyrias
Erythropoietic protoporphyria Congenital erythropoietic porphyria X-linked sideroblastic anemia |
_ _ _ |
+ + _ |
Disorders of heme biosynthesis
Disorders of heme biosynthesis
| A | Acute intermittent porphyria | |
| B |
Congenital erythropoietic porphyria |
|
| C |
Infectious mononucleosis |
|
| D |
Kawasaki disease |
A girl on sulphonamides developed abdominal pain and presented to emergency with seizure. What is the probable diagnosis?
| A |
Acute intermittent porphyria |
|
| B |
Congenital erythropoietic porphyria |
|
| C |
Infectious mononucleosis |
|
| D |
Kawasaki disease |
- Barbiturate
- Chloramphenicol
- Sulfonamides
- Thiopental Na
- Oral contraceptives
- Phenylbutazone
- Rifampicin
A 27-year-old woman goes to an emergency room with severe abdominal pain. She had previously experienced similar episodes of pain that lasted several hours to a few days, but this episode is the most severe. She has also been experiencing nausea, vomiting, and constipation. The physician is left with the impression that she is agitated and somewhat confused, and an accurate history is difficult to elucidate. The patient is sent for emergency laparotomy, but no pathology is noted at surgery. Following the unrevealing surgery, an older surgeon comments that he had once seen a similar case that was actually due to porphyria.The porphyrias are biochemical abnormalities in which of the following pathways?
| A |
Glycogen degradation |
|
| B |
Heme synthesis |
|
| C |
Lipoprotein degradation |
|
| D |
Nucleotide degradation |
The porphyrias are a group of rare, related diseases that have in common a block in the heme synthesis pathway. The block is usually partial rather than complete, and thus many of these patients have only intermittent symptoms. Most cases of porphyria present with either a neurovisceral pattern (including both psychiatric symptoms and abdominal pain) or with photosensitive skin lesions. These two patterns are associated with different forms of porphyria.
Must know:
- Associate abnormalities of glycogen degradation (with the glycogen storage diseases, such as Von Gierke disease, Pompe disease, and Forbes disease.
- Associate abnormalities of lipoprotein degradation with some forms of hyperlipoproteinemia (notably Type I).
- Associate abnormalities of nucleotide degradation with Gout and Lesch-Nyhan syndrome.
| A |
PBG deaminase |
|
| B |
Uroporphyrin II cosynthetase |
|
| C |
Coprophyrin |
|
| D |
Ferrochelatase |
– Erythropoietic protoporphyria is due to deficiency of enzyme ferrochelataseQ.
– All porphyrias are autosomal dominant (AD) except congenital erythropoietic porphyria (autosomal recessive, AR), ALA dehydratase (porphobilinogen) deficiency (AR) and X-linked protoporphyria (X-linked).
| A | Acute Intermittent Porphyria | |
| B |
Congenital Erythropoietic Porphyria |
|
| C |
Porphyria Cutanea Tarda |
|
| D |
Hereditary Coproporphyria |
Ans. is ‘b’ i.e., Congenital erythropoietic porphyria
Inheritance of Porphyrias
Autosomal dominant Autosomal Recessive X-linked
o Acute intermittent porphyria (AIP) o ALA dehydratase deficiency o X-linked protoporphyria
o Porphyria cutanea Tarda (PCT) o Congenital erythropoietic porphyria
o Hereditary coproporphyria (HCP) o Erythropoietic protoporphyria o Variegate porphyria (VP)
| A | Uroporphyrinogen synthase | |
| B |
Uroporphyrinogen decarboxylase |
|
| C |
Protoporphyrinogen oxidase |
|
| D |
Coproporphyrinogen oxidase |
Ans.a. Uroporphyrinogen synthase
(Ref Harper 29/e p3l2-314, 27/e p277)
In porphyrias, uroporphyrinogen synthase enqlme defects lead to Acute Intemittent Porphyria, which shows purely
ne urological manifestation witho ut photosensitivity.
Which of the following porphyria does not have cutaneous lesions and phototoxicity?
| A |
Erythropoietic porphyria |
|
| B |
Porphyria cutanea tarda |
|
| C |
Acute intermittent porphyria |
|
| D |
Hereditary coproporphyria |
Ans. is ‘c’ i.e., Acute intermittent porphyria
| Type of Porphyria | Neuropsychiatric symptoms | Skin symptoms/Phototoxicity |
|
Hepatic porphyrias Acute intermittent porphyria 5-ALA dehydratase deficiency Hereditary coproporphyria Variegate porphyria Porphyria cutanea tarda |
+ + + + _ |
_ _ + + +
|
|
Erythropoietic porphyrias
Erythropoietic protoporphyria Congenital erythropoietic porphyria X-linked sideroblastic anemia |
_ _ _ |
+ + _ |
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