Chempath 8: Porphyrias

Question 1

Porphyrias are caused by enzyme deficiency in the …………. synthesis pathway

Answer 1

Haem

Question 2

acute intermittent porphyria (AIP) presents with ………… but not …………..

Answer 2

Neurovisceral signs

Skin lesions

Question 3

hereditary corporphyria (HCP) and variegate porphyria (VP) present with ………. and ……………

Answer 3

Neurovisceral signs

Skin lesions

Question 4

congenital (CEP) erythropoietic protoporphyria (EPP) and porphyria cutanea trade (PCT) are the 3 non acute porphyria and present with …………. only.

Answer 4

Skin lesions

Question 5

List some Skin lesions seen in porphyrias?

Answer 5

Blisters
skin fragility
pigmentation

Question 6

choose the most common porhyria out of this list ?

A) CEP
B) EPP
C) PCT
D) HCP
E) VP
F) AIP

Answer 6

PCT

Porphyria cutanea tarda is the most common porphyria most likely because it can be acquired sporadically It presents with skin lesions as well as neurovisceral signs and is a non-acute porphyria.

Question 7

Which non-acute porphyria presents with skin lesions which are photosensitive and without blisters ?

Answer 7

EPP

Erythropoietic protoporphyria is a non-acute porphyria which means it only has skin lesions and no neurovisceral signs. This non-acute porphyria does not have blisters

Question 8

Why do HCP and VP have both skin lesions and neurovisceral lesions?

Answer 8

HCP - hereditary corporphyria is caused by deficiency in corporphyrinogen oxidase. This causes excess Uroporphyrinogen 3 oxidase which causes skin lesions if exposed to UV light. Uroporphyrinogen 3 oxidase also has negative feedback on HMB synthase which causes build up of PBG. PBG causes neurovisceral lesions.

VP is similar but different enzyme deficiency.

Question 9

List 3 ALA synthase inducers which can trigger AIP ?

Answer 9

• Steroids
• Alcohol
• COCP

Question 10

How is AIP inherited ?

Answer 10

Autosomal dominant

Question 11

Which disease is caused by a mutation in the gene encoding ALA synthase ?

Answer 11

X-linked sideroblastic anaemia

Question 12

List 4 symptoms of AIP ?

Answer 12

4 Ps

Psychological disturbance
Painful abodmen
polyneuropathy
Port wine coloured urine (porphobilinogen oxidises in light and turns a wine colour)

Only neuro-visceral symptoms