Photosensitivity and the Porphyrias Flashcards Preview

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Flashcards in Photosensitivity and the Porphyrias Deck (24)
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1

What are the porphyrias?

A group of diseases which are caused due to an inborn error in the haem metabolism pathway, leading to the build-up of intermediate metabolites

2

How does porphyria cutanea tarda present?

Blistering, erosions and often milia on the face and backs of hands

3

How do sporadic cases of porphyria cutanea tarda classically show up in male and females respectively?

Males - Chronically high alcohol intake

Females - Taking oestrogen medications

4

Which porphyria is most common in Scotland?

Porphyria cutanea tarda

5

How is acute intermittent porphyria inherited?

AD

6

In which area of the world is acute intermittent porphyria particularly common?

Scandinavia

7

How does acute intermittent porphyria present?

Abdominal pain attacks

Neuropsychiatric symptoms

Dark urine

NO skin lesions

8

What actually causes the damage when porphyrins build up in the skin?

Sunlight activates porphyrins which promotes mediator release from surrounding inflammatory cells leading to a damaging inflammatory response

9

In which country is Variegate prophyria most common?

South Africa

10

How does varigate porphyria present?

Symptoms of both porphyria cutanea tarda and acute intermittent porphyria

  1. Blistering, erosis and milia on the face and backs of hands
  2. Acute abdominal pain, dark urine, neuropsychiatric symptoms

11

What are porphyrins?

Intermediates within the haem synthesis pathway

Molecules are roughly circular in shape and may react to EM radiation

12

How is congenital erythropoietic porphyria inherited?

AR

13

Which enzyme in the haem synthesis pathway has undergone a mutation in congenital erythropoietic porphyria?

Uroporphyrinogen III co-synthase

14

Congenital erythropoietic porphyria involves a build up of which porphyrin in the body?

Hydromethylbilane

15

How does congenital erythropoietic porphyria present?

Blistering (and scarring) of the skin

Hairy skin

Brown teeth

Haemolytic anaemia

Pink fluorescing urine

16

How many enzymes are in the haem synthesis pathway?

8

17

The lak of activity from which enzyme is responsible for causing porphyria cutanea tarda?

Uroporphyrinogen decarboxylase

18

Which colour will a patient's urine fluoresce under Wood's lamp if they are suffering from porphyria cutanea tarda?

Coral pink

19

Which inherited porphyria is most common in Scotland?

Erythropoietic protoporphyria

(porphyria cutanea tarda is the most common overall by 80% of cases are sporadic)

20

Why may nerve damage occur in a patient with acute intermittent porphyria?

There is a build up of porphobilnogen (PBG) due to lack or absence of functioning PBG deaminase

21

Eryhtropoietic and erythrohepatic protoporphyrias are most highly sensitive to which type of EM radiation?

UV B

22

At which stage in life does erythropoeitic protoporphyria present?

Early childhood

23

How does erythropoeitic protoporphyria present?

Discomfort, itch or tingling in sun exposed skin

There are often no clinical signs

24

Build up of which porphyrin, and lack of which functioning enzyme, causes erythropoietic protoporphyria?

Lack of ferrochelatase activity

Build up of protoporphyrin IX