Aani CP: Haem Synthesis Flashcards

1
Q

Which cells do porphyrias affect? (2)

A

Liver cells and Erythroid cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is liver cytochrome needed for?

A

Detoxification of drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is haem cytochrome needed for?

A

Electron transport chain in mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is at the start of the haem synthesis chain?

A

Succinyl CoA + Glycine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which enzyme is needed to convert Succinyl Co-A and Glycine into 5 Aminolaeuvulinic Acid (ALA)?
Where does this reaction take place?

A

ALA Synthase

In the mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does 5 ALA turn into? Which enzyme is used?

A

PBG (porphobilinogen) using PBG synthase or ALA dehydratase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does PBG turn into? Which enzyme is used?

A

HMB (hydroxymethylbilane) using HMB synthase of PBG deaminase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does HMB turn into? Which enzyme is used?

A

Uroporphyrinogen III and Uroporphyrinogen I using uroporphyrinogen III synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does Uroporphyrinogen III turn into? Which enzyme is used?

A

Coproporphyrinogen III using Uroporphyrinogen III decarboxylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which mnemonic is used to remember the molecule order for haem synthesis?

A

Suhaila & Ghausal

ALA Placed Hot Urine Cup Produces Perfect Haem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does Coproporphyrinogen III turn into? Which enzyme is used? Where does this reaction take place?

A

Protoporphyrinogen 9 using coproporphyrinogen oxidase. Takes place in mitochondrial wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does Protoporphyrinogen 9 turn into? Which enzyme is used?

A

Protoporphyrin 9 using Protoporphrinogen oxidase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does Protoporphyrin turn into? Which enzyme is used?

A

HAEM! Using Ferrochetalase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the triad of symptoms in acute Porphyrias?

A

Abdo pain
Psych symptoms
Neurological/neurovisceral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which enzyme is affected in Acute Intermittent Porphyria? (AIP)

A

HMB synthase (How My Bear? - aCUTE)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ferrochetalase error causes which condition?

A

EPP: Erythropoeitic Protoporphyria

17
Q

What will accumulate in urine in AIP?

A

HMB synthase deficiency so whatever comes before HMB will rise i.e. PBG and ALA will rise. Both will be seen in urine –> Port wine urine

18
Q

Name some triggers of AIP

A

BASS: Chloe Bass has AIP

Barbituates
Alcohol (Ethanol)
Stress
Steroids

19
Q

Describe the features of AIP

A

Acutre triad: neurovisceral, abdo pain, psych disrburbance
Neurovisceral (tummy pain etc)
No skin lesion

20
Q

Treatment of AIP

A
  1. Carbohydrates (IV or food) will turn of ALA synthase to stop ALA accumulation –> stop symtpoms.
  2. Haem Arginate also inhibits ALA synthase
21
Q

What condition do you get if you have a PBG synthase deficiency? (remember other name for PBG synthase)

A

PBG synthase = ALA dehydratase.

You get ALA Dehydratase Deficiency Porphyria

22
Q

What are the symptoms of ALA Dehydratase Deficiency Porphyria?

A

Acute: Rise in ALA –> Neurovisceral symptoms

23
Q

What kind of symptoms does a high ALA cause?

A

Neurovisceral - autonomic neuropathy (abdo pain, vomiting)

24
Q

Why are there neurovisceral symptoms in HCP?

A

HCP = hereditary coproporphyria.
This is a deficiency in Coproporphyrinogen Oxidase. This means Coproporphyrinogen III rises, this inhibits HMB synthase. HMB synthase inhibition leads to a rise in PBG and ALA –> Neurovisceral symptoms

25
Q

What condition do you get when there is a deficiency in coproporphyrinogen oxidase?

A

Hereditary Coproporphyria

26
Q

What are the 3 cutaneous only (skin-lesion non-acute) porphyrias?

A

Congenital Erythropoietic Porphyria (CEP)
Porphyria Cutanea Tarda (PCT)
Erythropoietic Protoporphyria (EPP)

27
Q

Which 2 molecules are least soluble (therefore useful for testing)

A
Uroporphyrinogen III (seen in urine) 
Coproporphyrinogen III (seen in stool)
28
Q

What is variegate Porphyria (VP)?

A

Deficiency in Protoporphyrinogen Oxidase

29
Q

What condition do you get if you have a deficiency in Uroporphyrinogen decarboxylase?

A

Porphyria Cutanea Tarda

30
Q

What are the symptoms of Variegate Porphyria?

A

Variegate Porphyria is a deficiency in Protoporphyrinogen oxidase. Neurovisceral with skin lesions (on back of hand/neck).
Neurovisceral because there is an accumulation of Protoporphyrinogen 9 which inhibits HMB synthase which causes a rise in ALA –> neurovisceral

31
Q

Why are skin lesions caused in some porphyrias?

A

Skin lesions occur when there is a rise in porphyrinogens because they are oxidised to porphyrin

32
Q

Which porphyrias cause skin lesions?

A

The ones that cause a rise in porphyrinogens or HMB:

  1. Porphyria Cutanea tarda (low uroporphyrinogen III decarboxylase —> high Uroporphyrinogen III)
  2. Congenital Erythropoietic Porphyria (ECP) (Low Uroporphyrinogen III synthase —> High HMB)
  3. Erythropoietic Protoporphyria (EPP) (Low Ferrochatalase so a build up in Proroporphyrin)
  4. Variegate Porphyria (VP) (Low Protoporphyrinogen Oxidase so a build up of Protoporphyrinogen 9)
  5. Hereditary Coproporphyria (HCP) (Low Coproporphyrinogen Oxidase so a build up of Coproporphyrinogen 3)
33
Q

Which mnemonic do I use to remember the Porphyrias?

A

Awww Acute Con, Probably Has Various Estates:

Ala deyhdratase deficiency porphyria
Acute Intermittent Porphyria (AIP)
Congenital Erythropoietic Porphyria (CEP)
Porphyria Cutanea Tarda (PCT)
Hereditary Coproporphyria (HCP)
Variegate Porphyria (VP)
Erythropoeitic Porphyria
34
Q

Are porphorinogens colourful or colourless?

A

They are colourless pre-cursors

35
Q

Are porphyrins colourful or colourless?

A

Colourful - purple!

36
Q

Which are the 2 blistering Porphyrias?

A

Porphyria Cutaenea Tarda (PCT)

Congenital Erythropoeitic Porphyria (CEP)

37
Q

What causes Erythropoeitic Protoporphyria (EPP)?

A

Absence of ferrochetalase therefore a build up of protoporphyrin 9

38
Q

What are the features of EPP?

A

Non blistering rash, itching etc following sun exposure (sun exposure = red cell porphyria which is the Erythropoeitic one)