1. The document discusses porphyrins and porphyria, focusing on haem synthesis, types of porphyria, and specific conditions like porphyria cutanea tarda and acute intermittent porphyria. 2. Haem is synthesized through 8 steps starting from glycine and succinyl-CoA and involving the mitochondria and cytoplasm. Deficiencies in enzymes in the pathway cause different types of porphyria. 3. The main types discussed are porphyria cutanea tarda, characterized by skin lesions and mutations in the UROD enzyme, and acute intermittent porphyria, which causes abdominal and neurological symptoms due to a PBGD enzyme defect.

1. HAEM SYNTHESIS
and PORPHYRIA
Dr. RANJAN DASH

2. HEADS TO BE HIGHLIGHTED UPON
 WHAT ARE PORPHYRINS
 SYNTHESIS OF HAEM
 TYPES OF PORPHYRIA
 PATHOPHYSIOLOGY AND MANAGEMENT
 SCOPE OF GENE THERAPY

3. Porphyrins : What are they ?
• Porphyrins are a group of heterocyclic organic
compounds, composed of four modified pyrrole
subunits interconnected at their α carbon atoms
via methine bridges (=CH−)
• The parent porphyrin is porphin, and substituted
porphines are called porphyrins
• One result of the large conjugated system is that
porphyrin molecules typically have very intense
absorption bands in the visible region and may be
deeply colored
• The name “porphyrin” comes from the Greek word
πορφύρα (porphyra), meaning purple
• one of the best-known porphyrins is haem, the
pigment in red blood cells, a cofactor of the
protein haemoglobin

4. Haem is present in
 Haemoglobin
 Myoglobin
 Cytochromes
 Peroxidase
 Catalase
 Tryptophan pyrrolase
 Nitric oxide synthase

5. Structure of Haem
• Haem is a derivative of the
porphyrin.
• Porphyrins are cyclic
compounds formed by
fusion of 4 pyrrole rings
linked by methenyl (=CH-)
bridges with iron at the
centre
Pyrrole ring

6. Structure of Haem
Since an atom of iron is present,
heme is a Ferroprotoporphyrin.
The pyrrole rings are named as I, II,
III, IV and the bridges as alpha, beta,
gamma and delta.
The possible areas of substitution
are denoted as 1 to 8.

7. Porphyrin Substituents

8. BIOSYNTHESIS OF HAEM
 Haem can be synthesized by almost all
the tissues in the body
 Haem is synthesized in the normoblasts,
but not in the matured erythrocytes
 The pathway is partly cytoplasmic and
partly mitochondrial

9. Site of Haem Synthesis

10. STEP 1 SYNTHESIS OF ALA
+
CoASH
GLYCINE SUCCINYL CoA
α Amino β ketoadipic Acid
ALA Synthase

11. Pyridoxal phosphate ALA Synthase
α-Amino-β-ketoadipic acid
δ-Aminolevulinate (ALA)
Rate controlling step
C02

12. STEP 2 SYNTHESIS OF PORPHOBILINOGEN
ALA dehydratase(zinc as cofactor)
2H2O -
δ-Aminolevulinate (ALA)
Porphobilinogen (PBG)
Lead

13. STEP 3 SYNTHESIS OF HYDROXYMETHYLBILANE
(HMB synthase/PBG deaminase)
4NH3
(condensation)
Porphobilinogen (PBG)
Hydroxymethylbilane(HMB)
(Linear tetrapyrrole)
AIP

14. STEP 4 FORMATION OF UPG III
spontaneous
recyclization
Uroporphyrinogen synthase III
Hydroxymethylbilane
Uroporphyrinogen I
Uroporphyrinogen III
CEP

15. STEP 5 FORMATION OF COPROPORPHYRINOGEN III
6H 6 H
Uropophyrin I Uroporphyrinogen decarboxylase Uroporphyrin III
Uroporphyrinogen III
Coproporphyrinogen III
Uroporphyrinogen I
Coproporphyrinogen I
PCT

16. STEP 6 FORMATION OF PROTOPORPHYRINOGEN III
Coproporphyrinogen oxidase
Coproporphyrinogen III
Protoporphyrinogen III
HEREDITARY COPROPORPHYRIA

17. STEP 7 SYNTHESIS OF PROTOPORPHYRIN IX
Protoporphyrinogen oxidase
Protoporphyrinogen III
VARIEGATE PORPHYRIA
Protoporphyrin IX

18. FINAL STEP CHELATION OF IRON TO FORM HAEM
Ferrochelatase Fe
(Haem synthase)
Protoporphyrin IX
HAEM
HEREDITARY
PROTOPORPHYRIA

19. SUMMARY OF SYNTHESIS OF HAEM

20. REGULATION OF HAEM SYNTHESIS
 ALA synthase is also allosterically inhibited by hematin
 The compartmentalization of the enzymes of haem synthesis ,the rate-limiting enzyme is in
the mitochondria
 Drugs like barbiturates induce heme synthesis and require the heme containing cytochrome
P450 for their metabolism
 The steps catalyzed by Ferrochelatase and ALA dehydratase are inhibited by lead

21. INH that decreases the availability of pyridoxal phosphate may also affect haem
synthesis
High cellular concentration of glucose prevents induction of ALA synthase
This is the basis of administration of glucose to relieve the acute attack of porphyrias
Uroporphyrinogen synthase and ferrochelatse mostly regulate haem formation in RBC

22. PORPHYRIA : Disorders of Haem
Synthesis
 are a group of inborn errors of metabolism associated with the
biosynthesis of heme. (Greek ‘porphura’ means purple)
 These are characterized by increased production and excretion of
porphyrins and or their precursors (ALA + PBG)
 Most of the porphyrias are inherited as autosomal dominant traits

24. PREVELANCE AND INHERITANCE PATTERN
 Based on European studies, the prevelance of the
most common porphyria, PCT, is 1 in 10,000
 The most common acute porphyria, AlP, is about 1
in 20,000,
 The most common erythropoietic porphyria,
EPP, is estimated at 1 in 50,000 to 75,000.
 CEP is extremely rare with prevalence estimates of
1 in 1,000,000 or less
 Only 6 cases of ADP are documented

25. TYPES OF PORPHYRIA
Broadly grouped into 3 types:
a. Hepatic porphyrias
b. Erythropoietic porphyrias
c. Porphyrias with both erythropoietic and hepatic abnormalities
This classification is based on the major site, where the enzyme deficiency
occurs, in erythropoietic cells of the bone marrow or in the liver

26. CLASSIFICATION FOR THE SIX COMMON
PORPHYRIAS
1 . Cutaneous disease only :
Porphyria cutanea tarda (PCT)
Congenital erythropoietic porphyria (CEP)
Erythropoietic protoporphyria (EPP)
2 . Cutaneous disease and Acute attacks :
Hereditary coproporphyria (HC)
Variegate porphyria (VP)
3. Acute attacks only : Acute intermittent porphyria (AIP)

27. Types of Porphyria Enzyme defect Characteristics
A IP Porphobilinogen deaminase Abdominal pain
Neuropsychiatric symptom
PCT Uroporphyrinogen
decarboxylase
photosensitivity
HCP Coproporphyrinogen oxidase Abdominal pain
neuropsychiatric symptom
photosensitivity
VP Protoporphyrinogen oxidase Abdominal pain
neuropsychiatric symptom
photosensitivity
HEPATIC PORPHYRIAS
Types of Porphyria Enzyme defect Characteristics
CEP Uroporphyrinogen synthase III Photosensitivity ,hemolysis
PROTOPORPHYRIA Ferrochelatase Photosensitivity
ERYTHROPOETIC PORPHYRIA

28. Enzyme Deficiencies in Porphyrias

30. PORPHYRIA CUTANEA TARDA

31. Risk Factors For Developing PCT
 Alcohol
 Hepatitis C infection,
 Oestrogens
 Haemochromatosis
 Drugs such as Barbiturates , Sulphonamides , OHAs, OCP, Tetracycline,
Phenytoin ,etc
 They all predispose to the inhibition of the UROD enzyme in the liver

32. CLINICAL FEATURES
 Commonest skin lesions seen are bullae, (painful) resolving over a few week
leaving atrophic scars, milia and often mottled hyper‐ or hypopigmentation.
 Other common features are:
 Patches of scarring alopecia following resolution of bullae on the scalp
 Hypertrichosis, usually on the upper face and forehead, ear and arm
 Hyperpigmentation in a melasma‐like pattern on the cheeks and around the eyes
 Diffuse pattern on light‐exposed skin, or occasionally in a reticulate distribution
 Photo‐induced onycholysis and accelerated solar elastosis
 Morphoea‐like plaques may develop particularly on the head and upper trunk

33. Images of PCT

34. Pathophysiology

35. Differential diagnosis
• VP , HCP
• Drug‐induced pseudoporphyria, renal pseudoporphyria
• Late‐onset Gunther disease or mild HEP
Biochemical findings
• In PCT, the urinary porphyrin concentration is increased, consisting
mainly of uroporphyrin, some heptacarboxylic acid
• Porphyrin, Isocoproporphyrin accumulates in the faeces.
• In patients with renal failure, faecal analysis is essential, The biochemical
marker of disease activity and response to treatment is quantitative urinary
• Porphyrin excretion measured in a random urine sample.

36. Histopathology
 The bullae in PCT are subepidermal with a sparse inflammatory
infiltrate and ‘festooning’ of dermal papillae into the bullae
 Deposition of PAS‐positive diastase‐resistant fibrillar glycoprotein material
in and around the upper dermal blood vessel walls
 Reduplication of the basement membrane.
 Immunofluorescence reveals IgG, a little IgM, fibrinogen and
complement at the epidermal–dermal junction

37. ACUTE INTERMITTENT PORPHYRIA

38. Etiopathogenesis
 Occurs due to the deficiency of the enzyme uroporphyrinogen I synthase
 Characterized by increased excretion of porphobilinogen and 6-aminolevulinate.
 The urine gets darkened on exposure to air due to the conversion of porphobilinogen to porphobilin
 Usually expressed after puberty in humans

39. Clinical features
 The symptoms include abdominal pain, vomiting , cardiovascular and neuropsychiatric
abnormalities
 Peripheral neuropathy (primarily motor , proximal symmetric )
 Sensory involvement: pain in extremities (muscle or bone pain), numbness, paresthesias,
and dysesthesias
 The symptoms are more severe after administration of drugs (e.g. barbiturates)
These patients are not photosensitive since the enzyme defect occurs prior to the formation
of uroporphyrinogen
Cranial nerve involvement (II ,VII,X)
Autonomic dysfunction and Hyponatremia ( SIADH )

40. Lab Findings
 Urine Porphobilinogen (increased) Levels of ALA and PBG are increased.
 Measurement of urinary ALA is less sensitive than PBG
 Erythrocyte PBGD activity is decreased in most AIP patients and
helps confirm the diagnosis in a patient with high PBG.
 A normal enzyme activity in erythrocytes does not exclude AIP

41. Treatment
 Intravenous hemin + symptomatic + supportive measures is the treatment of choice
 There is a favorable response to early treatment with hemin
 Stabilization of lyophilized hematin by reconstitution with 30% human albumin can prevent
local adverse effects
 Dosage : 3-4 mg/kg daily for 4 days

42. Complications
* Risk of advanced liver disease and Hepatocellular carcinoma
* Risk of chronic HTN & impaired renal function, with interstitial nephritis
* Posterior Reversible Encephalopathy Syndrome(PRES)

43. Prognosis
 recurrent attacks were most likely in acute porphyrias within the next 1-3 yr
 Improved outlook with early detection and treatment
Prevention
 Identify and remove inciting factors
 A well-balanced diet that is somewhat high in carbohydrate (60-70% of total calories)
 Correct Anemia.
 Hormonal therapy
 Hemin once or twice weekly can prevent frequent, noncyclic attacks

44. CONGENITAL ERYTHROPOETIC PORPHYRIA
(GUNTHER DISEASE)

45. Etiopathogenesis
 Caused by an autosomal recessive inherited deficiency of the Uroporphyrinogen III cosynthase enzyme
 Since this enzyme is required to form the biologically useful type III porphyrin isomers
its absence results in non‐enzymatic reactions producing large amounts of type I isomer
 These porphyrins which cannot participate in haem formation, and which massively accumulate in
erythroid cells and then gradually leak into the plasma

46. Clinical presentation
 Wide spectrum of presentation, from hydrops fetalis through to severe sign &symptoms at infancy
 The first sign of CEP is often the child’s mother noting brown discoloration of amniotic fluid
at the onset of labour, or observing pink or brown porphyrin staining of nappies
 Severe photosensitivity begins in infancy, often in the neonatal period, with blisters developing in
light‐exposed skin on minimal light exposure
 Phototherapy for neonatal jaundice may trigger lesions. Most children are so sensitive to the light that
they have problems throughout the year
 Repeated bouts of inflammation with vesicles and bullae, often complicated by secondary infection and
mutilating scarring, particularly of the face and hands
 This photomutilation is associated with erosion of the terminal phalanges, onycholysis and destructive
changes affecting the pinnae and nose

47. CEP cont…
Eyes : Keratoconjunctivitis, blepharitis, cataracts, corneal ulcers, scars, cicatricial ectropion and
scarring alopecia of eyelashes and eyebrows
Bones and teeth : stained brown , decreased bone density, osteopenia and osteolytic lesions secondary
to erosion by hyperplastic bone marrow vertebral compression and collapse with pathological fractures
resorption of terminal phalanges & acro‐osteolysis
Haematology : high concentrations of porphyrins in RBCs cause hemolytic anaemia, severe enough to
induce marrow hyperplasia with visible expansion of the maxillary bones in the face
Hypersplenism is common
Differential diagnosis
The photosensitivity differentiates CEP from other scarring,
blistering disorders of childhood, including epidermolysis bullosa
dystrophica
The cutaneous changes may resemble HEP (the
homozygous form of familial PCT) or homozygous VP

48. Investigations
 massive accumulation in all tissues of type I isomers of porphyrins, mainly uroporphyrin,
along with coproporphyrin and smaller amounts of 7‐, 6‐ and 5‐carboxylic acid porphyrins
 Red cells and urine contain large amounts of uro‐ and coproporphyrin(mainly type I) and
faeces contain increased concentrations of coproporphyrin (mainly type I)
 A plasma spectrofluorimetry peak is seen at 615–620 nm
 The absence of isocoproporphyrins and the normal level of 5‐carboxylic porphyrin excretion
in faeces distinguish CEP from HEP

49. Acquired Porphyrias
• A characteristic difference from congenital porphyrias is that there is
associated anemia in the acquired variety
CAUSES
Heavy metals : lead PBG Synthase
Toxin : hexachlorobenzene Uroporphyrin I Synthase
Malignancies HMB Synthase
chronic renal failure UPG Decarboxylase
 Lead Porphyria/Plumboporphyria is the most common. It inhibits
Ferrochelatase and ALA Dehydratase.

50. Acquired Porphyrias (cont.)
Clinical Features
Children Adults
Devolopmental defect Abdominal pain and Constipation
Drop in IQ Insomnia
Anxiety and Hyperactivity Seizures and Mental confusion
Treatment
1. Remove the precipitating toxins or drugs
2. Treat anemia and use analgesics and anticonvulsants
3. Use of Chelators: Calcium disodium EDTA, Succimer, Dimercaprol, Penicillamine

51. DIAGNOSING A CASE OF PORPHYRIA
 Lab tests are required along with typical clinical features to make a definitive diagnosis of Porphyria
 Urine , blood and stool examination for various porphyrins
 Urine test: reveals elevated levels of two substances: PBG and delta- ALA, as well as other porphyrin
The presence of porphyrin precursor in urine is detected by Ehrlich’s reagent
When urine is observed under ultraviolet light porphyrins if present, will emit strong red fluorescence
 Blood test: may show an elevation in the level of porphyrins in your blood plasma (cutaneous
porphyria)
 Stool sample test: may reveal elevated levels of some porphyrins not detected in urine samples

52.  Spectrophotometry : to test for Porphyrins & Their Precursors Coproporphyrins & Uroporphyrins
 UV fluorescence is the best technique to demonstrate porphyrins
 Use of appropriate gene probes has made possible the prenatal diagnosis of Porphyria
 HPLC analysis of urine and faeces to detect specific fluoroscence
 Measurement of RBC free and Zinc protoporphyrin

55. Diagnostic Algorithm

58. TREATMENT
Managing a case of acute attack
1. Removing the precipitating drug or toxin
2. IV infusion of haemin arginate or lyophyllised haemin
3. Narcotic analgesics for pain
4. Ondansetron
5. Low doses short-acting benzodiazepines for restlessness or insomnia
6. β-Adrenergic blocking agents for tachycardia and hypertension
7. IV 10% dextrose
8. Treatment of seizure

60. Managing cutaneous porphyria
1. Adequate sun protection
2. Oral Beta carotene
3. Venesection or phlebotomy
4. Low dose HCQ is effective for PCT
5. Vitamin D supplements

61. Preventive measures
 Avoid triggers( drugs ,toxins ,stress )
 Stop Alcohol and smoking
 Avoid fasting / dieting
 Minimise sun exposure
 Genetic testing and counselling

62. Scope of new therapy
 Liver transplantation
 Bone marrow transplantation
 Pharmacological chaperones to rescue misfolded mutant enzyme
 siRNA therapy
 Stem cell and gene therapy

63. TAKE HOME MESSAGE
 No truth in the myth : Patients of PORPHYRIA are
VAMPIRES
 Early diagnosis and treatment can provide effective
remission
 Family screening ,genetic testing and preventive measures
improve the outcome

64. DARE TO FACE THE SUN
THINK PORPHYRIA …..DON’T SUFFER PORPHYRIA