2. Introduction
• Hemoglobin is made up of heme and globin
parts
• A defect in the production of either leads to
abnormal production and function.
• These abnormalities may result from DNA
defect, abnormal chain production or enzyme
defects.
3. Intro….
• Abnormalities in haemoglobin chain and DNA
are preferentially studied as anaemias.
• The defects associated with heme synthesis
and especially those relating to enzymes in
the production pathway are porphyrias.
4. Porphyrias
• These are pathogical defects associated with
partial defects in heme synthesis enzymes.
• These enzymes include among others,
– Ferrochelatase
– Uroporphyrinogen (III) cosynthase
– δ-aminolevulinic acid dehydratase
• The defects lead to accumulation of porphyrins
which are not useful but are also toxic
5. • Porphyrias are either inherited or acquired
defects.
• They can also be classified as follows
– Manifestations
• Photosensitive or neurological
– According to principal site of enzyme expression
• Hepatic or erythropoietic
• These classifications do however overlap
6. Congenital erythropoietic Porphyrias
• This is a rare condition inherited as a
congenital autosomal recessive condition.
• The enzyme deficiency involved is
uroporphyrinogen (III) synthase.
• haemolytic anaemia which is photosensitive
develops at birth
• Accumulation of uroporphyrinogen and
coproporphyrin
7. Erythropoietic protoporphyria
• This is an autosomal dominant disorder and is
relatively common compared to CEP.
• Ferrochelatase deficiency is the cause of this
disorder.
• Excessive accumulation of protoporphyrin in in
RBCs and excretion in stool
• This is a mild condition, usually no hematologic
manifestations
• however, some may develop porphyrin rich
gallstones
