Haemoglobin abnormalities porphyrias.pptx

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1. Haemoglobin abnormalities

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 stooj This is a mild condition, usually no hematologic manifestations however, some may develop porphyrin rich gallstones