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Porphyrias & Congenital Dyserythropoietic Anemia

Terms in this set (12)

Porphyria
• An acquired or inherited condition in which one or more of the enzymes involved in the heme synthesis pathway is defected
• Results in an accumulation of porphyrin intermediates and anemia
• In porphyrias, the porphyrin intermediates accumulate due to blocked, deficient, or abnormal enzymes that usually progress the synthesis sequence
Congenital Erythropoietic Porphyria
• Autosomal recessive
• Cause: decreased level of uroporphyrinogen III cosynthetase
• Increased build up of ALA, porphrinogen, uroporphyrinogen I, and coproporphyrinogen I, which turn the urine a red color. The last two are also found in the feces.
• Results: red pigmented urine, erythrodontia, severe cutaneous sensitivity (emits fluorescence), hemolytic anemia, and splenomegaly
• RBC source
Erythrohepatic Protoporphyria
• Autosomal dominant
• Cause: abnormal ferrochelatase
• Ferrochelatase incorporates iron into the protoporphyrin to produce heme
• Increased Protoporphyrin IX in the feces; urine is normal
• Clinical features: mild skin photosensitivity, hepatic & erythrocytic abnormalities (dysfunctional liver, anemia)
Acute Intermittent Porphyria
• Autosomal dominant
• The most common type of inherited porphyriaa*
• Cause: deficient uroporphrinogen I synthetasee* (the enzyme that allows the offshoot to proceed)
• Increased urinary ALA and porphobilinogen
• Normal fecal sample
• Increased alkaline phosphate and bilirubin
• Clinical features: vomiting, abdominal pain, psychosis, hypertension, leukocytosis, peripheral neuritis, constipation, and fever
Hereditary Coproporphyria
• Autosomal dominant
• Cause: deficient coproporphyrinogen oxidative decarboxylasee*, which converts corprophyrinogen III into Protoporphyrin IX
• Increased coproporphyrinogen III in the feces and urine--causes the feces to be fluorescent
• Clinical features: symptoms range from asymptomatic to mild neurology, abdominal pain, and psychiatric symptoms
Variegate Porphyria
• Autosomal dominant
• Cause: deficient protoporphrinogen oxidase
• Urine findings: Delta ALA, porphobilinogen
• Fecal findings: protoporphyrin, coproporphyrin
• Clinical findings: abdominal pain, leukocytosis, psychosis, and cutaneous lesions
Cutaneous Hepatic Porphyria (Porphyria Cutanea tarda)
• Two forms: inherited and acquired
1. Inherited
• Autosomal dominant
• Cause: uroporphyrinogen III decarboxylasee*
• Urine: uroporphyrin III and uroporphyrin I
• Feces: protoporphyrin, coproporphyrin
2. Acquired porphyria (porphyrinuria)
• Cause: liver disease, alcoholic cirrhosis, estrogen therapy, hexachlorobezene exposure
Congenital Dyserythropoietic Anemia (CDA 1)
• A congenital anemia due to dyserythropoiesis (abnormal RBC development) and ineffective erythropoiesis (RBCs not leaving the BM, dying there)
• Hemolytic in nature
• There are four types: CDA 1, CDA 2, CDA 3, and CDA 4
CDA 1
• Autosomal recessive
• Megaloblastic changes
• Macrocytic anemia with poikilocytosis and anisocytosis
• Bridges between erythroblasts
• Multi-lobed erythroblasts
• Apparent at birth
CDA 2
• Autosomal recessive
• No megaloblastic changes
• Hereditary, multinuclear erythroblasts
• Sensitive (susceptible) to IgI
• Due to IgI sensitivity, will test positively on HAM's test/Acidified Serum Test
• Negative sugar water test
• Normocytic normochromic anemia
CDA 3
• Autosomal dominant
• No megaloblastic changes
• Hereditary, multinuclear erythroblasts
• Negative HAM's test/Acidified Serum Test
CDA 4
• Autosomal recessive
• Similar to CDA 2, but..
(a). Differ in cellular ultrastructure
(b). No serologic sensitivity (abnormality)
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