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Porphyria Educational Services

PORPHYRIA EDUCATIONAL SERVICES BULLETIN
Vol. 2 No. 17 April 23, 2000
FOCUS: Delta-Aminolevulinic Acid Dehydratas Deficiency [ALA-D] Porphyria


ALA-D porphyria is an autosomal recessive disorder. The ALA-D is now the
rarest porphyria. ALA-D results from a deficiency of ALA dehydratase in the heme
pathway.


There are several different mutations in the gene for ALA dehydratase
that have been charted in non-related patients. The ALA-D disease was
first described in Germany . However the disease probably occurs in
all countries.

The ALA-D Icauses neurologic symptoms and sometimes anemia.
ALA-D's symptomology resembles those of the acute porphyrias but
can also include hemolysis and anemia.

Symptoms of ALA-D may begin in infancy or adulthood. In ALA-D the urinary ALA
and coproporphyrin III and erythrocyte zinc protoporphyrin are markedly increased.

In ALA-D and other disorders in which ALA accumulates, excess ALA may be
metabolized to coproporphyrin III in tissues other than the tissue of origin of the excess ALA.

In ALA-D the fecal porphyrin excretion is normal or marginally elevated.
Patients with ALA-dehydratase-deficient porphyria demonstrate little activity of ALA
dehydratase in erythrocytes or in nonerythroid cells. Parents of an ALA-D
porphyric show about 50% enzyme activity.

The diagnosis of ALA-D is made by finding an excess of ALA and coproporphyrin
in urine and a deficiency of ALA dehydratase in erythrocytes. One thing that is important
to remember is that other causes of this enzyme deficiency, such as lead poisoning
and tyrosinemia, must be excluded.

These conditions can also manifest with symptoms such as
abdominal pain, ileus, and motor neuropathy that are strikingly similar to
those of the acute porphyrias.