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Porphyria Educational Services

Vol.2 No. 16 April 16, 2000
FOCUS: Chester Porphyria

Up until the isolation of HCP type porphyria it was thought that there
were only six types of porphyria.

Then HCP was isolated about a decade ago. Since then ALA-D
type has been isolated and identified.

In the last few years various subtypes of various main types of
porphjyria have been identified. One could say, a further mutating of a given

Also in the last few years it has been possible to identify porphyria patients
having more than one type of porphyria. This happenstance is known as a "dual
variety" of types of porphyria.

Quite often one variety is inherited and the other is acquired. This would be
the case in AIP/PCT. However many people have undergone many testings and have
been proven to have a dual variety of inherited types as well such as VP/HCP.

In addition there are subsets that show up in various types of porphyria.
In AIP there is one that shows up in 14% of all porphyria patients. In normal
AIP a blood serum test will show a diminished or below normal of PBG-deamanase.
But in the subset, this 14% have a normal blood serum test level.

So these AIP patients usually have to test and retest because their blood
test levels always come out normal. Such is Chester porphyria.

Chester Porphyria is a form of Acute Intermittent Porphyria, but it does
not show up in blood or stool testing.

Another name for Chester porphyria is Dobson's complaint.

This form of porphyria gets it's second name from the Dobson family of Chester
England. Members of the Dobson family had a "strange malady" that
obviously passed down through the generationsran in the family lines.

Today approximately 14% of AIP patients have this type of porphyria.
Geneology of p[orphyria patients with this trait can trace their heritage right back to
the west coast of England and the Chester area.

The mutation wasn't discovered
until DNA tests became wide spread. DNA testing began about a decade ago.

As DNA testing is becoming more available, it is being discovered that
each family line seems to have it's own mutation. For instance in one family of 14
certain markings are all the same and the next generation has just a little more
added to the mutation.

An interesting side note here is that in the South African Variegates
porphyria patients the defect is on T28. In the royal families the porphyria defect
is located on T30.

For the future of porphyria patients, the more porphyria DNA researchers
learn about the genetic defects in the disease, the more research will realize that
each porphyria type is slightly different from one generation to the next and also
due to environmental exposures which may indeed make an important impact
in theincrease of acute porphyrias.