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A Guide To Porphyria

What about surgery or pregnancy?
Although there may be a risk of precipitating an acute attack of porphyria when a patient requires surgery, this problem can be either avoided or controlled by the application of preventative measures and the use of appropriate drugs and anaesthetic agents by knowledgeable physicians. However the entire medical team must be conversant with this disease. The risk of problems arising during pregnancy is also relatively minor and the symptoms can be easily managed. Every patient with porphyria should wear or carry with them some type of identification such as a Medic-Alert bracelet indicating the fact that they may be at risk for porphyria. Rather than concealing the fact, they should also ensure that their close family and friends know about their condition. The individual patient should make a point of becoming as knowledgeable as possible about their disease and their health.

What about my children?
Since porphyria is caused by a defective gene, it means that the children can be affected if one of the parents has porphyria. The inheritance of this gene can be classified as either dominant, in which case there is a 1 in 2 chance that the child will develop the disease, or as recessive in which case it will be very unlikely for the offspring to develop the problem. Although most types of porphyria are associated with a dominant inheritance pattern, the majority of the carriers of these abnormal genes will have latent disease and never develop symptoms and not be aware of this problem throughout their entire lives. Genetic counseling is available but most patients prefer to go about their lives in a normal fashion and deal with their family planning in their own personal fashion. The screening tests for porphyria may not become positive until after puberty but some clinics recommend periodic testing every few years starting at age 10 for children at risk of this disease. Many young patients do not bother with this testing since the test results are often unreliable and prefer to adopt a 'wait and see' attitude, while still following the appropriate preventative protocols.

Future prospects
Considerable progress has been made in the understanding of the genetic defects giving rise to the clinical and biochemical features of porphyria. The genes have been identified and decoded and mouse models of the disease have been made by genetic engineering. This should enable scientists to assess new treatments and allow pharmaceutical companies to test new drugs for their porphyrogenic properties. However these research advances have yet to be transferred into significant changes in the standard bedside medical practices and laboratory diagnostic techniques. It can be anticipated that this will change reasonably soon. Some very sick patients may benefit by the newer techniques of bone marrow and liver transplantation. However specific gene therapy is still a long ways away.

One major advance that is interesting, although it does not bear directly on the disease of porphyria is the development of photodynamic therapy. It has been found that some types of cancer cells will concentrate porphyrin compounds at a much higher concentration than the surrounding normal cells. These tumour cells containing the porphyrin photosensitizers will absorb the energy from radiant light and concentrate it to a much greater degree than that seen in most cases of porphyria. This abnormal increase in intracellular energy will bring about the formation of a molecule called singlet oxygen which can be toxic and will selectively kill the malignant cells. This concept has already been successfully applied to the treatment of some cancers of the mouth, pharynx and esophagus. The same approach has been tried in agriculture in the development of biodegradable herbicides and pesticides.