The new "porphyria gene"
Mutation causing "vampire disease" found
Sergey Vasiliev, Naked Science
Hereditary porphyria has been linked to a protein involved in the formation of other proteins – mutations in its gene disrupt hemoglobin synthesis and cause "vampire" photophobia.
A patient with porphyria (photo from Wikipedia)
It is believed that some legends about vampires were inspired by cases of a rare but actually occurring hereditary disease, erythropoietic porphyria. In people suffering from various forms of this disease, hemoglobin synthesis is disrupted, which leads to anemia and the accumulation of intermediates in the blood, protoporphyrins. Under the influence of ultraviolet radiation, they turn into porphyrins, which damage skin cells, causing severe inflammation, ulcers, soft tissue deformities. It is not surprising that patients carefully avoid sunlight and are forced to resort to blood transfusions every now and then.
The disease can take different forms, depending on which stage of hemoglobin production is blocked, and not all of them have been linked to mutations in specific genes. Only recently, American doctors discovered a disorder in the ClpX gene leading to the development of "vampire" erythropoietic porphyria (Erythropoietic Protoporphyria, EPP). The article by Dr. Barry Paw and his colleagues from Boston Children's Hospital is published by PNAS magazine.
It is worth saying that hemoglobin is a complex molecule containing a protein part and a pigment group (heme) – a protoporphyrin compound with a coordinated iron atom. This final stage of metal addition catalyzes the ferrochelatase enzyme, and, as a rule, the development of EPR is associated with a violation in the gene of this enzyme (FECH). However, in some cases, there is nothing wrong with the FECH gene in patients, which puts scientists at a dead end. Only a new study by Boston doctors has shown that a completely different gene – ClpX, which is involved in a number of intracellular processes associated with protein synthesis, can be the culprit of EPR.
Scientists note that for the synthesis of heme and hemoglobin, it is enough for the body to have at least one normal copy of the ClpX gene – while the blood will be able to carry oxygen and carbon dioxide, supporting life. However, the final stage of production will remain the slowest and will not be able to keep up with the previous steps, forcing red blood cells to accumulate an intermediate product, protoporphyrin IX. It is he who, under the influence of light, causes damage to cells, causing severe "vampire" disease.
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08.09.2017