The Effects of the Mutation and Von Hippel-Lindau Symptoms
Because the VCB-CLU2 complex under normal conditions has an effect on a number of different proteins, alterations of the VHL gene can trigger several different conditions, whose timing and severity differ from individual to individual.
The lack of control in the formation of blood vessels can cause the creation of hemangioblastomas, which are non-cancerous tumors made of “knots" of blood vessels. Even though these growths are benign, when hemangioblastomas develop in the central nervous system they can exert pressure on nerves, causing headaches, loss of coordination or vomiting. At times, the uncontrolled growth of blood vessels can develop in the retina and may even cause loss of vision. In such cases, the growths are called retinal angiomas.
It has also been observed that alterations in the VHL gene can be the cause of a blood disorder called Chuvash polycythemia, also known as congenital polycythemia. Characteristics of this disease include the excessive formation of red blood cells, which may cause excessive bleeding, formation of blood clots or even strokes.
In other cases, VHL can cause tumors in the kidneys, called clear cell renal cell carcinomas, or in the adrenal glands, called pheochromocytomas, or pheos. Pheos are very rarely cancerous, and, when detected early, they are not difficult to treat. Nevertheless, these tumors can still be lethal to an individual if they are left untreated. In fact, the presence of pheos causes an uncontrolled production of noradrenalin and adrenaline, which are hormones that the body uses during stressful situations. The secretion of these hormones causes a serious rise in blood pressure that could lead to heart attack or a stroke.