Zbar says that patients can make rational plans for their futures once they have genetic information. He tells the story of one woman who, like many people with VHL, had had numerous tumors in her kidney and was left with only one kidney that could function. Many of the woman's relatives had been tested for the VHL gene, which is how she knew that one son had inherited the VHL gene and the other had not. People have an appreciation for what VHL does and doesn't do to them. When a person has VHL, the tumor suppressor gene is damaged and cannot fulfill its normal function.
Cells multiply out of control and tumors develop.
Cells of people who inherit VHL contain one altered copy of the VHL tumor suppressor gene and one normal copy of that gene. But, if the second allele is altered, tumor suppression ends in that cell and the disease begins. Not only do the hits to the VHL genes differ from individual to individual, but so do the signs and symptoms of the disease. The situation is quite complicated. On the one hand, there is evidence that specific mutations are associated with the development of distinctive signs and symptoms.