Question: How many people are affected by von Hippel-Lindau syndrome ?
Answer: The incidence of von Hippel-Lindau syndrome is estimated to be 1 in 36,000 individuals.
Source: GHR

Question: Is von Hippel-Lindau syndrome inherited ?
Answer: Mutations in the VHL gene are inherited in an autosomal dominant pattern, which means that one copy of the altered gene in each cell is sufficient to increase the risk of developing tumors and cysts. Most people with von Hippel-Lindau syndrome inherit an altered copy of the gene from an affected parent. In about 20 percent of cases, however, the altered gene is the result of a new mutation that occurred during the formation of reproductive cells (eggs or sperm) or very early in development. Unlike most autosomal dominant conditions, in which one altered copy of a gene in each cell is sufficient to cause the disorder, two copies of the VHL gene must be altered to trigger tumor and cyst formation in von Hippel-Lindau syndrome. A mutation in the second copy of the VHL gene occurs during a person's lifetime in certain cells within organs such as the brain, retina, and kidneys. Cells with two altered copies of this gene make no functional VHL protein, which allows tumors and cysts to develop. Almost everyone who inherits one VHL mutation will eventually acquire a mutation in the second copy of the gene in some cells, leading to the features of von Hippel-Lindau syndrome.
Source: GHR