Von-Hippel Lindau or VHL is a genetic disease that affects people of all ethnicities and is characterized by tumor development in the CNS, kidneys, adrenal glands and pancreas.
Okay, the VHL gene is a tumor suppressor gene on the short arm of chromosome 3.
It codes for proteins that degrade hypoxia-inducible transcription factor, or HIF. HIF upregulates genes that code for platelet-derived and vascular endothelial growth factors, both of which promote new blood vessel formation and cell growth.
In VHL disease, this tumor suppressor gene is mutated which increases HIF, PDGF, VEGF, and ultimately the risk of tumor formation.
VHL disease is about as common as Huntington Disease, occurring in 1 in 36,000 people.
It is inherited in an autosomal dominant pattern, meaning that a VHL patient has a 50% chance of passing it on to each kid they have.
20% of VHL patients have a de novo or new mutation, meaning they are the first VHL patient in their family.
Alright, the most common tumor type in VHL is hemangioblastoma, a benign blood vessel tumor occurring in about 60% of VHL patients.
In the central nervous system, these can occur in the retina, brain, and spinal cord.
In the eyes, it can cause blindness by detaching the retina.
In the brain and spinal cord, a tumor or the accompanying cyst causes problems when it pushes against surrounding tissue.
For example, if the tumor is in the cerebellum, it can cause ataxia, or the loss of balance.
If it blocks the flow of cerebrospinal fluid, intracranial pressure can rise causing headaches, nausea, and vomiting.
Less common are benign cysts and cyst-like tumors called cystadenomas.
The most concerning, occurring in ~25% of VHL patients, is the endolymphatic sac tumor of the inner ear which can cause deafness.