Chuvash erythrocytosis is a rare genetic disorder caused by a mutation in the VHL gene. This gene is responsible for producing a protein that helps regulate the production of red blood cells. When the VHL gene is mutated, it causes an overproduction of red blood cells, leading to an increase in the number of red blood cells in the body. This can lead to a variety of symptoms, including fatigue, headaches, dizziness, and shortness of breath. Other potential causes of Chuvash erythrocytosis include environmental factors, such as exposure to certain chemicals, and lifestyle factors, such as smoking or drinking alcohol.