First let me try and explain condition Polycythemia.
Polycythemia is a condition with increased amount of red blood cells causing raised haemoglobin and haematocrit. It is generally treated by phlebotomy and hydroxyurea. It can be primary or secondary; inherited or due to any underlying disease.
Chuvash is a type primary Polycythemia. It is a very rare condition, originally the gene which is responsible for this hereditary condition was present in Russians. Symptoms patient may experience vertigo, shortness of breath, dizziness and hypotension. Intravascular bleeding is a fatal complication of this disease which may cause death.
Lab reports showing increased RBC, HBG, erythropoietin and mutated gene carrying the disease indicate towards the disease.