Final answer:
The disorder caused by high altitude that increases the red blood cell count is known as polycythemia, an adaptation that allows the blood to carry more oxygen in response to lower oxygen levels in these environments.
Step-by-step explanation:
The red blood cell disorder caused by life at a high altitude is called polycythemia. This condition is characterized by an elevated red blood cell (RBC) count and is often a chronic adaptation for residents in high-altitude environments. The increase in RBC count allows the blood to carry more oxygen, compensating for the lower oxygen levels in these areas.
Polycythemia can also occur in other instances such as dehydration, where reduced plasma volume leads to a relative increase in hematocrit. However, when specifically caused by high altitude, it is not a disease but rather a physiological adaptation. Polycythemia vera, on the other hand, is a serious bone marrow disease leading to the excessive production of RBCs, which can increase the viscosity of blood and pose health risks.