The Arctic and Antarctic Circles are located at Â±66.5 degrees latitude. Note that 66.5 + 23.5 equals 90 degrees. This means that on December 21, when the Sun is directly over the Tropic of Capricorn at noon, it will not be visible from the Arctic Circle.
It's not clear what causes hairy cell leukemia. Doctors know that cancer occurs when cells develop errors in their DNA. In the case of hairy cell leukemia, mutations in the DNA cause your bone marrow stem cells to create too many white blood cells that don't work properly. Doctors don't know what causes the DNA mutations that lead to hairy cell leukemia. Symptoms.
Hairy cell leukemia (HCL), a slow-growing lymphocytic cancer, accounts for about 2 percent of all leukemias. Like many other types of cancer, chronic leukemias become more common with age. The average age of patients with chronic lymphocytic leukemia (CLL) is roughly 70 years, and the average age of chronic myelogenous leukemia (CML) patients is 40 to 50 years old. By contrast, acute lymphocytic leukemia (ALL) is largely a pediatric (childhood) disease and usually occurs in children younger than 10 years of age. Worldwide, leukemia generally affects men more often than women. In Western countries, the male:female ratio is highest in CLL patients.