Final answer:
The blood disorder involving a deficiency of Vitamin B12 is pernicious anemia, caused by poor absorption, leading to symptoms like fatigue and neurological issues.
Step-by-step explanation:
The blood disorder that involves a deficiency of Vitamin B12 is pernicious anemia. Pernicious anemia results from the poor absorption of vitamin B12, which is essential for the production of healthy red blood cells. When the body lacks vitamin B12, it leads to the production of large, immature red blood cells known as megaloblasts, which are not efficient in carrying oxygen throughout the body. This condition can lead to a variety of symptoms including fatigue, weakness, and neurological issues. It is often seen in patients with conditions that affect the absorption of nutrients from the digestive tract, such as Crohn's disease, or in those who have had parts of their stomach or intestines surgically removed.
In contrast, sickle cell anemia is caused by a genetic mutation that leads to the production of abnormal hemoglobin, resulting in sickle-shaped red blood cells. These abnormally shaped cells can cause blockages in blood vessels, leading to pain and organ damage. Iron deficiency anemia, vitamin deficiency anemia, and diseases affecting bone marrow and stem cells are other types of anemias caused by faulty or decreased red blood cell production.