Pernicious anemia, also known as vitamin B12 deficiency anemia, is a disease in which there are not enough red blood cells due to a lack of vitamin B12. The most common initial symptom is feeling tired. Other symptoms may include shortness of breath, pale skin, chest pain, numbness in the hands and feet, poor balance, a smooth, red tongue, poor reflexes, and confusion. If treatment is not provided, some of these problems may become permanent.