Most cases result from the lack of the gastic protein known as intrinsic factor, without which vitamin b12 cannot be aborbed.
Symptoms may include; weakness, fatigue, an upset stomach, an abnormally rapid heartbeat, and/or chest pains.
Pernicious anemia is thought to be n autoimmune disorder, and certain people may have a genetic predisposition to this disorder.
Pernicious anemia typically does not appear before the age of 30. The onset of the disease is slow and may span decades.
Usually born with it but there is also a juvenile form of the disease.
When the disease goes undiagnosed and untreated for a long period of time, it may lead to neurological complications.
Nerve cells and blood cells need vitamin b12 to function properly.
(http://www.webmd.com/a-to-z-guides/anemia-pernicious )
Because of decreased oxygen-carrying capacity of the blood anemia usually causes tireness and shortness of breath. Pale skin.
Feelings of numbness, tingling, weakness, lack of coordination, clumsiness, impaired memory, and personality changes can all occur.
Both sides of the body are usually affected, and the legs are typically more affected than the arms.
A severe deficiency can result in more serious neurological symptoms, including severe weakness, spasticity, paraplegia, and fecal ad urinary incontinence. http://www.buzzle.com/articles/pernicious-anemia.html http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001595/
http://www.medicinenet.com/pernicious_anemia/article.htm