Pernicious anemia is a type of vitamin B12 deficiency anemia, a disease in which not enough red blood cells are produced due to the malabsorption of vitamin B12. Malabsorption in pernicious anemia results from the lack or loss of intrinsic factor needed for the absorption of vitamin B12. Anemia is defined as a condition in which the blood has a lower than normal amount of red blood cells or hemoglobin. The disease may come on slowly and insidiously.The most common initial symptoms are tiredness, and weakness. Other signs and symptoms of anemia include breathlessness, dizziness, a sore red tongue, lightheadedness, headaches, poor ability to exercise, cold hands and feet, low blood pressure, pale or yellow skin, chest pain, and an irregular heartbeat. The digestive tract may also be disturbed giving symptoms that can include nausea and vomiting, heartburn, upset stomach and loss of appetite. Pernicious anemia can cause osteoporosis and may lead to bone fractures. Symptoms of severe vitamin B12 deficiency can include tingling or numbness in the hands and feet, memory problems, blurred vision, unsteady walking, poor balance, muscle weakness, impaired sense of taste and smell, poor reflexes, clumsiness, depression, and confusion. Without treatment, some of these problems may become permanent.Pernicious anemia occurs due to an autoimmune response that produces antibodies that attack the parietal cells in the stomach lining and prevents them from creating intrinsic factor.
Progressive osseous heteroplasia is a cutaneous condition characterized by cutaneous or subcutaneous ossification.According to the Progressive Osseous Heteroplasia Association:

Progressive Osseous Heteroplasia (POH) is a rare genetic condition in which the body makes extra bone in locations where bone should not form. Extra bone develops inside skin, subcutaneous tissue (fat tissue beneath the skin), muscles, tendons, and ligaments. This ”out of place extra bone formation” is commonly referred to as heterotopic ossification. In people with POH, nodules and lace-like webs of extra bone extend from the skin into the subcutaneous fat and deep connective tissues, and may cross joints. Extra bone formation near the joints may lead to stiffness, locking, and permanent immobility.”
It is associated with GNAS.A telltale symptom of POH is osteoma cutis under the skin of a newborn. It was discovered in 1994 by physician Frederick Kaplan. Diagnosis
Patients with POH have a distinctly different manifestation of symptoms than those with fibrodysplasia ossificans progressiva (FOP), though heterotopic ossification appears in both diseases. They lack the congenital abnormality of the big toe that is a diagnostic feature for FOP. People with POH also have ossification of the skin during infancy, which does not occur in FOP. Also, the pattern of ossification differs in POH, spreading in an intramembranous fashion rather than endochondral. See also
Fibrodysplasia ossificans progressiva
Punctate porokeratosis
List of cutaneous conditions
Pseudopseudohypoparathyroidism

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