A blood type (also known as a blood group) is  a classification of blood, based on the presence and absence of antibodies and inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system. Some of these antigens are also present on the surface of other types of cells of various tissues. Several of these red blood cell surface antigens can stem from one allele (or an alternative version of a gene) and collectively form a blood group system.Blood types are inherited and represent contributions from both parents of an individual. As of 2021, a total of 43 human blood group systems are recognized by the International Society of Blood Transfusion (ISBT). The two most important blood group systems are ABO and Rh; they determine someones blood type (A, B, AB, and O, with + or − denoting RhD status) for suitability in blood transfusion. Blood group systems
A complete blood type would describe each of the 43 blood groups, and an individuals blood type is one of many possible combinations of blood-group antigens. Almost always, an individual has the same blood group for life, but very rarely an individuals blood type changes through addition or suppression of an antigen in infection, malignancy, or autoimmune disease. Another more common cause of blood type change is a bone marrow transplant. Bone-marrow transplants are performed for many leukemias and lymphomas, among other diseases.
Porokeratotic eccrine ostial and dermal duct nevus is a skin lesion that resembles a comedonal nevus, but it occurs on the palms and soles where pilosebaceous follicles are normally absent. It is probably transmitted by paradominant transmission. See also
Prominent inferior labial artery
List of cutaneous conditions


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