A blood type (also called a blood group) is a classification of blood based on the presence or absence of 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 very closely linked genes) and collectively form a blood group system. Blood types are inherited and represent contributions from both parents. A total of 30 human blood group systems are now recognized by the International Society of Blood Transfusion (ISBT).
Many pregnant women carry a fetus with a blood type different from their own, and the mother can form antibodies against fetal RBCs. Sometimes these maternal antibodies are IgG, a small immunoglobulin, which can cross the placenta and cause hemolysis of fetal RBCs, which in turn can lead to hemolytic disease of the newborn called erythroblastosis fetalis, an illness of low fetal blood counts that ranges from mild to severe. Sometimes it can be lethal for fetus called hydrops fetalis.
Read more about Blood Type: Blood Group Systems, Blood Group Genotyping, History, Society and Culture
Famous quotes containing the words blood and/or type:
“His [O.J. Simpson’s] supporters lined the freeway to cheer him on Friday and commentators talked about his tragedy. Did those people see the photographs of the crime scene and the great blackening pools of blood seeping into the sidewalk? Did battered women watch all this on television and realize more vividly than ever before that their lives were cheap and their pain inconsequential?”
—Anna Quindlen (b. 1952)
“This immediate dependence of language upon nature, this conversion of an outward phenomenon into a type of somewhat in human life, never loses its power to affect us. It is this which gives that piquancy to the conversation of a strong-natured farmer or backwoodsman, which all men relish.”
—Ralph Waldo Emerson (1803–1882)