Blood Types Chart | Blood Group Information | American Red Cross Printable Version Blood Types Although all blood is made of the same basic elements, not all blood is alike. In fact, there are eight different common blood types, which are determined by the presence or absence of certain antigens – substances that can trigger an immune response if they are foreign to the body. Since some antigens can trigger a patient's immune system to attack the transfused blood, safe blood transfusions depend on careful blood typing and cross-matching. The ABO Blood Group System There are four major blood groups determined by the presence or absence of two antigens – A and B – on the surface of red blood cells: Group A – has only the A antigen on red cells (and B antibody in the plasma) Group B – has only the B antigen on red cells (and A antibody in the plasma) Group AB – has both A and B antigens on red cells (but neither A nor B antibody in the plasma) Group O – has neither A nor B antigens on red cells (but both A and B antibody are in the plasma) There are very specific ways in which blood types must be matched for a safe transfusion.

See the chart below: In addition to the A and B antigens, there is a third antigen called the Rh factor, which can be either present (+) or absent ( – ). In general, Rh negative blood is given to Rh-negative patients, and Rh positive blood or Rh negative blood may be given to Rh positive patients. The universal red cell donor has Type O negative blood type. The universal plasma donor has Type AB blood type. Blood Types and the Population O positive is the most common blood type. Not all ethnic groups have the same mix of these blood types. Hispanic people, for example, have a relatively high number of O’s, while Asian people have a relatively high number of B’s. The mix of the different blood types in the U.S. population is: Blood groups - NHS Choices Blood groups Blood groups Introduction There are four main blood groups (types of blood): A, B, AB and O. Your blood group is determined by the genes you inherit from your parents. Each group can be either RhD positive or RhD negative, which means your blood group can be one of the eight types shown below (see the Rh system ). What is blood?

Your body carries around four to six litres (7 to 10.5 pints) of blood. Blood is made up of red blood cells, white blood cells and platelets in a liquid called plasma. Plasma is about 90% water, but also contains proteins, nutrients, hormones and waste products. Blood is made up of about 60% plasma and 40% blood cells. Each type of blood cell has a specific role to play: red blood cells carry oxygen around the body and remove carbon dioxide and other waste products; they give blood its red colour white blood cells are part of the immune system (the body's natural defence mechanism) and help fight infection platelets help the blood clot (thicken) to stop bleeding Antigens and antibodies Your blood group is identified by antigens and antibodies in the blood. Antibodies are part of your body's natural defences against invading substances such as germs. Antigens are protein molecules found on the surface of red blood cells. Antibodies are proteins found in plasma. Antibodies recognise anything foreign in your body and alert your immune system to destroy it.

The ABO system There are four main blood groups defined by the ABO system: blood group A has A antigens on the red blood cells with anti-B antibodies in the plasma blood group B has B antigens with anti-A antibodies in the plasma blood group O has no antigens, but both anti-A and anti-B antibodies in the plasma blood group AB has both A and B antigens, but no antibodies Almost half (48%) of the UK population has blood group O, making this the most common blood group. Receiving blood from the wrong ABO group can be life threatening. For example, the anti-A antibodies in a recipient with group B blood will attack the group A cells if transfused to them. This is why group A blood must never be given to a group B person. As group O red blood cells don't have any A or B antigens, it can safely be given to any other group. Which is the most common blood group in humans? - Quora Quora Group O is the most common in all races. But from there, it varies a great deal % wise as to which blood groups predominate. AB tends to be the lowest. Remember that your are dealing with genetics and statistics!

351 Views · View Upvotes · Answer requested by Group O has been found to be quite common in the world,with a greater proportion having O positive type. An example can be found in the fact that almost 48% of the population in UK has this blood group. 102 Views · View Upvotes · Answer requested by Robert Frost , works at NASA As far as I can recall, I was never discouraged by anyone from drinking coffee while living on board the International Space Station (ISS). For me, morning coffee was one of those wonderful psychological benefits, reminding me of life here on Earth. My coffee intake was limited to "2 cups" per day. I say 2 cups, which is actually 2 bags of coffee on ISS. While typically calling for 8-10 oun... Female Health , General Health Blood is the fluid of life, without blood the human body would stop working. As the heart pumps it forces blood through a network of tube-like blood vessels which branch out throughout every part of the body. There are three main types of blood vessels: Arteries - the largest and thickest of the blood vessels. These vessels carry blood from the heart to all the cells in the body.

The largest artery of the body is called the aorta, the aorta originates from the heart and then branches out into smaller arteries , the smallest arteries are called arterioles, which branch out until they become tiny capillaries. Capillaries- the smallest blood vessels, it is in the capillaries that the exchange of oxygen and carbon dioxide take place. Capillaries are so small that red blood cells can only travel through them in single file. Veins- similar to arteries but because they transport blood at a lower pressure they are not as strong as arteries . Very small veins called venules receive blood from the capillaries, after the exchange of oxygen and carbon dioxide has taken place. The venules branch into larger veins, which eventually carry the blood to the largest vein in the body, known as the vena cava, where the blood is then transported to the heart. The heart pumps blood through the arteries , capillaries and veins, carrying nutrients from digested food and oxygen to every cell in the body. The blood also removes carbon dioxide and waste products. The adult human body contains approximately 5 litres of blood and accounts for approximately 7-8% of our total body weight. Where is blood made ?

Blood cells are produced in the bone marrow, which is a soft spongy material that fills up the cavities of the bones. All of the different types of blood cells are made in the bone marrow. In a healthy individual millions of red and white cells are produced and formed daily in the bone marrow. What is blood made up of? Everyone’s blood is made up of a fluid called plasma and three types of blood cells , red, white and platelets. Nearly half the blood, approximately 45% is made up of the various blood cells the remaining 55% is plasma. Carry on reading to learn more about each of these. Plasma Plasma is the liquid portion of the blood, it is a clear, yellowish (straw colour) fluid and is mostly made up of water(90%) and salts. Blood cells travel through the body in plasma. In addition to carrying blood cells throughout the body, plasma also carries hormones , nutrients, proteins and chemicals such as iron. Red blood cells Red blood cells are also known as erythrocytes, their primary function is to carry oxygen from the lungs to the cells all around the body.

They do this through haemoglobin, an iron containing protein that actually carries the oxygen and gives blood its red colour. The blood contains more red blood cells than any other type of cell. In a single drop of blood there are millions of red blood cells . Besides carrying oxygen, red blood cells help to remove carbon dioxide from the body. White blood cells White blood cells are also know as leukocytes and their main function is to help our body fight infection. They circulate around the body so that they can be transported to an area where an infection develops. A drop of blood can contain anywhere from 7,000 to 25,000 white blood cells at a time. When the number of white blood cells in the blood increase, this is a sign of infection somewhere in your body, for example a person with leukaemia could have as many as 50,000 white blood cells in a drop of blood.

There are 5 different types of white blood cells produced by the bone marrow, the main two are called, neutrophils, the most numerous of the white blood cells and one of the body’s main defences against bacteria and lymphocytes , the second most numerous of the white blood cells , lymphocytes are involved in making antibodies as part of the immune response. Platelets Platelets also known as thrombocytes are the smallest of the blood cells . Platelets are irregularly shaped, colourless bodies that are present in blood, it is their sticky surface, along with other substances that forms clots to stop bleeding. Without them we would bleed to death. When bleeding from a wound suddenly occurs, the platelets gather at the wound and attempt to block the blood flow. A clot begins to form when the blood is exposed to air. When we get a scab over a cut that is an external blood clot, when we have a bruise that is the result of an internal blood clot. Both scabs and bruises are clots that lead to healing.

However, some clots can be dangerous, as in deep vein thrombosis (DVT) or if a blood clot forms inside a blood vessel it can block the flow of blood and so cut off supply of oxygen. A stroke is the result of a clot in an artery of the brain. What are the different blood groups? In 1901, scientist Karl Landsteiner reported that blood could be classified into blood ‘types’. There are 4 main blood groups A, B, AB and O, of which group O is the most common (47% of population). The blood type is determined by proteins called antigens found on the surface of red blood cells . If you have the antigen A on the red blood cells then you have got type A blood. When B antigen is present, you have type B blood, when both A and B are present, you have type AB blood. When neither are present you have type O blood. Another blood group system involves Rhesus factors. The name Rhesus comes from the Rhesus monkeys in which the protein was first discovered. Rhesus factor D, the most important, is found in the blood of 85% of people, they are known as Rhesus positive.

The remaining 15% are Rhesus negative. So people can be classified according to both systems, for example AB positive or O negative. The Rhesus factor is important during pregnancy, a baby’s life can be endangered if it inherits a Rhesus positive blood type from its father while the mother is Rhesus negative. This is because the mother can form antibodies against the baby’s blood. Here is a list of the blood types and their frequency in the UK population : O Rh (D) Positive AB Rh (D) Negative 0.5% We sell a test on this website which helps identify what blood group you are, for more information or to buy click here . Blood donations and transfusions Blood grouping is essential for safe blood transfusions. A patient must receive a blood type that is compatible with their own blood type. If the blood types are not compatible, red blood cells will clump together, making clots that can block vessels and cause death. In general a person with type A blood can donate to a person with type A or AB. A person with type B blood can donate to a person with type B or AB.

A person with type AB blood can only donate to a person with AB only and someone with O type blood can donate to anyone. This is because type O blood has no antigen on its surface and is often called a universal donor. Blood type AB is the universal recipient as they can receive red blood cells of any ABO type. In an emergency if there is no time for blood grouping the person in need of a transfusion would be given type O blood. In general anyone aged between 17 and 70 who weighs at least 7 stone 12lbs and is in good health can give blood. Here are a few examples of people who are unable to give blood : If you are pregnant Please visit the UK blood service website for more information on who can and can’t give blood : What can go wrong with blood? Disorders can affect any of the blood’s components, here are a few of the ones you would have heard of: Anaemia is the most common disorder of the blood. Leukaemia is another condition that affects the blood. HIV is a virus that attacks the white blood cells called lymphocytes.

There is also a rare group of disorders where abnormally prolonged or excessive bleeding may occur anywhere in the body after injury or even without injury. One well known, but luckily rare example of this is haemophilia, an inherited condition in which even the smallest injury can cause fatal internal or external bleeding. How do I maintain healthy blood? Blood like every part of the body needs good nutrition so a healthy balanced diet with plenty of fruit and vegetables will help to maintain healthy blood. What's the Most Common Blood Type? | Blood Type Percentages What's the Most Common Blood Type? By Fred Cicetti | July 13, 2012 12:53pm ET MORE Credit: Blood bags via Shutterstock "The Healthy Geezer" answers questions about health and aging in his weekly column. Question: What is the most common blood type? Answer: The approximate distribution of blood types in the U.S. population is as follows: O-positive: 38 percent AB-positive: 3 percent AB-negative: 1 percent It's important to note that the blood type distribution may be different for specific racial and ethnic groups. Type O-negative blood is called the universal donor type because it is compatible with any blood type.

Type AB-positive blood is called the universal recipient type because a person who has it can receive blood of any type . People over age 69 receive half of all transfusions of whole blood and red blood cells, according to the National Blood Data Resource Center (NBDRC). With an aging population and advances in medical treatments requiring blood transfusions, the demand for blood is increasing . On any given day, an average of 38,000 units of red blood cells are needed. If you would like to read more columns, you can get a copy of "How to be a Healthy Geezer" at . All rights reserved © 2012 by Fred Cicetti More from the Healthy Geezer: Editor's Recommendations Modern Human Variation: Distribution of Blood Types Distribution of Blood Types Blood provides an ideal opportunity for the study of human variation without cultural prejudice. It can be easily classified for many different genetically inherited blood typing systems. Also significant is the fact that we rarely take blood types into consideration in selecting mates. In addition, few people know their own type today and no one did prior to 1900. As a result, differences in blood type frequencies around the world are most likely due to other factors than social discrimination.

Contemporary Japan is somewhat of an exception since there are popular Japanese stereotypes about people with different blood types. This could affect choice in marriage partners for some Japanese. All human populations share the same 29 known blood systems, although they differ in the frequencies of specific types. Given the evolutionary closeness of apes and monkeys to our species, it is not surprising that some of them share a number of blood typing systems with us as well. When we donate blood or have surgery, a small sample is usually taken in advance for at least ABO and Rh systems typing. If you are O+, the O is your ABO type and the + is your Rh type. It is possible to be A, B, AB, or O as well as Rh+ or Rh- . You inherited your blood types from your parents and the environment in which you live cannot change them. ABO Blood Type System We have learned a good deal about how common each of the ABO blood types is around the world. It is quite clear that the distribution patterns are complex. Both clinal and discontinuous distributions exist, suggesting a complicated evolutionary history for humanity. This can be seen with the global frequency patterns of the type B blood allele (shown in the map below).

Note that it is highest in Central Asia and lowest among the indigenous peoples of the Americas and Australia. However, there are relatively high frequency pockets in Africa as well. Overall in the world, B is the rarest ABO blood allele. Only 16% of humanity have it. Distribution of the B type blood allele in native populations of the world The A blood allele is somewhat more common around the world than B. About 21% of all people share the A allele. The highest frequencies of A are found in small, unrelated populations, especially the Blackfoot Indians of Montana (30-35%), the Australian Aborigines (many groups are 40-53%), and the Lapps, or Saami people, of Northern Scandinavia (50-90%). The A allele apparently was absent among Central and South American Indians. Distribution of the A type blood allele in native populations of the world The O blood type (usually resulting from the absence of both A and B alleles) is very common around the world. About 63% of humans share it. Type O is particularly high in frequency among the indigenous populations of Central and South America, where it approaches 100%.

It also is relatively high among Australian Aborigines and in Western Europe (especially in populations with Celtic ancestors). The lowest frequency of O is found in Eastern Europe and Central Asia, where B is common. Distribution of the O type blood in native populations of the world Other Blood Type Systems The majority of the people in the world have the Rh+ blood type. However, it is more common in some regions. Native Americans and Australian Aborigines were very likely 99-100% Rh+ before they began interbreeding with people from other parts of the world. This does not imply that Native Americans and Australian Aborigines are historically closely related to each other. Most Subsaharan African populations are around 97-99% Rh+. East Asians are 93-99+% Rh+. Europeans have the lowest frequency of this blood type for any continent. They are 83-85% Rh+. The lowest known frequency is found among the Basques of the Pyrenees Mountains between France and Spain. They are only 65% Rh+. The distribution patterns for the Diego blood system are even more striking.

Evidently, all Africans, Europeans, East Indians, Australian Aborigines, and Polynesians are Diego negative. The only populations with Diego positive people may be Native Americans (2-46%) and East Asians (3-12%). This nonrandom distribution pattern fits well with the hypothesis of an East Asian origin for Native Americans. Conclusion These patterns of ABO, Rh, and Diego blood type distributions are not similar to those for skin color or other so-called "racial" traits. The implication is that the specific causes responsible for the distribution of human blood types have been different than those for other traits that have been commonly employed to categorize people into "races." Since it would be possible to divide up humanity into radically different groupings using blood typing instead of other genetically inherited traits such as skin color, we have more conclusive evidence that the commonly used typological model for understanding human variation is scientifically unsound. The more we study the precise details of human variation, the more we understand how complex are the patterns. They cannot be easily summarized or understood. Yet, this hard-earned scientific knowledge is generally ignored in most countries because of more demanding social and political concerns. As a result, discrimination based on presumed "racial" groups still continues.

It is important to keep in mind that this "racial" classification often has more to do with cultural and historical distinctions than it does with biology. In a very real sense, "race" is a distinction that is created by culture not biology. Blood Type Chart: Facts & Information on Blood Group Types - Disabled World Blood Type Chart: Facts & Information on Blood Group Types Print Published: 2012-09-28 (Rev. 2016-05-30) - Contact: Ian Langtree at Disabled World Synopsis: Information regarding blood types including charts outlining donor compatibility and childs blood group from parents blood type. About Blood Type (Group) A blood type (also called a blood group) is defined as the classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells (RBCs). A series of related blood types constitutes a blood group system, such as the Rh or ABO system. The frequencies of the ABO and Rh blood types vary from population to population.

Main Document "While blood types are 100% genetically inherited, the environment potentially can determine which blood types in a population will be passed on more frequently to the next generation." When a person's blood is analyzed under a microscope distinct blood differences are visible. In the early 20th century, an Austrian scientist named Karl Landsteiner classified blood according to those differences. Landsteiner observed two distinct chemical molecules present on the surface of the red blood cells . He labeled one molecule "A" and the other molecule "B". Blood Type A - If the red blood cell has only "A" molecules on it. Blood Type B - If the red blood cell has only "B" molecules on it. Blood Type AB - If the red blood cell has a mixture of both "A" & "B" molecules. Blood Type O - If the red blood cell has neither "A" or "B" molecule. Blood Type Facts: There are eight different common blood types, which are determined by the presence or absence of certain antigens, which are substances that can trigger an immune response if they are foreign to the human body.

Since some antigens can trigger a patient's immune system to attack the transfused blood, safe blood transfusions depend on careful blood typing and cross-matching. There are 4 major blood groups determined by the presence or absence of two antigens (A and B) on the surface of red blood cells: Blood Group Has only B antigen on red cells (and A antibody in the plasma) AB Has both A and B antigens on red cells (but neither A nor B antibody in the plasma) O Has neither A nor B antigens on red cells (but both A and B antibody are in the plasma) In addition to the A and B antigens, there is a third antigen called the Rh factor, which can be either present (+) or absent ( - ). In general, Rh negative blood is given to Rh-negative patients, and Rh positive blood or Rh negative blood may be given to Rh positive patients. The universal red cell donor has Type O negative blood type. The universal plasma donor has Type AB positive blood type. Donating Blood by Compatible Type: Blood types are very important when a blood transfusion is necessary. In a blood transfusion, a patient must receive a blood type compatible with his or her own blood type.

If the blood types are not compatible, red blood cells will clump together, making clots that can block blood vessels and cause death. If two different blood types are mixed together, the blood cells may begin to clump together in the blood vessels, causing a potentially fatal situation. Therefore, it is important that blood types be matched before blood transfusions take place. In an emergency, type O blood can be given because it is most likely to be accepted by all blood types. However, there is still a risk involved. Blood Type AB- A- B- O- Finding Out Your Blood Type: It is easy and inexpensive to determine a person's ABO type from a few drops of blood. A serum containing anti-A antibodies is mixed with some of the blood. Another serum with anti-B antibodies is mixed with the remaining sample. Whether or not agglutination occurs in either sample indicates the ABO type. It is a simple process of elimination of the possibilities. For instance, if an individual's blood sample is agglutinated by the anti-A antibody, but not the anti-B antibody, it means that the A antigen is present but not the B antigen. Therefore, the blood type is A. Blood type is inherited, just like eye color.

This chart shows the possible blood type of a child according to their parents blood group: Parent 1 B AB Note: In most cases, blood typing is not conclusive when attempting to determine, include or exclude an individual as the parent of a child or children. While blood types are 100% genetically inherited, the environment potentially can determine which blood types in a population will be passed on more frequently to the next generation. It does this through natural selection. Specific ABO blood types are thought to be linked with increased or decreased susceptibility to particular diseases. What Does Blood Group RH Factor Mean RH factor in blood types stands for "Rhesus Factor". Blood tests were performed on Rhesus monkeys and the Rh+ and Rh- factors were isolated. An antigen found in the red blood cells of most people: those who have Rh factor are said to be Rh positive (Rh+), while those who do not are Rh negative (Rh-). What about the meaning of RHD- Rh blood group, D antigen .

The rhesus complex is not just one antigen, but several, when someone is told to be Rh+, it usually refers to the D antigen (one of the components of the Rh complex), because it's the most common, and the easiest to identify, however it's not the only one. What is the Rarest Blood Type According to the American Red Cross the rarest is AB(-), present in 1% of the Caucasians, in African Americans it is even rarer. B(-) and O(-) are also very rare, each accounting for less than 5% of the world's population. Some people with rare blood types bank their own blood in advance of surgical procedures to ensure that blood is available to them. Blood Type Diet: The Eat Right for Your Type diet encourages people to eat certain foods and avoid others based on their blood type A, B, AB, or O. The Diet is Based on: Type A ("for agrarian") - Flourishes on vegetarian diets, "the inheritance of their more settled and less warlike farmer ancestors," says D'Adamo. The type A diet contains soy proteins, grains, and organic vegetables and encourages gentle exercise.

Type B - The nomadic blood type B has a tolerant digestive system and can enjoy low-fat dairy, meat, and produce but, among other things, should avoid wheat, corn, and lentils, D'Adamo says. If you're type B, it's recommended you exercise moderately. Type O ("for old," as in humanity's oldest blood line) - Your digestive tract retains the memory of ancient times, says D'Adamo, so your metabolism will benefit from lean meats, poultry, and fish. You're advised to restrict grains, breads, and legumes, and to enjoy vigorous exercise. Type AB - Has a sensitive digestive tract and should avoid chicken, beef, and pork but enjoy seafood, tofu, dairy, and most produce. The fitness regimen for ABs is calming exercises. NOTE: Critics cite a lack of published evidence backing D'Adamo's blood type-based diet plan. Blood Type and Your Personality: Legend has it that blood type tells about personality. In Japan, it's widely believed that blood groups predict personality traits - from temperament to compatibility, to what kind of lover you are to what type of foods you should be eating.

For instance: Type A is calm and trustworthy; Type B is creative and excitable; Type AB is thoughtful and emotional; Type O is a confident leader. Printable Blood Group/Type Charts: Printable chart showing compatible blood types for receiving blood transfusions Printable chart showing possible blood type of a child according to their parents blood group Blood & Heart Awareness The red ribbon raises awareness of blood and heart diseases including Cardiovascular Disease, Congenital Heart Defects, Hemophilia, Hypertension, Lymphoma, and other conditions relating to the heart and human blood. Other awareness dates Facts: Blood Type A total of 35 human blood group systems are now recognized by the International Society of Blood Transfusion (ISBT). With regard to transfusions of packed red blood cells, individuals with type O Rh D negative blood are often called universal donors, and those with type AB Rh D positive blood are called universal recipients. Many pregnant women carry a fetus with a blood type which is different from their own, which is not a problem A popular belief in Japan is that a person's ABO blood type is predictive of their personality, character, and compatibility with others.

Rarest Blood Type: A blood type is considered rare if fewer than 1 in 1,000 people have them. One of the rarest blood types in the world is Rh-null, which lack any antigens in the Rh system. There are only 9 active donors in the community of rare blood donors that have Rh-null blood. Rh-null is considered a universal blood for anyone with a rare blood type within the Rh system. However, anyone who has Rh-null blood can only receive Rh-null blood in a transfusion. Statistics: Blood Group Your body carries around four to six liters (7 to 10.5 pints) of blood. About 5 million Americans need blood transfusions every year. Receiving blood from the wrong ABO group can be life threatening. Almost half (48%) of the UK population has blood group O, making this the most common blood group. Human Blood: ABO Blood Types (1868-1943) The most well-known and medically important blood types are in the ABO group.

They were discovered in 1900 and 1901 at the University of Vienna by Karl Landsteiner in the process of trying to learn why blood transfusions sometimes cause death and at other times save a patient. In 1930, he belatedly received the Nobel Prize for his discovery of blood types. All humans and many other primates can be typed for the ABO blood group. There are four principal types: A, B, AB, and O. There are two antigens and two antibodies that are mostly responsible for the ABO types. The specific combination of these four components determines an individual's type in most cases. The table below shows the possible permutations of antigens and antibodies with the corresponding ABO type ("yes" indicates the presence of a component and "no" indicates its absence in the blood of an individual). It is easy and inexpensive to determine an individual's ABO type from a few drops of blood. A serum containing anti-A antibodies is mixed with some of the blood. Another serum with anti-B antibodies is mixed with the remaining sample. Whether or not agglutination occurs in either sample indicates the ABO type. It is a simple process of elimination of the possibilities.

For instance, if an individual's blood sample is agglutinated by the anti-A antibody, but not the anti-B antibody, it means that the A antigen is present but not the B antigen. Therefore, the blood type is A. Genetic Inheritance Patterns Research carried out in Heidelberg, Germany by Ludwik Hirszfeld and Emil von Dungern in 1910 and 1911 showed that the ABO blood types are inherited. We now know that they are determined by genes on chromosome 9, and they do not change as a result of environmental influences during life. An individual's ABO type results from the inheritance of 1 of 3 alleles (A, B, or O) from each parent. The possible outcomes are shown below: The possible ABO alleles for one parent are in the top row and the alleles of the other are in the left column. Offspring genotypes OO (O) Both A and B alleles are dominant over O. As a result, individuals who have an AO genotype will have an A phenotype . People who are type O have OO genotypes. In other words, they inherited a recessive O allele from both parents. The A and B alleles are codominant.

Therefore, if an A is inherited from one parent and a B from the other, the phenotype will be AB. Agglutination tests will show that these individuals have the characteristics of both type A and type B blood. CAUTION: the inheritance of ABO blood types does not always follow such straightforward rules of inheritance. If you wish to explore the reason why this is true, select the Bombay Phenotype button below. Bombay Phenotype ABO Blood type antigens are not only found on the surface of red cells. They are also normally secreted by some people in their body fluids, including saliva, tears, and urine. Whether someone is able to secrete them is genetically controlled. Police agencies now routinely use this so-called secretor system data to identify potential victims and criminals when blood samples are not available. Despite the fact that the blood types of children are solely determined by inheritance from their parents, paternity in the U.S. and many other nations can no longer be legally established based on conventional blood typing. To do that, it is necessary to compare HLA types and/or DNA sequences. The use of DNA is more accurate in determining paternity, but it is also more expensive than HLA typing.

Antibodies to alien antigens in the ABO group are usually present in our plasma prior to the first contact with blood of a different ABO type. This may be partly explained by the fact that these antigens are also produced by certain bacteria and possibly some plants. When we come in contact with them, our bodies may develop long-term active immunity to their antigens and subsequently to the same antigens on the surface of red blood cells. This usually occurs in babies within the first six months following their birth. Environmental Factors While blood types are 100% genetically inherited, the environment potentially can determine which blood types in a population will be passed on more frequently to the next generation. It does this through natural selection . Specific ABO blood types are thought to be linked with increased or decreased susceptibility to particular diseases. For instance, individuals with type A blood are at a somewhat higher risk of contracting smallpox and developing cancer of the esophagus, pancreas, and stomach. People who are type O are at a higher risk for contracting cholera and plague as well as developing duodenal and peptic ulcers. Research suggests that they are also more tasty to mosquitoes. That could be a significant factor in contracting malaria.

NOTE: A small number of people have two different ABO blood types. They are not simply AB codominant. Apparently, most of these blood chimera individuals shared a blood supply with their non-identical twin before birth. In some cases, people are unaware that they had a twin because he or she died early in gestation and was spontaneously aborted. As many as 8% of non-identical twins may have chimeric blood. Some people are microchimeric--they have a small amount of blood of a different type in their system that has persisted from a blood transfusion or passed across the placental barrier from their mother before birth. Likewise, fetal blood can pass into a mother's system. This fact has led some researchers to suggest that the significantly higher frequency of autoimmune disorders in women is a result of the presence of foreign white blood cells that had come from their unborn children during pregnancy. NEWS: An international team of researchers led by Henrick Clausen of the University of Copenhagen, Denmark have discovered a bacterial enzyme that can convert red blood cells of types A, B, and AB into O by stripping away their identifying surface antigens. This has the potential for dramatically improving the safety of blood transfusions.

Clinical trials of this technique are now underway. ("Bacterial Glycosidases for the Production of Universal Red Blood Cells", published online in Nature Biotechnology, April 1, 2007.) NEWS: A research team led by Peer Bork of the European Molecular Biology Laboratory in Heidleberg, Germany discovered that people can be classified into one of 3 distinct types based on the kinds of bacteria in their guts. They refer to them as enterotypes. This type system is independent of blood types and may have equally important implications for peoples' health. How enterotypes are established is not known, but the authors suggest that babies may be randomly colonized by different species of bacteria and that they alter the gut so that only certain species of bacteria can live there. ("Enterotypes of the Human Gut Microbiome", published online in Nature, April 20, 2011.) Understanding Genetics Is it true that in earlier times humans were all O blood type (in ABO blood group) and that A, B and AB blood type occurred later by mutation of the O blood type gene? -A curious adult from Thailand January 13, 2010 No this probably isn't the way it happened. Most likely A came first.

And then mutations in the original A gene caused B and O to appear. One way scientists figured this out was by using something called coalescence analysis . Basically, this is where you compare DNAs and figure out when they used to be the same. From this kind of analysis scientists concluded that A came first. Then, about 3.5 million years ago, the A gene mutated in someone and blood type B was born. The same thing happened about a million years ago for O blood type. So O is actually the most recent blood type. At first this might seem weird since O is the most common blood type, but these kinds of things happen all the time. Different traits can become more common over time for lots of different reasons . For example, if a trait gives some sort of advantage, it can quickly become the norm. How quickly this happens depends on how big an advantage the trait gives. So what's the use of having O blood? One theory is that it makes people suffer less severe symptoms from malaria. As I said earlier, humans probably started with mostly A type blood. In areas with lots of malaria, these A folks lived shorter lives and had fewer babies than the O ones. Over time, the O folks slowly came to dominate.

This is one way that O might have become the most common human blood type. And there are many others possible ways , some of which don't even require an advantage. What I'll do for the rest of the answer is talk a bit about how genes get changes in them to create new traits. In other words, for our discussion here, how did O and B spring from A? I'll also talk a bit about why having an O blood type can make you suffer less from malaria. Blood type B and O came from A If humans started out as A blood type, where did O and B come from? They came from small changes in the A gene. To understand how this happened, we need to step back a bit and discuss genes and DNA. Because A, B, and O are all the result of one of our genes. Each of our thousands of genes has the instructions for one small part of us. The gene we're interested in is called ABO. This gene comes in three different versions -- A, B, and O. The four common blood types all come from different combinations of these versions (or alleles as scientists like to call them). The instructions in genes are written in DNA.

The alphabet of this language has just four letters -- A, G, C, and T. The ABO gene has around 20,000 of these letters all arranged in a certain order. The differences between the three different ABO alleles are actually very small. There is only a single difference between O and A and just four between A and B. These kinds of differences originally came from things like environmental damage or mistakes our own cells made copying DNA. DNA changes like these are surprisingly common. Given that many of these mutations are not good for us, we're lucky that our cells are nearly perfect at fixing them. But our cells don't catch all mutations--some are missed. Sometimes one of these missed mistakes can cause problems like cancer or cystic fibrosis. But sometimes they can be helpful too. Like when they change A to O and this happens to give some protection against malaria. Malarial Protection So how does a single letter change protect someone from malaria? It does this by affecting the protein that gets made. In order for a gene to perform its function, its instructions must be read and a protein made. It is the protein that goes off and does the work.

To get from DNA to protein, a cell needs to read a gene's instructions. Remember when I said that the genetic language has only four letters? Well, it also only has 64 three-letter words. This is called the genetic code. Each combination of 3 letters makes up an amino acid and proteins are made up of these amino acids. So, a gene is really just a long string of three letter words that tells a cell to connect amino acids in a certain order. Now imagine what would happen if you were to change (mutate) one of the letters that codes for an amino acid. Let's take as an example the amino acid leucine. Genes are written in a four letter alphabet with these three letter words. There are six different words that mean leucine. We'll just focus on one -- UUA. If one of the letters were changed (or mutated), then you might get UUU. Now instead of leucine, you have phenylalanine. It is like putting the wrong word in the middle of a sentence. It's as if you wanted to write CAR but instead you wrote CAT. This is exactly the difference between allele A and B except that there are four differences like this instead of one.

These differences that make up the B allele result in a different blood protein. This protein still works like it should. What about the O allele? Well, as we said before, the O allele differs at only one location from the A allele. But what a big difference it is! Instead of changing a letter, the O allele is actually missing one. What happens is that every "word" after this change is wrong. Which means that a bunch of gibberish gets made. To see what I mean, imagine the sentence: The old man had one new hat. Now imagine what happens when you get rid of the first e. Because of the way a cell reads a gene, it only "sees" three letter words. Which means the new sentence is: Tho ldm anh ado nen ewh at. So you end up with a protein getting made that can't do much of anything. For the O allele, very shortly after the missing letter, one of the new three letter words that gets made is a stop codon. Stop codons are sort of like a period in a sentence -- they tell a cell when to stop reading a gene.

Ultimately this means that for the O allele, we end up with half a protein that has a lot of the wrong amino acids. Our cells can't use these kinds of proteins so it is like the protein isn't even there. And apparently for a malaria infection to really take hold, it needs an A or B protein. Malaria is caused by a parasite that is transmitted from mosquitoes to men. Once this parasite enters your body it lives in your red blood cells. The parasite doesn't seem to have any trouble getting into an O blood cell. But it does have trouble quickly spreading from cell to cell. Malaria symptoms come from these parasites destroying lots of red blood cells. If they can't infect as many, the symptoms will be less severe. This is one possible reason why O blood type came to dominate. So we all started out with A blood type. Some lucky person developed a mutation that caused the A to convert to O. Now that person (and his or her offspring) was more resistant to malaria and so lived longer and had more babies. After awhile, O came to dominate human blood types. That's one theory anyway. Video on the science of blood type set to music.

Question: The most common human bloodgroup is?
Answer: O