IB 169: Case 2 O Blood Type

Why is this Native American O blood type/phenotype and OO genotype?

more native populations with O phenotype in mexico / west coast

Heterozygous dominant, recessive, co-dominant, & incomplete dominant genes in monogenic Mendelian genetics

The allele that masks the other allele is called be dominant. The allele that is masked is called recessive. When both alleles (e.g., blood type AB) are fully expressed they are co-dominant. Two different alleles are expressed as an intermediate between the two, is an example of incomplete-dominance

OO genotype is universal donor

A person with OO genotype can make both anti-A or anti-B antibodies and therefore can NOT receive blood from the AA, BB, AB, AO, or BO genotypes because they will reject the blood A person with OO genotype can ONLY receive blood from a person with the OO genotype. People with OO genotype (O phenotype) are universal donors, because antibodies are not formed against O blood type by people with A, B, AB, or O blood types

Maternal exposure to fetal RBCs during pregnancy

A small number of fetal RBCs cross the placenta and enter the mom's blood during the 2nd and 3rd trimesters Maternal-fetal ABO blood group incompatibility - If mom is blood group O conceives a fetus who is blood group A or blood group B, a small amount of fetal blood cells can leak into the maternal blood circulation - The group O mom may develop anti-A and/or anti-B IgG antibodies to these fetal blood type antigens - These maternal anti-A or anti-B IgG antibodies can then pass through the placenta into the fetal circulation and cause destruction of fetal RBCs which can result in reduced RBCs and elevated bilirubin - ABO maternal-fetal blood group incompatibility typically results in significantly less severe effects on the fetus/infant compared to Rh incompatibility

Chumash Indian patient outcome

Because no O type blood was available, this male was immediately given fluids to maintain his blood pressure. Soon after his arrival into the ER, two of his sisters arrived and both had their blood immediately typed and both were O type/phenotype. Blood was donated at that time from his sisters and he was given a transfusion of fresh O type/phenotype blood. He recovered from his injuries and was discharged to go home three days later.

Influence of blood type/phenotype expression by interaction of two dominant alleles (A & B) with one recessive allele (O)

Both A allele and B allele mask the recessive O allele so the frequency of O blood type/phenotype in the contemporary California human population is much lower that the O allele frequency in the population O blood type is the universal donor and can be received by any ABO blood type These features contribute to the relatively low supply of O blood type/phenotype in California today. The supply of donor blood is further limited for people with O blood type/phenotype because they are universal donors and can onlyreceive O type blood

Bottlenecks, founder effects, and subsequent population growth

Bottleneck generated a small population compared to original source population size. This small population tended to be influenced by genetic drift but could have also be influenced by natural selection, however, there was not likely a significant selective force for the O allele over the A or B alleles for the populations as they migrated into the Americas.

Mendelian Monogenic Inheritance Homozygous vs heterozygous

Homozygous: the pair of alleles at a locus are identical. Heterozygous: the pair of alleles at a locus are different A population of organisms within a species may include multiple alleles at the locus among various individuals. Allelic variation at a locus is measurable as the number of different alleles present, or the proportion of heterozygotes at that locus in the population.

ABO alleles & disease susceptibility

O allele is more susceptible to the bubonic plague A allele is more susceptible to small pox May account for the increased frequency of the B allele in China, India and parts of Russia, which suffered epidemics of both of these diseases O allele carriers are more susceptible to Helicobacter pylori infections It has been suggested that the O allele protects against severe malaria (Since malaria was not present in the Americas when Homo sapiens migrated in, there would not have been a selective advantage for this allele)

ABO system

The ABO systemis the most important blood-group system in determining appropriate donors and recipients for human-blood transfusions. ABO is transmitted through monogenic inheritance. Humans may have the same blood type phenotype (characteristic) but different genotypes (gene sequences) Three blood type alleles: A, B, & O Each human has two of these alleles A or B are each dominant over O which is recessive, but neither A or B are dominant over each other Six possible genotypes: AA, AO, BB, BO, AB, OO Four blood types/phenotypes: A, B, AB, & O AA genotype: phenotype A BB genotype: phenotype B AB genotype: phenotype AB (universal recipient) AO genotype: phenotype A BO genotype: phenotype B OO genotype: phenotype O (universal donor) Both parents need to be homozygous for OO for all offspring to be genotype OO and O blood type/phenotype. Depending on the person's blood type, they may develop anti-A antibodies, anti-B antibodies, or no antibodies Anti-O antibodies are NOT formed by humans Persons with the genotype AA, AO, or OO will form anti-B antibodies if they are exposed to blood from a person with a BB, AB, or BO genotype, causing them to rejection the blood. Persons with the genotype BB, BO, or OO will form anti-A antibodies if they are exposed to blood from a person with a AA, AB, or AO genotype, causing them to rejection the blood. Persons with genotype OO will form both anti-A and anti-B antibodies when exposed to A and B alleles Persons with genotype AB form no antibodies

Blood types in the USAData from Stanford Blood Center

Type A = 42% Type B = 10% Type AB = 4% (universal recipient) Type O = 44% (universal donor)

Acute hemolytic reaction from rejection of blood transfusion because of ABO blood type mismatch

Type O blood recipient will reject any blood type (A, B, & AB) other than Type O blood Type B blood recipient will reject blood types A & AB Type A blood recipient will reject blood types B & AB Type AB blood recipient will accept all blood types (= universal recipient)

Human blood transfusions

Use of human blood transfusions is relatively recent in human history. In relationship to blood transfusions, the disadvantage that people with Type O blood phenotypes have and the advantage that Type AB blood phenotypes have are recent in human history and are not traits that have been influenced by selection based on ability to receive life saving blood transfusions

What genotypes generate O type blood?

Three blood type alleles: A, B, & O Each human has two of these alleles A or B are each dominant over O which is recessive, but neither A or B are dominant over each other When both A and B alleles (blood type AB) occur together they are co-dominant

Human blood types

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 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.

Incomplete dominance

A heterozygous condition in which both alleles at a gene locus are partially expressed, often producing an intermediate phenotype Incomplete dominance is sometimes called partial dominance or intermediate dominance i.e. if heterozygotes are Pink instead of red i.e. AA AB AB BB blood types

AB genotype is universal recipient

A person with AB genotype is not capable of making anti-A or anti-B antibodies and can receive blood from any of the genotypes (i.e. AA, BB, AB, AO, BO, OO). People with AB genotype (AB phenotype) are universal recipients

Why was O type/phenotype blood in relatively low supply in contemporary California population?

All three blood type alleles (A, B, & O) are present in contemporary California human populations which are made up predominantly of people whose ancestors originated from Latin America, Europe, Asia, Africa, and Oceania in addition to a small percentage of Native California Indians A & B are dominant O is recessive Blood type O can be given to any ABO blood type recipient, hence it can be used up quickly causing the available supply of type O blood to be less at this community hospital

ANSWER: What was the evolutionary pathway responsible for the high amount of O blood type phenotype in Native Americans?

Answer: Outcome of demographic history with migration of small population producing a bottleneck which generated in a founder effect which resulted in the high blood O allele frequency in the population which was likely fixed through drift.

Blood phenotype B

Blood group B is in highest frequency in northern India and Central Asia Believed to have been entirely absent from Native American and Australian Aboriginal populations prior to the arrival of Europeans. Today, frequency of type B blood allele in Native Americans is 4%, even though Type B blood allele is significantly more common in the Asian population from where the Native Americans migrated.

O allele and cholera susceptibility

O allele is more susceptible to severe forms of cholera infections Severe life-threatening cholera associated with blood group O in Peru: implications for the Latin American epidemic. Cholera was not present in the Americas in pre-Columbian times. The higher rates of the B allele in northern India give people more protection against cholera

What was the evolutionary pathway responsible for the high amount of O blood type phenotype in Native Americans?

Human migration to the Americas At least 20,000 years ago the migration into the Americas occurred. One or more migrations by relatively small groups of Siberian humans over the landmass called Beringia which connected present day Siberia and Alaska between 20,000-8,000 years ago because of the fallen ocean level during the last glacial period As the North American glaciers began to melt and recede about 20,000 years ago, the way for southward migration was opened and Homo sapiens reached southern South America as early as 14,000 years ago. Population bottlenecks from migration of small groups from the original population have resulted in founder effects which have caused a high level of genetic homogeneity in Native Americans in North America, Mexico, Central America, and South America. Some scientists suggest that the original founder population in the Americas may have been 70 or fewer individuals. Amerindians are found to mostly have blood phenotype O (genotype OO); this high frequency of blood type O is thought to be due to a genetic bottleneck that generated a founder effect. An example of the low genetic diversity in Native Americans is the fact that nearly all have blood phenotype O/genotype OO (especially in western USA, Mexico, Central American and South American Indians), with a very low frequency of blood type A and blood type

Genetic drift

In large populations, in the absence of selection, allele frequencies tend to change very slowly over generations. In small populations, in the absences election, the stochastic nature of reproductive processes means that alleles may be lost (0% frequency in the population) or fixed (100% frequency in the population) within a few generations.

Blood phenotype B has some protection against cholera

It is believed that the high frequency of blood phenotype B in northern India along the Ganges River basin is because it was positively selected for since of it offers protection against cholera diarrhea.

Blood types

The only blood available was A, AB, and B blood types (phenotypes). This Native American Chumash male is O blood type (O phenotype) and can only receive O blood type. Chumash Indian ancestral distribution is along the coast in southern California

When there is an abnormally high breakdown of red blood cells, the blood bilirubin level rises

This 30 year old Chumash Indian male was injured in a car accident and arrives by ambulance to the emergency room of a small hospital in California. Due to multiple lacerations, he has lost a fair amount of blood and his blood pressure is 40/90 which is dangerously low. He needs a blood transfusion emergently He is O type (O phenotype) blood. Unfortunately, there is no O type blood available in this small community hospital.

Bilirubin

Yellow breakdown product of hemoglobin When there is an abnormally high breakdown of red blood cells, the blood bilirubin level rises