MediaLab Blood Bank
A febrile nonhemolytic transfusion reaction is characterized by which of the following? The correct answer is highlighted below An increase in temperature of >1oC above 37oC during transfusion Appearance of hives Fever above 37oC which develops 24 hours later A decrease in temperature of < 2oC below 37oC following transfusion
One of the symptoms of febrile nonhemolytic transfusion reactions (FNHTR) is a >1oC rise in temperature above 37oC, associated with transfusion. Other symptoms include chills, rigors, headache and vomiting. In allergic transfusion reactions, one of the symptoms is hives and itching within 15-20 minutes of transfusion. In delayed hemolytic transfusion reaction, the symptoms can occur >24 hours to 28 days. Since it is a febrile reaction, there would not be a decrease in temperature.
What additional information is required on a label or tie tag of an autologous unit? The correct answer is highlighted below Name of the ordering physician Identification of the recipient Location of the collection facility The statement "For Emergency Use Only"
In addition to the routine labeling of the autologous blood bag, the name of the donor, the recipient, the blood group, and the name of the hospital must be included along with the phrase "for autologous use only."
In providing crossmatch-compatible blood units, all of the following antibodies are most often clinically insignificant EXCEPT: The correct answer is highlighted below Anti-Jkb Anti-P1 Anti-M Anti-Lea
Anti-Jkb is considered a clinically significant antibody. Typically, anti-Jkb presents as an IgG antibody and optimally reacts at 37°C in the IAT phase. Anti-P1 and anti-M (IgM agglutinins) optimally react at 4°C and are not associated with HDFN. Anti-Lea, an IgM antibody, is detected in the immediate spin phase (room temperature) and rarely known to cause HTR or HDN. Crossmatch-compatible units that test negative at 37°C and negative through the antiglobulin phase are considered acceptable for transfusion.
All of the following are reasons for conducting compatibility testing EXCEPT: The correct answer is highlighted below Prevent recipient alloimmunization Verify ABO and Rh Select proper blood products Detect antibodies against donor cells
Compatibility testing is performed by the blood bank laboratory to detect serologic incompatibilities that might result in decreased survival of donor red cells in the transfused patient, but cannot prevent alloimmunization of the recipient to antigens on transfused cells since patients and donor units are not phenotyped for every antigen prior to transfusion. The term compatibility testing, also known as pretransfusion testing, describes a set of procedures required before blood is issued as being compatible. Compatibility testing includes verification of ABO and Rh, selecting the proper blood products for transfusion, and detecting antibodies against donor cells to help avoid potential transfusion reactions.
An Rh negative mother has just given birth to an Rh positive baby. Her physician suspects that she has experienced a fetal-maternal hemmorhage since her rosette test was positive. Upon performing the Kleihauer-Betke stain procedure, the percentage of fetal cells is found to be 0.85%. The mother's total blood volume is 4,565 mL. What dose of Rh Immune Globulin (RhIG or RhoGam) should be administered to the mother? The correct answer is highlighted below 1 vial 2 vials 3 vials 4 vials
Rh immune globulin, also known as RhIG or RhoGam, is used to help prevent an Rh negative mother from becoming sensitized to the D antigen from an Rh positive baby. To do this, vials of Rh Ig must be administered correctly. One full dose vial (300µg or equivalent) per 30 ml of D positive whole blood (15 ml D positive packed RBCs). To calculate how many vials are needed, the following formula can be employed: KB% x blood volume = volume of baby blood In this case: 0.85% (0.0085) x 4,565mL= 38.8 mL baby blood in maternal circulation 38.8mL / 30 mL per Rh Ig vial = 1.29 vials 1.29 vials can be rounded to 1 vial. In addition, an extra vial is always added. Therefore, 2 vials is the correct answer.
Which is in the correct order from the lowest concentration of H antigen to the highest concentration of H antigen? The correct answer is highlighted below Bombay, A1B, A1, A2B, B, A2, O A1, O, B, A2, Bombay, A1B, A2B Bombay, O, A1B, A2, A1, B, A2B A1B, A2B, A2, O, B, A1, Bombay
The H antigen is an essential precursor to the ABO blood group antigens. Individuals with the rare Bombay phenotype (hh) do not express antigen H on their red blood cells; therefore, this type would contain the least amount of H antigen. Those which are type A1B would then have the second to least amount of H antigen since the precursor H antigens have been formed into A1 and B antigens instead. The remaining order of the H concentration from lowest to highest in the blood types given is: A1, A2B, B, A2, and O. O patients produce the most H antigen since they do not convert the H antigen into A or B antigens on their cell surface.
When a unit of packed RBC's is split using the open system, each portion of the unit must be issued: The correct answer is highlighted below Within 24 hours Within 48 hours Within 30 days By the original expiration date
The correct answer is within 24 hours. If a unit is entered without use of a sterile connection device (open system) it must be used within 24 hours of entry. Closed systems retain the same expiration date as the original whole blood unit.
Which of the following signs and symptoms may be associated with immediate transfusion reaction, but is NOT usually associated with delayed hemolytic transfusion reaction? The correct answer is highlighted below Fever and chills Unexplained bleeding from surgical site Unexplained drop in hemoglobin Transient jaundice
Unexplained bleeding is associated with immediate hemolytic transfusion reactions, but is not usually associated with delayed hemolytic transfusion reactions. The bleeding results from disseminated intravascular coagulation (DIC) which can be activated by the antigen-antibody-complement complexes that form in an immediate hemolytic reaction. Fever, chills, transient jaundice and a drop in hemoglobin would be more likely present in cases of delayed hemolytic transfusion reactions.
A delayed hemolytic reaction occurring a week later is MOST likely caused by: The correct answer is highlighted below Volume overload Kidd system antibodies Iron overload ABO incompatibility
Delayed hemolytic transfusion reactions occur more than 24 hours after a transfusion and result in the hemolysis of red blood cells. Of the causes that are listed, the most likely cause of a delayed hemolytic reaction is Kidd system antibodies. Both Jka and Jkb are often responsible for delayed hemolytic transfusion reactions. Volume overload may cause an acute, nonhemolytic (nonimmunological) reaction. Iron overload may cause a delayed, nonhemolytic (nonimmunological) reaction. ABO incompatibility would cause an acute hemolytic (immunological) reaction.
Which of the following set of conditions would NOT allow HDFN to occur as a result of Rh incompatibility? The correct answer is highlighted below Mother Rh-negative, father Rh-positive Mother Rh-negative, baby Rh-positive Mother Rh-negative, father Rh-negative Mother Rh-negative, father Rh-unknown
If both parents are Rh-negative, the baby would also be Rh-negative, and HDFN due to Rh incompatibility would not occur. For Rh HDFN to occur, the baby must be Rh-positive and the mother Rh-negative. If the father is Rh-positive, then there is a likely probability the baby will be Rh-positive, and thus the potential for Rh HDFN. If the Rh type of the father is unknown, it is common to assume that the father is Rh-positive due to statistical probability, and thus the potential for Rh HDFN exists.
Which antibody is associated with Mycoplasma pneumoniae infection and cold hemagglutinin disease? The correct answer is highlighted below Anti-P Anti-I Anti-M Anti-i
M. pneumoniae carries an antigen that resembles I antigen. Thus, when the body develops an immune response against this antigen, the antibodies may cross react with I antigen on red blood cells. Anti-I is also associated with cold hemagglutinin disease. Anti-P may be associated with paroxysmal cold hemoglobinuria. Anti-M can occur naturally and often reacts at room temperature but is not associated with a specific disease. Anti-i is associated with infectious mononucleosis, lymphoproliferative disease, and sometimes with cold hemagglutinin disease.
Why would a unit of group O blood never be administered to a Bombay patient? The correct answer is highlighted below Anti-A in donor Anti-B in donor Anti-H in donor Anti-H in recipient
The classic Bombay phenotype (Oh) is characterized by the absence of A, B and H antigens, and the presence of anti-H, which will react from 4o to 37o C. Because all ABO blood types possess the H antigen (varying amounts) on the surface of their red cells and the Bombay patient possess anti-H in their plasma, the only suitable blood for a Bombay patient would be blood from other Bombay phenotypes.
Which one of these physical exam results would cause a donor to be deferred? The correct answer is highlighted below A hemoglobin of 13.0 g/dL. A pulse of 75 A diastolic blood pressure of 110 mm Hg A temperature of 99.3 ºF
The correct answer is a diastolic blood pressure of 110 mm Hg. Donors must have a diastolic blood pressure must be less than 100 mm Hg. Donors must have a hemoglobin greater than or equal to 12.5 g/dL. Donors must have a pulse between 50-100 beats per minute. Donors must have a temperature at or below 37.5°C (99.5°F).
What is the rare phenotype found exclusively in male patients that is caused by X-linked inheritance from a carrier mother, often demonstrating a chronic but well-compensated anemia as well as muscle and nerve disorders? The correct answer is highlighted below Fy (a- b-) McLeod Jk (a- b-) U-
The correct answer is the McLeod phenotype, which also is indicated by a lack of the Kx and Km antigens, depressed expression of other Kell Blood Group antigens, and may be associated with X-linked chronic granulomatous disease (but this association is not always present). The Fy (a- b-) phenotype is found primarily in the African American population and is associated with resistance to malaria caused by P. vivax. The Jk (a- b-) phenotype is a very rare phenotype, but when present, is most often found in the Polynesian population. The U- phenotype is very rare and only exists in individuals who are both S- and s-.
When AHG or Coombs serum is used to demonstrate that red blood cells are antibody coated in vivo, the procedure is termed: The correct answer is highlighted below Indirect technique Direct technique Hemagglutination technique Hemolysis technique
The direct antiglobulin test (also known as "DAT") is performed to detect in vivo sensitization of RBCs with IgG or complement. In vivo coating of RBCs with IgG antibody or complement are associated with the following clinical conditions: autoimmune and drug-induced hemolytic anemia (AIHA), hemolytic disease of the fetus and newborn (HDFN), and hemolytic transfusion reaction (HTR). The indirect technique is performed to detect in vitro sensitization of RBCs for antibody screening and compatibility testing purposes. Both hemagglutination and hemolysis techniques are in vitro testing methods used for the detection of antigens or antibodies.
What is the shelf-life of whole blood collected in CPDA-1? The correct answer is highlighted below 21 days 28 days 35 days 48 days
Whole blood collected with CPDA-1, or citrate-phosphate-dextrose-adenine, has a storage (shelf) life of 35 days from the date of collection. Whole blood collected with CPD (citrate-phosphate-dextrose), CP2D (citrate-phosphate-dextrose-dextrose), or ACD (acid-citrate-dextrose) has a storage (shelf) life of 21 days from the date of collection.
Acute transfusion reactions are divided into categories based on all of the following symptoms EXCEPT: The correct answer is highlighted below Fever Liver failure Allergic reaction Pulmonary involvement
Acute transfusion reactions breakdown into three groups based on the presenting key clinical symptom: fever, allergic, or pulmonary. Liver failure is not indicated as a symptom in acute transfusion reactions. Fever is indicated in transfusion-associated sepsis (TAS), febrile nonhemolytic transfusion reaction (FNHTR), and acute hemolytic transfusion reaction (AHTR). Allergic (or allergy-mediated) transfusion reactions may be mild or severe. Pulmonary involvement is indicated in transfusion-associated circulatory overload (TACO) and transfusion-related acute lung injury (TRALI).
What is the maximum interval during which a recipient sample may be used for compatibility testing if the patient has recently been transfused or was pregnant within the past 3 months? The correct answer is highlighted below 24 hours 3 days One week Two weeks
If the patient has been recently transfused or pregnant within the past 3 months, then the maximum interval during which a recipient sample may be used for crossmatching is 3 days within the scheduled transfusion. Additionally, the maximum testing interval for compatibility testing is 3 days in cases when relevant medical and/or transfusion history is unknown. Donor and recipient samples are stored for a minimum of 7 days (or one week) following transfusion. Both 24 hours and two week time intervals are not included in compatibility testing protocols.
The term used to describe patients with absence of Rh antigens is: The correct answer is highlighted below Rhmod Rhnull Partial D Del
In rare cases individuals do not express any Rh antigens on their red blood cells. The term used to describe these individuals is Rhnull. Individuals that are Rhnull have mild compensated anemia, reticulocytosis, stomatocytosis, low hemoglobin and hematocrit, an increase in hemoglobin F, decreased serum haptoglobin, and in some cases increased bilirubin. If a transfusion is needed these patients would require blood from another Rhnull individual. Another set of individuals who are rare are those that have greatly reduced expression of Rh antigens due to suppression of RH gene. Rhmod individuals have symptoms similar to those listed above but general the symptoms are less severe and not as significant clinically. Partial D is a mechanism in which expression of D is weakened due to one or more D epitopes missing. These individuals are at risk for making an anti-D specific for the epitope that they are lacking. Expression of the other Rh antigens is normal in partial D. Del is a phenotype with very low D expression. Expression is so low in these patients that most anti-D will not detect the D antigen. Adsorption and elution methods can be used to detect the presence of D. Expression of the other Rh antigens is normal in Del.
Which Rh antibody might be produced if a unit of blood with Rh genotype DCe/dce is given to a patient with Rh genotype DCe/DCe? The correct answer is highlighted below Anti-C Anti-c Anti-D Anti-Cw
In this case, the c antigen is not present on the cells of the recipient. If this recipient is transfused with c-positive RBC units (i.e. DCe/dce), then there is a possibility that the recipient may form an antibody against the c antigen (anti-c) located on the donor RBCs. Exposure to the donor's RBC units (DCe/DCe) will not stimulate an immune response to D, C, or e antigens due to the expression of these antigens on the recipient's own RBCs.
Of the following blood group antibodies, which has been most frequently associated with severe cases of hemolytic disease of the fetus and newborn (HDFN)? The correct answer is highlighted below Anti-A,B Anti-Lea Anti-K Anti-M
Of those listed, anti-K is most frequently associated with severe forms of HDFN. Anti-K is considered the most clinically significant antibody outside of the Rh system. Kell antigens are found on both immature and mature red blood cells leading to destruction of precursor and circulating red blood cells. Anti-A,B is frequently implicated in HDFN, but the disease is generally mild, often subclinical. Anti-Lea is not implicated in HDFN for two reasons; the antibody is generally IgM and the Lewis system antigens are poorly developed at birth. Anti-M is not usually implicated in HDFN due to the fact that more anti-M is IgM.
The serum from a patient of African-American descent is reactive with all screening and panel cells. Which antibody directed to a high incidence antigen is most likely to be present? The correct answer is highlighted below Anti-Lub Anti-Jk3 Anti-U Anti-Ku
The U antigen is located on glycophorin B, a glycoprotein that carries the S, s, and U antigens in the MNS blood group system. Individuals who are U-negative are also S-s- and are of black descent. This phenotype is never found in the white population. The U antigen is present in more than 99% of the population. Anti-Lub is rarely seen because of the high prevalence of the antigen. The presence of anti-Lub is not associated with a specific ethnicity. Individuals who are Jk(a-b-) can make anti-Jk3. The Jk(a-b-) phenotype is most commonly seen in individuals of Polynesian, Filipino, or Chinese descent. Anti-Ku may be found in immunized individuals who have the Kell null (K0) phenotype. The K0phenotype is not associated with a specific ethnicity.
All of the following cellular antigens are important to an immunohematologist EXCEPT: The correct answer is highlighted below Blood group antigens Histocompatibility antigens Haptens Autoantigens
The correct answer is haptens. Haptens are immunogens that have a molecular weight less than 10,000 daltons and usually do not elicit an immune response on their own, thus they are not considered clinically significant. Blood group antigens are important in compatibility testing for red blood cell transfusions. Histocompatibility antigens are important for compatibility testing involving nucleated cells. Autoantigens are important for all compatibility testing.
False negative results may occur with indirect antiglobulin tests as a result of all of the following EXCEPT: The correct answer is highlighted below Undercentrifugation Delay in adding antiglobulin reagent Failure to adequately wash cells Red blood cells have a positive DAT
An indirect antiglobulin test (IAT) is used to investigate in-vitro sensitization of red blood cells. Common tests that are IATs include antibody screens, antibody identification, crossmatching, and red blood cell phenotyping. Using cells for an IAT that are already coated with antibody or complement components will cause a false positive result. Addition of the anti-human globulin (AHG) will crosslink the already sensitized red cells leading to agglutination, which is a positive result. Undercentrifugation will reduce antigen-antibody binding causing a false negative result. Delaying the addition of AHG means that the antibody may no longer be bound to the antigen (binding is reversible) on the red cells causing a false negative result. Lastly, not washing well would mean that proteins may be present that can neutralize the AHG causing a false negative result.
HLA antibodies are responsible for which of the following transfusion reactions? The correct answer is highlighted below Allergic transfusion reactions Transfusion-associated sepsis Transfusion-associated circulatory overload Transfusion-related acute lung injury (TRALI)
Antibodies to human leukocyte antigens (HLA) are responsible for transfusion-related acute lung injury (TRALI). The pathogenesis of this transfusion reaction is not fully understood but there are two accepted mechanisms. The first involves antibodies to human leukocyte antigens or human neutrophil antigens transfused into a recipient. The antibodies bind and activate the recipient's leukocytes. The second mechanism involves a patient undergoing some type of event that primes their leukocytes. This includes a disease state, infection, or trauma). The patient is then transfused with a product that contains cytokines or anti-leukocyte antibodies which then activate the already primed leukocytes. Both mechanisms cause leukocytes (especially neutrophils) to aggregate in the lungs. There is damage to the endothelium, which leads to an increase in pulmonary capillary permeability and noncardiogenic pulmonary edema. Allergic reactions are due to a recipient having an antibody (usually IgE) to a protein in the plasma of the donor. They can also be caused by donor antibodies to protein present the recipient's plasma. Transfusion associated sepsis is caused by bacterial contamination of a transfused product. Transfusion associated circulatory overload is caused by the inability of a patient's circulatory system to handle the additional workload from the transfused product. It occurs when the volume or rate of transfusion is too high.
In an emergency release, why do blood bankers seldom encounter patients who have experienced hemolytic transfusion reactions (HTR) from transfusion of uncrossmatched packed RBCs? Select the best response. The correct answer is highlighted below The incidence of unexpected red blood cell antibodies is relatively low. They usually receive group O Rh-negative red blood cells; a hemolytic transfusion reaction will never occur if O Rh-negative red blood cells are transfused. They hemorrhage so severely that incompatible donor red blood cells "bleed out" before a reaction occurs. Some patients have cold-reactive antibodies that will not react at body temperature
Hemolytic transfusion reactions seldom occur due to the relatively low incidence (e.g., 1.64% has been cited in general patient populations) of unexpected clinically significant antibodies in random patients. In emergencies, the need for blood transfusion may exceed the need to complete compatibility testing, especially in cases with patients losing more than 20% of their own blood volume. Being transfused with group O, Rh-negative RBCs is irrelevant in cases where the recipient has an unexpected clinically significant antibody such as anti-K or anti-c. For testing purposes, it is important for pretransfusion samples to be collected prior to transfusion of uncrossmatched blood products. Pre-transfusion testing can be completed after issuance of emergency release units. Incompatible red blood cells may "bleed out" as an adverse effect of blood transfusion. A hemolytic transfusion reaction may occur once the patient's antibody rebounds and destroys remaining antigen-positive donor red cells. me patients can have only cold-reactive antibodies that will not react at body temperature(37°C). However, this does not adequately explain the low number of reported HTRs in emergency release situations.
A 40-year-old female receives two units of Red Blood Cells during a surgical procedure. The patient has no prior history of transfusions. Seven days later, she presents with extensive bruising of the extremities and bleeding of the gums, with no additional symptoms. Her platelet count is 5 x 109/L (reference interval 150 - 400 x 109/L). What is the most likely diagnosis? The correct answer is highlighted below Post transfusion purpura (PTP) Acute hemolytic transfusion reaction (AHTR) Transfusion-related acute lung injury (TRALI) Allergic reaction
Her symptoms, including severe thrombocytopenia one week after transfusion, are most consistent with post-transfusion purpura (PTP). PTP results as an anamnestic response to a platelet antigen. PTP presents 1 to 24 days after a transfusion. PTP is caused by platelet-specific antibodies in a patient who has been previously exposed to platelet antigens through pregnancy or transfusion. The most frequently identified antibody is Anti-PLA1, which reacts with platelet antigen HPA-1a. The platelet antibody binds to the platelet surface, which allows for extravascular removal through the liver or the spleen. The patient's own platelets are destroyed as well, thus aggravating the thrombocytopenia. An acute hemolytic transfusion reaction (AHTR) occurs within 24 hours of a transfusion. Symptoms include fever, chills, back pain, hemoglobinuria, hemoglobinemia, hypotension, renal failure, shock, and DIC. Transfusion-related acute lung injury usually occurs within 6 hours of a transfusion with symptoms that include respiratory distress and severe hypoxemia. Other symptoms can include fever or hypotension. Allergic transfusion reactions also occur within 24 hours of a transfusion. Symptoms that occur with this type of transfusion reaction include weals, hives, erythema, or pruritus.
Which of the following noninfectious complications of blood transfusion is prevented by the irradiation of blood components? The correct answer is highlighted below Anaphylactic reactions Febrile non-hemolytic reactions Transfusion-related acute lung injury (TRALI) Transfusion-associated graft versus host disease (TA-GVHD)
Irradiation prevents proliferation of donor T lymphocytes in blood components. T lymphocytes in blood components may cause TA-GVHD in patients who are immunocompromised, who are receiving components from a blood relative, or who receive HLA-matched components. Washed components or components from IgA-deficient donors are indicated for patients at risk for anaphylactic reactions. The incidence of febrile non-hemolytic reactions has been reduced through the implementation of universal leukoreduction. One mitigation strategy to reduce the incidence of TRALI is to collect components from male donors, female donors who have never been pregnant, or female donors who have been tested since their last pregnancy and are negative for HLA antibodies.
Tube-based agglutination reactions in blood bank are graded from negative (0) to 4+. A reaction that has numerous small clumps in a cloudy, red background is: The correct answer is highlighted below 1+ 2+ 3+ 4+
The correct answer is 1+. A 1+ reaction has numerous small clumps and cloudy red supernatant. A 2+ has many medium-sized clumps and clear supernatant. A 3+ has several large clumps and clear supernatant. A 4+ has one solid clump, no free cells, and clear supernatant.
Which of the prospective donors below would be an acceptable blood donor? The correct answer is highlighted below Donor number 1: Blood pressure: 90/55 Pulse: 105 Temperature: 36.4ºC (97.6 ºF) Donor number 2: Blood pressure: 200/90 Pulse: 72 Temperature: 37ºC (98.6 ºF) Donor number 3: Blood pressure: 110/72 Pulse:66 Temperature: 37.2ºC (99.0 ºF) Donor number 4: Blood pressure: 100/70 Pulse: 98 Temperature: 38.3 (101.0 ºF)
The correct answer is donor number 3. Systolic blood pressure must be less than or equal to 180; diastolic blood pressure must be less than or equal to 100; pulse must be within 50-100 beats per minute; temperature must be less than or equal to 37.5oC (99.5oF).
In order to avoid repeating pretransfusion testing on a neonate during one hospital admission, all of the following must be true, EXCEPT? The correct answer is highlighted below Received only ABO-compatible blood Received only Rh-compatible blood No unexpected antibodies in the serum or plasma Has only received formula for nourishment
The correct answer is has only received formula for nourishment. The neonate's nutrition has no bearing on transfusion requirements. It is unnecessary to repeat pretransfusion testing during any one hospital admission, provided that the infant received only ABO-compatible and Rh-compatible transfusions and had no unexpected antibodies in the serum or plasma.
Lewis Blood Group System is a human blood group unlike most others. The antigen is produced and secreted by exocrine glands, eventually adsorbing to the surface of red blood cells. Its expression is based on the genetic expression of the Lewis and Secretor genes. Based on the following genotype (Le) (Se), what would you predict the Lewis antigen phenotypic expression to be? The correct answer is highlighted below Le(a- b-) Le(a+ b+) Le(a- b+) Le(a+ b-)
The correct answer is: Le(a- b+) A person with a functional Lewis gene (Le) and functional Secretor gene (Se) expresses the phenotype Le(a-b+). The key to answering this question and all others like it, is simply memorizing the following chart: Phenotype Lewis Genotype Secretor Genotype Le(a+b-) Le sese Le(a-b+) Le Se Le(a-b-) lele sese or Se Essentially, a functional Lewis gene codes for the enzyme fucosyltransferase 3, which adds fucose to an oligosaccharide precursor at the penultimate position. Meanwhile, a functional Secretor gene codes for the enzyme fucosyltransferase 2, which adds fucose to an oligosaccharide precursor at the terminal position. If a person has Le expression but is a nonsecretor (sese), he will express a phenotype of Le(a+b-). If a person has Le expression and is also a secretor (Se), he will express a phenotype of Le(a-b+). If a person does not have Le expression (lele), it does not matter if he is a Secretor (Se) or nonsecretor (sese), he will always express the phenotype Le(a-b-).
