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Describe Autosomal Dominant trait
- Affects every generation.
- Affects both male and female equally
Describe Autosomal Recessive
- Skips a generation
- Affects only both children equally
Describe X linked dominant
- Affects every generation
- Only affects daughters (all daughters will have trait)
Describe X linked recessive
- Skips a generation
- The father always expresses the trait but never passes it on to his sons BUT always passes it on to his daughters. Women can pass to their sons.
Classic example is the inheritance of hemophilia A.
How do you get the pecentage of the population that would have compatible cells for a patient?
- you multiply the percentages together. ie:
- anti K (91% compatible) & anti Jka (23% compatible) are pressent. You .91x.23 = 21%
A patient has an antibody (Anti-K). The phenotype frequncy of Anti-K is 65%. How many units would you need to test to find 2 units of PRBC's that are negative for the antigen corresponding to the anitbody the patient has?
- You first have to get the % compatible. Which is 100 - phenotype % freq (.65) = 35%.
- Now you need to divide 2(#of units)/.35 = 5-6 units that need screened.
How do you find % compatible if you only have Phenotype frequency percentage or vice versa?
- Subtract 100 from the Phenotype % frequency = % compatible
- Subtract 100 from % compatible = % pheno freq.
What is the purpose of the IAT test?
To detect IgG or complement (C3d) in vitro
What is the purpose of the DAT?
for the detection of IgG and/or C3d in vivo
When would a DAT be positive
- HDN - Infant cells are coated with mother IgG antibody
- Transfusion reation - Recipient antibody is coating donor cells (only one with mixed field reaction)
- Autoimmune hemolytic anemia - Auto antibody is coating patients own cells
- Drug induced hemolytic anemia - Antibody to drug - drug coating patients cells.
When do you perform an IAT
- Compatiblity testing
- Antibody ID
- Antigen Typing
What are the 2 stages of hemagglutination?
Sensitization - Physical attachment of an antibody to red cell antigens.
Agglutination - Multiple antigen antibody bridges to connect adjacent red cells forming agglutination
Sensitized red cells crosslink.
What causes hemagglutination
- Ab/Agn ratio
- pH (most react best at 6.5-7.5)
- Incubation Time
- Immunoglobulin Class (IgM is a good direct agglutin & IgG usually need AHG)
- # of antigens present
- Location of antigens
- Zeta potential
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