Blood Bank Genetics Questions

What is the most common inheritance pattern for blood group antigens?

Autosomal codominant

What term describes alternate forms of a gene that occur at a single chromosome locus

Alleles

What term describes the inheritance of two of the same alleles from each parent?

Homozygous

You performed a population study on your class and found that 84% are D-positive. Using the Hardy-Weinberg equation, determine the percentage of your classmates that are heterozygous for the D antigen.

48%

The dominant allele E and recessive allele e exist in a total random population, where the frequency of e is 20%. What would the total percentage of the population be that are homozygous for the e allele?

4%

Following antibody identification your patient is found to have anti-K, anti-Jk^a, and anti-E. How many RBC units do you need to type to find 2 antigen-negative RBC units? Show your work.

The antigens occur in the donor population with the following frequencies: E = 30%, K = 9%, Jk^a = 77%.

13-14 RBC Units need to be tested

Which of the following is provided by hemagglutination serologic testing for red cell antigens

Phenotype

RBC genotyping is used

To confirm serological testing

When serology is not possible

When serology is not sensitive enough or discrepancies occur

All of the above

Preseroconversion window

Is the time when donors can be infected but do not yet test positive by serologic methods

May be narrowed by using molecular methods

Refers mainly to viral pathogens

All of the above

Most blood group antigens are the result of

Single nucleotide polymorphisms

In relationship testing, what is the criterion for direct exclusion

Genetic marker is present in the child but absent in both the mother and the alleged father

Historically, relationship testing assumed maternity and excluded paternity by either indirect or direct exclusion.

Given the following results for the codominant Rh antigen pair of E and e, which of the following conclusions can be made?

	Mother	Alleged Father	Child
Phenotype	E+ e+	E- e+	E+ e-

(+ means antigen is detected; - means antigen is not detected)

The father can be indirectly excluded because the child did not inherit the e antigen