Kidd

Question 1

Kidd gene (SLC14A1) location

Answer 1

Chromosome 18q11-q12

Question 2

Kidd antigen on treated RBCs

Answer 2

Resistant to proteolytic enzymes (papain, ficin)

Question 3

Kidd antigen location

Answer 3

Human urea transporter 11

Allows urea uptake and prevents RBC shrinkage in hypertonic environment

Question 4

Kidd null phenotype

Answer 4

Jk(a-b-) Jk:-3

Homozygous Silent allele

Relatively common in Polynesians

Question 5

Japanese Jk(a-b-)

Answer 5

Dominant inhibitor gene In(jk)

Very weak expression of antigens detectable by adsorption/elution

Question 6

Kidd phenotype prevalence

White

Answer 6

Jk(a+b-): 26%
Jk(a+b+): 50%
Jk(a-b+): 24%

Question 7

Kidd phenotype prevalence

Blacks

Answer 7

Jk(a+b-): 52%
Jk(a+b+): 40%
Jk(a-b+): 8%

Question 8

Kidd phenotype prevalence

Asian

Answer 8

Jk(a+b-): 23%
Jk(a+b+): 50%
Jk(a-b+): 27%

Question 9

Kidd antigen expression

Answer 9

Well developed at birth

Question 10

Kidd antibodies

Answer 10

Usually IgG

Can bind complement (antigens clustered together on RBC surface)

Clinically significant: HTRs and HDFN

tend to drop to undetectable levels in plasma and may be missed in pretransfusion testing

Question 11

2M urea lysis test

Answer 11

Cheap quick screen for Jk(a-b-)

Normal cells swell and lyse
Jk(a-b-) cells will shrink and shrivel (no hemolysis)