WEEK 3: Rh Blood Group and Haemolytic Disease

Question 1

The Rh system comprises of how many commonly occurring antigens?

Answer 1

5

Question 2

what is the most important antigen of the Rh system?

Answer 2

D

Question 3

which chromosome is the RhD gene found on?

Answer 3

chromosome 1

Question 4

how many people are RhD positive in the Uk?

Answer 4

85%

Question 5

how many people are RhD negative in the Uk?

Answer 5

15%

Question 6

what are 2 variations of the RhD blood group?

Answer 6

weak D and partial D

Question 7

what is weak D?

Answer 7

possess all normal D antigens but have quantitatively less. Cannot produce anti-D

Question 8

what is partial D?

Answer 8

lacks part of a normal D antigen. Therefore can produce anti-D

Question 9

what are the 5 commonly occurring antigens does the rh system compose of?

Answer 9

D, C, c, E, e

Question 10

what antigens are alleles of each other from the Rh system?

Answer 10

C and c
E and e

Question 11

what gene are alleles C, c, E and e on?

Answer 11

RHCE gene

Question 12

what is the major cause of haemolytic disease of the fetus and newborn?

Answer 12

anti-D

Question 13

how is HDFN produced in women?

Answer 13

as a result of sensitisation by red cells from D positive fetus

Question 14

how is HDFN produced in men?

Answer 14

as a results of transfusion with D positive blood

Question 15

can anti-c cause HDFN?

Answer 15

yes

Question 16

can anti-E cause HDFN?

Answer 16

yes but less significant than c

Question 17

what is HDFN?

Answer 17

condition affecting fetuses and newborn infants caused by a blood group antibody in the mother attacking red cells in the infant which carry the corresponding antigen inherited from the father

Question 18

when is HDFN most potent?

Answer 18

when the mother is RhD negative and the fetus is RhD positive

Question 19

why do Rh antigens cause HDFN and not ABO antigens?

Answer 19

Rh antigens are fully developed at birth but ABO arent

Question 20

how is HDFN diagnosed?

Answer 20

direct antiglobulin test on cord blood. This detects IgG antibody bound to the surface of the infants rbcs

Question 21

how is mild HDFN treated?

Answer 21

phototherapy under UV light. Breaks down bilirubin into biliverdin, which is water soluble. Pee it out

Question 22

how is moderate HDFN treated?

Answer 22

top up or exchange tranfusion

Question 23

how is severe HDFN treated?

Answer 23

exchange transfusion at birth or intra-uterine transfusion during pregnancy

Question 24

what are some requirements for IUT?

Answer 24

5 days old or less
sickle cell negative
negative for rbc antibodies
low level of anti-A and anti-B

Question 25

how is HDFN prevented?

Answer 25

give the mother anti-D