WEEK 3: Rh Blood Group and Haemolytic Disease Flashcards
The Rh system comprises of how many commonly occurring antigens?
5
what is the most important antigen of the Rh system?
D
which chromosome is the RhD gene found on?
chromosome 1
how many people are RhD positive in the Uk?
85%
how many people are RhD negative in the Uk?
15%
what are 2 variations of the RhD blood group?
weak D and partial D
what is weak D?
possess all normal D antigens but have quantitatively less. Cannot produce anti-D
what is partial D?
lacks part of a normal D antigen. Therefore can produce anti-D
what are the 5 commonly occurring antigens does the rh system compose of?
D, C, c, E, e
what antigens are alleles of each other from the Rh system?
C and c
E and e
what gene are alleles C, c, E and e on?
RHCE gene
what is the major cause of haemolytic disease of the fetus and newborn?
anti-D
how is HDFN produced in women?
as a result of sensitisation by red cells from D positive fetus
how is HDFN produced in men?
as a results of transfusion with D positive blood
can anti-c cause HDFN?
yes
can anti-E cause HDFN?
yes but less significant than c
what is HDFN?
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
when is HDFN most potent?
when the mother is RhD negative and the fetus is RhD positive
why do Rh antigens cause HDFN and not ABO antigens?
Rh antigens are fully developed at birth but ABO arent
how is HDFN diagnosed?
direct antiglobulin test on cord blood. This detects IgG antibody bound to the surface of the infants rbcs
how is mild HDFN treated?
phototherapy under UV light. Breaks down bilirubin into biliverdin, which is water soluble. Pee it out
how is moderate HDFN treated?
top up or exchange tranfusion
how is severe HDFN treated?
exchange transfusion at birth or intra-uterine transfusion during pregnancy
what are some requirements for IUT?
5 days old or less
sickle cell negative
negative for rbc antibodies
low level of anti-A and anti-B
how is HDFN prevented?
give the mother anti-D
