Any condition resulting in the
abnormal destruction of
fetal blood products, but commonly refers to
Rh incompatibility between a
mother and
fetus. In the
Rh incompatibility
type of
hemolytic disease of the newborn, some
infants who can break down
red blood cells coated with
maternal antibody into
hemoglobin and then into
indirect bilirubin may lack the final
enzyme necessary to convert the latter into harmless, excretable
bilirubin; bilirubin thus accumulates in toxic amounts in
brain tissues, causing
kernicterus and
jaundice (see
Rhesus isoimmunization;
aka erythroblastosis fetalis). The ABO
form of
HDN also results in destruction of the
erythrocytes of a
fetus, a condition roughly twice as
common as the Rh-incompatibility
form of
HDN, but is almost always clinically milder in its manifestation, and is caused by some of the smaller anti-A or anti-B antibodies in a
mother’s immune system that can permeate the
placental membranes, causing
jaundice,
anemia, and an enlarged liver and
spleen.
HDN can also be a
clinical feature of the Diego, Duffy, Kell-Cellano, and Gerbich
blood groups. are also responsible for other hemoglobinopathies.
See
fetal hemoglobin,
hereditary persistence.
Cf. thalassemia.