Erythroblastosis

Rh incompatibility may occur when an Rh negative mother carries an Rh-positive fetus. At the time of delivery, a small amount of the baby s Rh-positive blood may gain access to the maternal circulation. In response, the immune system of the mother produces anti-Rh antibodies. During the subsequent pregnancy, the fetus is exposed to these antibodies as they cross the placenta. If this fetus is also Rh-positive, then the anti-Rh antibodies attack the fetal erythrocytes and cause hemolytic disease of the newborn (erythroblastosis fetalis). This may occur in about 3% of second Rh-positive babies and about 10% of third Rh-positive babies. The incidence continues to increase with subsequent pregnancies. 

Avian erythroblastosis virus erbB Receptor for growth factor tyrosine kinase activity... 

The rhesus D antigen occurs in 84% of all white individuals, who are therefore Rh-pos-itive. If an Rh-positive child is born to an Rh-negative mother, fetal erythrocytes can enter the mother s circulation during birth and lead to the formation of antibodies (IgG) against the D antigen. This initially has no acute effects on the mother or child. Complications only arise when there is a second pregnancy with an Rh-positive child, as maternal anti-D antibodies cross the placenta to the fetus even before birth and can trigger destruction of the child s Rh-positive erythrocytes [fetal erythroblastosis). 

Frykberg, L., S. Palmieri, H. Beug, T. Graf, M.J. Hayman, and B. Vennstrom, Transforming capacities of avian erythroblastosis virus mutants deleted in the erbA or erbB oncogenes. Cell, 1983. 32(1) 227-38. 

Hayman, M.J., G.M. Ramsay, K. Savin, G. Kitchener, T. Graf, and H. Beug, Identification and characterization of the avian erythroblastosis virus erbB gene product... 

Vennstrom B, Bishop JM. Isolation and characterization of chicken DNA homologous to the two putative oncogenes of avian erythroblastosis virus. Cell 1982 28 135-143. 

Bilirubin, but not the conjugated pigments, has an affinity for brain tissue (B5, C2, W3), and in newborn infants, with high plasma bilirubin levels due to erythroblastosis or prematurity, staining of the brain nuclei may occur. This causes brain damage and subsequent neurological difficulties, a detailed account of which is given in a review by Claireaux et al. (C3). 

The use of the icterus index, as described by Meulengracht, for the assessment of jaundice has fallen into disrepute because of the errors caused by the presence of lipochromes, carotenoids, and other yellow pigments. Josephson (J6) in his survey found that the correlation coefficient between icterus index and serum bilirubin concentration was 0.69 in 360 healthy subjects and 0.84 in 40 jaundiced subjects. In newborn infants however, bilirubin is the only yellow pigment likely to be present and the possibility of determining serum bilirubin concentrations by direct measurement has again been re-examined. Abelson and Boggs (Al) diluted serum from infants with erythroblastosis 1 in 50 and studied the absorption curves. They found that in addition to the bili-... 

Al. Abelson, N. M., and Boggs, T. R., Plasma pigments in erythroblastosis fetalis. I. Spectrophotometric absorption patterns. Pediatrics 17, 452-460 (1956). 

In fact, when the primary structure of the first steroid receptor, the human glucocorticoid receptor [79] was deduced from the nucleotide sequence the homology of this central region with the product of the v-erb-A oncogene of the avian erythroblastosis virus immediately became conspicuous [80]. This similarity subsequently led to the identification of c-erb-A, the cellular counterpart of v-erb-A, as the gene for a thyroid hormone receptor [92,93]. The kinship amongst these sequences has also greatly helped to identify cDNA clones for other steroid hormone receptors. 

ERB A and B are genes originally found in an avian erythroblastosis virus. ERB A is fused to ERB B. ERB B encodes a truncated EGF-receptor. 

Acute leucosis, chronic lymphadenosis, chronic myelosis, erythroblastosis, haemolytic anaemias, Werlhof s disease, osteomyelosclerosis, polycyth-aemia vera, thalassaemia, shunt hyperbilirubin-aemia, etc. 

Rh-erythroblastosis occurs in 0.2%o and ABO erythroblastosis in 0.6% of all pregnancies. In clinical terms, the course of the latter disease is usually more moderate. Due to severe haemolysis, unconjugated bilirubin levels rise rapidly, often reaching relatively high values. Therapy includes phototherapy, exchange blood transfusions and administration of immunoglobulin (500 mg/kg BW). 

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