The ABO and rhesus blood groups in Perthes' disease.

Determinations were carried out of the ABO blood groups and Rhesus phenotypes of a series of 142 children with Perthes' disease. Where possible their parents and sibs were also grouped. Sera from the mothers of affected children were examined for the presence of Rhesus antibodies. No apparent association was demonstrated between Perthes' disease and any ABO phenotype. The disease is also apparently independent of ABO incompatibility between mother and child. There is the suggestion in these families of an increased incidence of the Rhesus cc phenotype among the affected children. The level of significance is estimated at 0.02, even after taking into account the numerous significance tests possible on the data. Parental and sibship studies show that any association between Perthes' disease and the Rhesus Cc phenotypes, if one does exist, is unlikely to be the product of genetical stratification within the population. Maternal Rhesus antibody, acting through the agency of haemolytic disease of the newborn, plays no detectable part in the aetiology of a subsequently developing Perthes' disease in the child.