[Neonatal blood group incompatibility due to anti-M antibodies]. / Neonataal bloedgroepantagonisme door anti-M-antistoffen.

Neonatal blood group antagonism due to anti-M antibodies is extremely rare. The case is reported of a neonate with moderately severe haemolytic anaemia due to anti-M which required two blood transfusions. Although anti-M antibodies are as a rule regarded as clinically irrelevant, and although they react almost exclusively at lower temperatures, they may in exceptional cases be demonstrated at 37 degrees C, as in the patient described; they may then cause haemolysis. Most strikingly, the direct Coombs test in this patient was negative; this phenomenon has been described before. In unexplained haemolytic anaemia of a newborn, even in the presence of a negative direct Coombs test, the possibility of blood group antagonism should be considered.

A new, low-incidence red cell antigen (HOFM), associated with depressed C antigen.

A case of mild hemolytic disease of the newborn is presented which was caused by an antibody to a hitherto unknown antigen of low incidence. This antigen, now designated as HOFM (ISBT number 700050) was detected in 6 relatives, and in all of them, it was associated with an unusually weakened expression of C antigen. The serological data indicate that HOFM may be part of the Rh system, but the genetic data, although supportive of this interpretation, are inconclusive.