Severe Hemolytic Disease of the Newborn Caused by Anti-M Antibodies

Anti-M′s are naturally occurring antibodies described by Wolff and Johnsson in 1933. They have been rarely associated as cause of diseases with different degrees of severity as intrauterine deaths or hemolytic disease of the newborn HDN[1, 2]. The detection of anti-M in antenatal screening is a rare finding[3]. High titers of IgG and IgM anti-M are responsible for neonatal red cell aplasia and HDN. The MNSs blood group system is considered to be clinically insignificant as it only reacts at temperatures below 37 °C and appears to be more common in infants than in adults. MN antibodies do not usually cause severe hyperbilirubinemia. A review of seven cases of patients with auto anti-M antibodies reported a varied degree of symptoms[4]. In a study carried out to detect the prevalence of alloantibodies among 3.577 multigravida women in India, only one was anti-M positive by column agglutination technology[5].