What's with the boys? Lower birth weight in boys from HPA-1a alloimmunized pregnancies - New insights from a large prospective screening study in Poland.

Fetomaternal incompatibility in human platelet antigens (HPAs) can cause maternal alloimmunization, which in turn may lead to thrombocytopenia with or without intracranial hemorrhage (ICH) in the fetus or newborn. Retrospective studies suggest that boys from alloimmunized mothers may have higher risk of ICH and lower birth weight than girls. The objective of this study was to assess how maternal HPA-1a alloimmunization, sex of the neonate and birth weight relates in a large prospective cohort. Through a national screening study in Poland (PREVFNAIT) involving HPA-1 typing of 24,259 pregnant women during 2013-2017, 606 HPA-1a negative pregnant women and their offspring were identified and included. Various multivariate models were used to assess if and how maternal HPA-1a alloimmunization status was associated with birth weight and risk of having a small for gestational age (SGA) neonate, and if and how sex of the neonate mattered. Most immunized pregnancies had male fetuses (69 %). Women carrying a male fetus had increased likelihood of having an SGA newborn if they were HPA-1a alloimmunized compared to non-immunized mothers. Increasing maternal anti-HPA-1a antibody levels were significantly associated with reduced birth weight and SGA risk among male-fetus pregnancies, but not if the fetus was female. In conclusion, anti-HPA-1a antibodies in a male fetus pregnancy is associated with increased risk of SGA and lower birth weight, especially if the antibody level is high. Sex of the fetus may therefore be considered as a new clinical predictor of more severe FNAIT neonatal outcome.

A high prevalence of neutrophil-specific antibodies in ELANE-mutated severe congenital neutropenia.

An assay for neutrophil-specific antibodies is frequently used in the workup of chronic severe neutropenia and is suggestive of autoimmune, or sporadically alloimmune neutropenia, rather than severe congenital neutropenia (SCN). We analyzed a neutropenia consortium database for the outcomes of antibody testing initiated before receiving genetic diagnosis in Polish SCN cohort. Test results, performed in a single reference laboratory, were available for 14 patients with ELANE-mutated SCN or cyclic neutropenia, and were frequently positive (36%). We note that the trigger for genetic studies in severe neutropenia should not be affected by antibody-positivity and should be clinically driven.