A prospective study on the prevalence of neonatal alloimmune thrombocytopenia with maternal and neonatal human platelet antigen genotypic profiling

BACKGROUND: Neonatal alloimmune thrombocytopenia (NAIT) results due to the human platelet antigen (HPA) incompatibility between the mother and the fetus, which in turn leads to maternal alloimmunization against fetal platelet antigen. In view of the lack of a defined protocol for its diagnosis and management, it is important to identify at-risk patients with the help of new noninvasive methods and prevent fetal complications. AIM: The aim of our study was to evaluate the suspected cases of NAIT so as to determine its prevalence and formulate an appropriate algorithm for its diagnosis and management in our setup. MATERIALS AND METHODS: Thrombocytopenic neonates from neonatal services were included in the study between May 2018 and March 2020. An algorithm was designed to evaluate the suspected cases of NAIT, which involved the clinical assessment of the neonate and maternal HPA antibody screening and compatibility test with the neonatal platelet antigens by maternal serum on a solid phase red cell adherence assay system by Immucor, Norcoss A, USA. In addition, genotypic analysis was done to find out the implicated HPA antigens present in the neonate, causing NAIT. The genotypic assessment was done using the Link Seq HPA Typing Kit, by One Lambda, and real-time polymerase chain reaction. RESULTS: Out of 6237 neonates screened for eligibility, we found 1143 neonates to be thrombocytopenic. Out of 1143 thrombocytopenic neonates, we diagnosed NAIT in 10 neonates, giving a prevalence of 0.8% in thrombocytopenic neonates and 0.16% in the total enrolled neonates. CONCLUSION: The prevalence of NAIT in neonates with thrombocytopenia was 0.8%, and 0.16% in the total admitted neonates. HPA-3b, Hpa-9b and HPA-15b were found to be the most commonly implicated antigens leading to thrombocytopenia in the neonates, in our population