Fetal genotyping for platelets antigens: a precise tool for alloimmune thrombocytopenia: case report and literature review
ABSTRACT Maternal-fetal alloimmune thrombocytopenia complicates about 0.1% of all pregnancies and is associated with major fetal and neonatal morbidity and mortality, especially spontaneous central nervous system bleeding leading to death and neurological handicaps. Successful prevention and treatment depend on the identification of at-risk possible carriers of anti-platelet antibodies.
We report a case of a mother with a previous child that developed neonatal hemorrhage; HPA-5b anti-platelet antibodies were detected post-natally. During the next pregnancy, fetal genotyping confirmed the presence of HPA-5b antigen; she was treated with weekly intravenous human immunoglobulin and oral prednisone. Pregnancy evolved without remarkable features and a full-term baby was delivered, with normal platelet counts.
Fetal alloimmune thrombocytopenia is a potentially lethal condition, but early detection and prevention lead to successful outcome in most cases.
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ABSTRACT: Neonatal alloimmune thrombocytopenia (NAT) is a life-threatening bleeding disorder caused by maternal platelet antibodies produced in response to fetal platelet antigens inherited from the father. Antiplatelet antibodies cross the placenta and cause destruction of fetal platelets, leading to severe thrombocytopenia, and potentially bleeding, including fatal intracerebral hemorrhage. Incompatibilities between maternal and fetal platelets for the human platelet antigen 1a (previously called PL(A1)) account for most of the patients with NAT, but other antigens are commonly implicated. Diagnostic testing for NAT involves genotyping of maternal, paternal, and sometimes fetal DNA; platelet antigen phenotyping; and maternal platelet antibody investigations using specialized platelet glycoprotein specific assays. The management of women and infants at risk for NAT remains largely empiric; and mounting evidence points to prohibitive risks of invasive procedures such as fetal blood sampling and intrauterine platelet transfusions, except in rare circumstances. Improvements in our understanding of the pathophysiology of NAT, and of clinical and laboratory predictors of severity, may help develop better treatments and improve our ability to identify mothers at risk.Transfusion medicine reviews 11/2008; 22(4):255-67. DOI:10.1016/j.tmrv.2008.05.003 · 4.54 Impact Factor
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ABSTRACT: Serological and clinical data were collected in 348 cases of suspected neonatal alloimmune thrombocytopenia (NAT). Of the 144 mothers who were Zwa-negative, 107 had Zwa antibodies--alone (94); with HLA antibodies (12); or with Bra antibodies (1). Antibodies were detected in 12 of the 204 Zwa-positive mothers as follows: anti-Bra (9), anti-Zwb (1), anti-Baka with HLA antibody (1), and blood group B isoagglutinins (1). The frequency of NAT due to Bra incompatibility (19%) was second to Zwa (78%). Zwa-NAT was clinically the more severe (14% had intracranial haemorrhages) and responded well to either maternal platelet transfusions or intravenous IgG. In Bra-NAT intracranial haemorrhages were not observed and most children recovered without specific therapy.The Lancet 03/1989; 1(8634):363-6. DOI:10.1016/S0140-6736(89)91733-9 · 39.21 Impact Factor
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ABSTRACT: Two families are presented, where the mothers have given birth to children with neonatal alloimmune thrombocytopenia (NAITP) due to immunization towards the platelet specific antigen PIA1, which is responsible for most of the cases with NAITP. Anti-PIA1 has previously been difficult to demonstrate, but current techniques, such as the platelet suspension immunofluorescence test (PSIFT) used here, have made routine laboratory diagnosis possible. Both mothers in these families were HLA-B8 positive. This antigen shows strong association with PIA1 immunization.Acta paediatrica 08/1983; 72(4):583-7. · 1.77 Impact Factor