HPA ‐5 typing discrepancy reveals an Ile503Leu substitution in platelet GPI a (α 2 integrin)
2013; Wiley; Volume: 105; Issue: 1 Linguagem: Inglês
10.1111/vox.12019
ISSN1423-0410
AutoresGérald Bertrand, Vincent Jallu, T. Beranger, Frédéric Bianchi, C Casale, Vinciane Dufour, Christophe Chenet, J. Quesne, Corinne Martageix, C. Kaplan,
Tópico(s)Blood disorders and treatments
ResumoBackground and Objectives In fetal/neonatal thrombocytopenia, maternal alloimmunization is diagnosed by the identification of the maternal alloantibody and the offending paternal antigen inherited by the foetus/neonate. Today, for practical reasons, most laboratories perform platelet genotyping instead of phenotyping. Here, we report the case of a human platelet antigen ( HPA )‐5 genotype/phenotype discrepancy observed in a mother who delivered a mildly thrombocytopenic newborn. Materials and methods Platelet antibody detection and platelet phenotyping were performed using the MAIPA assay; platelet genotypes were determined using BeadChip technology (BioArray), PCR ‐ SSP , PCR ‐ RFLP and sequencing. Results Serological investigations revealed the presence of maternal anti‐ GPII b III a autoantibodies. No alloantibodies were detected. No feto‐maternal platelet incompatibility was observed for HPA ‐1 to ‐21. The mother and newborn were genotyped as HPA ‐5aa using BeadChips, but as HPA ‐5a (weak b) with PCR ‐ SSP and HPA ‐5ab with PCR ‐ RFLP . Mother's platelets were phenotyped as HPA ‐5b(+). GPI a exon 13 sequencing confirmed the HPA ‐5ab genotype of the mother and newborn, and revealed an NM _002203.3:c.1594A>C mutation near the HPA ‐5 polymorphism (5′ side), leading to an I503L amino acid change. Conclusion Feto‐maternal alloimmunization was ruled out: the neonatal thrombocytopenia probably resulted from maternal anti‐ GPII b III a autoantibodies. This case highlights that platelet typing should be performed using two different methods to avoid false diagnosis.
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