Single point mutation in human glycoprotein IIIa is associated with a new platelet-specific alloantigen (Mo) involved in neonatal alloimmune thrombocytopenia

Abstract

Here we describe a new platelet-specific alloantigen that was identified in a case of neonatal alloimmune thrombocytopenia. This antigen has provisionally been called “Mo.” By studying the Mo family, it was shown to be inherited in an autosomal dominant manner. Immunoprecipitation and Western blot analysis showed that the antigen resides on platelet glycoprotein IIIa (GP IIIa). Genomic analysis, performed by applying polymerase chain reaction and sequencing, showed a C-->G substitution of base pair 1267 of the coding region of the DNA for GP IIIa, resulting in a substitution of Proline407 by Alanine407. That this substitution is associated with the antigen could be demonstrated by restriction fragment length polymorphism analysis of cDNA, prepared from platelet RNA, and of genomic DNA. It was confirmed by dot-blot hybridization with allele-specific oligonucleotides. All family members, also those being Mo antigen-positive, were healthy. None of them appeared to suffer from increased tendency of bleeding or thrombosis. Thus, the Mo mutation does not lead to significant platelet dysfunction in vivo with heterozygous carriers. One of 450 random healthy blood donors who were tested was positive for the Mo antigen. Typing was performed by the classical serologic methods as well as by DNA analysis.

Neonatal alloimmune thrombocytopenia associated with maternal‐fetal incompatibility for blood group B

“…Assignment of PLT antigen genotypes was made with a customized software program developed by Eragen. Typing for mutations encoding low‐frequency antigens of the HPA‐7, ‐8, ‐10 to ‐14, and ‐16 systems was done by PCR amplification of exons known to contain the relevant mutations 20‐26 . PCR primers corresponding to intronic sequence surrounding exons of interest were designed to yield PCR products ranging from 500 to 1900 nucleotides in length.…”

HPA polymorphism in sub‐Saharan African populations: Beninese, Cameroonians, Congolese, and Pygmies

“… DNA was extracted from buffy coat by salting‐out method (25). HPA genotyping was determined by PCR‐RFLP: HPA‐1 (24), HPA‐2 and HPA‐3 (26), HPA‐5 (27), HPA‐6 (28), HPA‐7 (29), HPA‐9 (30), HPA‐10 (31), HPA‐11 (32), HPA‐15 (21), and/or PCR‐SSP (33). Statistical analyzes were made using software package HLAStat2000 (Busson M. Programme HLAStat INSERM U 396 Immunogénétique Humaine 1996.…”

New platelet glycoprotein polymorphisms causing maternal immunization and neonatal alloimmune thrombocytopenia

“…Low‐frequency PLT alloantigens shown to cause maternal immunization leading to NAIT include those now designated HPA‐4b; 24,25 HPA‐6bw; 26,27 HPA‐7bw; 28 HPA‐8bw; 29 HPA‐9bw; 30 HPA‐10bw; 31 HPA‐11bw; 32 HPA‐12bw; 33 HPA‐13bw; 34 HPA‐14bw; 35 HPA‐16bw; 36 HPA‐17bw; 37 HPA‐18bw; 38 HPA‐19bw, ‐20bw, and ‐21bw; 10 HPA‐22bw; 39 Swi; 13 and Cab2 14 . The two new antigens described here bring the total to 21.…”