[Genotyping for Auxiliary Identification of Anti-C Alloantibody with Anti-f Autoantibody Mimicking Alloantibody]

Objective: To identify the difficult antibody specificity of 1 PNH patient with blood transfusion history by genotyping.

Methods: RH typing of this patient was performed using gel card method, the antibody specificity was identified by panel cells, the RH-unrelated phenotype were excluded by genotyping method in difficult condition of serologic identification, furthmore different RH phenotype cells were used for adsorption-elution so as to re-examine the reactivity of antibodies in this patient's serum, and finally different RH phenotype cells were combined to exclude other unrelated antibodies.

Results: The RH phenotype presented as double population for C antigen, and positive agglutination for the other antigens. The results of RHD zygote, together with RHD and RHCE sequencing showed that the RHD genotype was homozygous RHD/RHD, and the c.122A＞G mutation did not found in RHCE gene, thus C^W antigen was excluded; 48G lies in the 1st exon, the 5th exon showed nt676 G/C heterozygosity, the 2nd-4th, 6th-10th exons did not show mutations, however a new mutation was found in the 4th intron IVS4+29A＞C. It can be judged that the RH genotype was Dce/DcE, and its phenotype should be ccDEe. The anti-C alloantibody and rare anti-f autoantibody mimicking alloantibody in serum was determined by different RH phenotypic cell absorption-elution. Finally, cross-matched AB ccDEE blood units were selected for the patient and there was no adverse reactions of blood transfusion occurred.

Conclusion: Genotyping can be auxiliarily applied to the identification of difficult antibodies in serum of a patient, thereby reducing the risk of blood transfusion.