title: A case of dispermic chimerism with normal phenotype identified during ABO blood grouping.
abstract: BACKGROUND
  Human chimerism with normal phenotype derived from the fusion of two different zygotes is a rare phenomenon. We describe a case of a phenotypically normal 17-year-old diagnosed with dispermic chimerism during routine ABO blood grouping.
  
  
  METHODS
  ABO grouping, ABO genotyping, karyotyping, human leukocyte antigen (HLA) typing, and short tandem repeat (STR) analysis were performed.
  
  
  RESULTS
  Forward typing with anti-A and anti-B sera resulted in mixed-field agglutination of red blood cells. The mother and father were blood group O and AB, respectively. The proposita had O1, A201 and B alleles in the ABO locus; O1 was a maternal allele, while A201 and B were the paternal alleles. The proposita karyotype was 46,XX/46,XY. HLA typing revealed that the proposita had three alleles (46, 51, 54) at the HLA-B locus, with the additional allele of paternal origin. STR analysis identified three alleles for five of the 15 markers (D2S1338, TPOX, D8S1179, D19S433, and D21S11) analyzed in the proposita's blood- and skin fibroblast-derived DNA. The additional alleles of TPOX, D8S1179, and D21S11 were of paternal origin.
  
  
  CONCLUSIONS
  The genetic findings suggest that this proposita was produced by dispermic fertilization of two identical haploid ova formed by parthenogenetic activation.
authors.forename: Pei-Yuan
authors.initials: PY
authors.lastname: Zhu
authors.forename: Jing-Mei
authors.initials: JM
authors.lastname: Yan
authors.forename: Min
authors.initials: M
authors.lastname: Xue
authors.forename: Dong
authors.initials: D
authors.lastname: Ye
authors.forename: Gen-Hong
authors.initials: GH
authors.lastname: Yao
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Luan
mesh_terms: D000017:ABO Blood-Group System / Q000097:blood*; D000293:Adolescent; D001788:Blood Grouping and Crossmatching; D002678:Chimera / Q000097:blood*; D005260:Female; D006801:Humans; D018895:Microsatellite Repeats; D010641:Phenotype
chemical_list: D000017:ABO Blood-Group System