title: The serological and genetic characterization of CisAB blood group in a Chinese family.
abstract: BACKGROUND
  The rare CisAB blood genotype results in the inheritance of both the A and B blood types from a single parent. Several CisAB blood type phenotypes have been characterized that differ in their serological reactions and in the activities of the gene-encoded blood group A and B transferases. In this study, we conducted serological and genetic analyses of a Chinese family with four CisAB-carrying members.
  
  
  METHODS
  A 10-year-old girl was suspected to have the CisAB blood type when forward blood typing indicated that she was blood type AB but reverse blood typing indicated that she was blood type A. An examination of this family identified that four of ten family members across three generations had a pattern of AB inheritance that could be explained only by the inheritance of the CisAB genotype. Blood samples from the family were tested serologically and genetically using PCR-SSP for the relevant CisAB alleles. The samples that were suitable for DNA analysis were sequenced for potential mutations.
  
  
  RESULTS
  Of the ten family members included in this study, four members showed mismatched forward and reverse blood grouping results, four members typed as blood group O and the remaining two members typed as blood group B. Among the four mismatched individuals, the propositus and her mother's mother were serologically typed as having the A2B3 phenotype. The propositus' mother and her mother's brother were typed as having the A2B phenotype, and had the genotypes CisAB01/O02 and CisAB01/B101, respectively. Further sequencing analysis of the four samples with the CisAB blood type revealed that a G(261) deletion occurred along with 297A>G, 467C>T, 646T>A, 681G>A, 771C>T, 803G>C and 829G>C substitutions in exons 6 and 7 of CisAB01/O02, while a 297A>G substitution occurred in exon 6 and 467C>T, 803G>C, 526C>G, 657C>T, 703G>A, 796C>A, 930G>A substitutions occurred in exon 7 of CisAB01/B101.
  
  
  CONCLUSIONS
  A family was identified in which 4/10 family members across three generations had inherited the CisAB blood group. Two of the CisAB genotypes were further identified as CisAB01/O02 and CisAB01/B101. The CisAB heterozygous alleles contributed to the different phenotypes that were observed.
authors.affiliation: Department of Blood Transfusion, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China; Department of Blood Transfusion, Beijing Tsinghua Changgung Hospital, Medical Center, Tsinghua University, Rd Middle, Haidian, Beijing, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Department of Hematology, Beijing Tiantan Hospital, Capital Medical University, No. 6, Tiantan Xili, Dongcheng District, Beijing 100050, China.
authors.forename: Tianhong
authors.initials: T
authors.lastname: Miao
authors.affiliation: Department of Hematology, Beijing Tiantan Hospital, Capital Medical University, No. 6, Tiantan Xili, Dongcheng District, Beijing 100050, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Yan
authors.affiliation: Department of Hematology, Beijing Tiantan Hospital, Capital Medical University, No. 6, Tiantan Xili, Dongcheng District, Beijing 100050, China. Electronic address: yuanbol@ccmu.edu.cn.
authors.forename: Yuanbo
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics*; D044466:Asian People; D001483:Base Sequence; D002648:Child; D002681:China; D005260:Female; D005838:Genotype; D006801:Humans; D017354:Point Mutation; D017384:Sequence Deletion
chemical_list: D000017:ABO Blood-Group System
keywords: CisAB; DNA sequencing; Genotype; Phenotype