title: Molecular genetic analysis and structure model of a rare B(A)02 subgroup of the ABO blood group system.
abstract: BACKGROUND
  Serological analysis of ABO blood group has been widely applied in transfusion medicine. However, ABO subgroups with different expression of blood group antigens sometimes cannot be determined by serological methods. Therefore, genotyping is useful to understand the variant ABO phenotypes.
  
  
  METHODS
  Exon 6 to exon 7 and adjacent introns of the ABO gene from a donor with ABO typing discrepancy were amplified and sequenced. Cloning sequencing was also performed to identify the allele. To explore the effect of mutation, three dimensional model of mutant p.Pro234Ala was built and optimized.
  
  
  RESULTS
  The variant B (c. 700C > G) allele expressed an AweakB phenotype with anti-A in his serum with a ABO*B(A)02/O02 heterozygote genotype. Cloning sequencing confirmed that the c.700C > G single nucleotide polymorphism was associated with a B101 allele. Three dimensional molecular modeling suggested that p.Pro234Ala might affect the conformation of His233, Met266 and Ala268, which were known as critical residues for donor recognition.
  
  
  CONCLUSIONS
  ABO genotyping is needed for correct identification subgroups to improve accuracy evaluation of blood typing and increase the safety of blood transfusion. Alteration of DNA sequence in the ABO gene resulted in amino acid substitutions and led to a weak or missing expression of ABO antigens.
authors.affiliation: Jiangsu Province Blood Center, Nanjing 210042, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Chen
authors.affiliation: The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Science, Nanjing University, Nanjing 210093, China.
authors.forename: Jiahuang
authors.initials: J
authors.lastname: Li
authors.affiliation: Jiangsu Province Blood Center, Nanjing 210042, China.
authors.forename: Jianyu
authors.initials: J
authors.lastname: Xiao
authors.affiliation: Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Science, Peking Union Medical College, Nanjing 210042, China.
authors.forename: Leilei
authors.initials: L
authors.lastname: Du
authors.affiliation: Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Science, Peking Union Medical College, Nanjing 210042, China.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008, China. Electronic address: yaogenhong@126.com.
authors.forename: Genhong
authors.initials: G
authors.lastname: Yao
mesh_terms: D000017:ABO Blood-Group System / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D000328:Adult; D000483:Alleles; D019943:Amino Acid Substitution; D004252:DNA Mutational Analysis; D005786:Gene Expression Regulation; D060005:Genotyping Techniques; D006801:Humans; D008297:Male; D008958:Models, Molecular; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary
chemical_list: D000017:ABO Blood-Group System
keywords: ABO blood group system; ABO discrepancy; ABO genotyping; B(A)