title: The AQP1 mutation c.601delG causes the Co-negative phenotype in four patients belonging to the Romani (Gypsy) ethnic group.
abstract: BACKGROUND
  The Colton blood group antigens Co(a), Co(b) and Co3 are encoded by the AQP1 gene which produces a water channel forming integral protein. The extremely rare Co-deficiency enables immunisation against the Co3 isoantigen.
  
  
  METHODS
  Four patients from different regions of Europe who belong to the ethnic minority of Romani (Gypsy) presented with irregular antibodies against a high frequency red blood cell antigen. Positive cross-matches with all red blood cells tested were reported. An Anti-Co3 antibody was identified as the cause of incompatibility in the four cases. The genetic background was determined by polymerase chain reaction typing with sequence-specific primers and by DNA sequencing.
  
  
  RESULTS
  The Co(a-b-) phenotype was confirmed in the four patients despite the fact that genotyping revealed the CO*01 allele of the AQP1 gene. A homozygous AQP1 c.601delG mutation, leading to a frame shift and producing a premature stop in the next codon, was responsible for the Co-negative phenotype in all four cases. While one patient was successfully transfused with blood from his sibling with the identical mutation, another case, a baby affected by haemolytic disease of the newborn, recovered without transfusion.
  
  
  CONCLUSIONS
  Despite the difficulties in undertaking a population study to determine the prevalence of this AQP1 c.601delG allele in the ethnic minority of Romani, the observations described in this report clearly suggest an accumulation of this mutation, which causes the Co(a-b-) phenotype, in Romani (Gypsy) patients. Further studies are necessary to prove such an accumulation.
authors: German Red Cross Blood Service West, Hagen and Bad Kreuznach, Germany.
authors: Brigitte K
authors: BK
authors: Flesch
authors: German Red Cross Blood Service West, Hagen and Bad Kreuznach, Germany.
authors: Burkhard
authors: B
authors: Just
authors: German Red Cross Blood Service West, Hagen and Bad Kreuznach, Germany.
authors: Robert
authors: R
authors: Deitenbeck
authors: German Red Cross Blood Service West, Hagen and Bad Kreuznach, Germany.
authors: Angelika
authors: A
authors: Reil
authors: German Red Cross Blood Service West, Hagen and Bad Kreuznach, Germany.
authors: Jürgen
authors: J
authors: Bux
authors: Tissue and Blood Bank, Immunohaematology Laboratory, Barcelona, Spain.
authors: Núria
authors: N
authors: Nogués
authors: Tissue and Blood Bank, Immunohaematology Laboratory, Barcelona, Spain.
authors: Eduardo
authors: E
authors: Muñiz-Diaz
mesh_terms: D000328:Adult; D051398:Aquaporin 1 / Q000235:genetics*; D001483:Base Sequence; D001789:Blood Group Antigens / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D006178:Romani People / Q000235:genetics*; D017384:Sequence Deletion
chemical_list: C496020:AQP1 protein, human; D001789:Blood Group Antigens; D051398:Aquaporin 1