We report a rare case of GE:-13 and GE:-14 phenotype blood donor identified by random screening during blood bank routine.

This is a descriptive work using immunohematology data from immunohematology reference laboratory (LRI) where samples were tested.

A 29 year old blood donor, woman, self-declared as african american from the São Paulo city with no history of previous transfusions or pregnancies. Her blood was typed as O RhD+ (C-E+c+e+) and K- and the antibody screening was negative in gel cards. The phenotypes identified as Ge:-2,3 were confirmed by screening for GE:-2 blood group performed by hemagglutination in DG Gel cards using in house anti-Ge2 and others anti-Ge2 and anti-Ge3 from our inventory. Genomic DNA was isolated from donor whole blood and GE genotyping was performed by PCR-SSP techniques for analysis of exons 2, 3 and exon 4. The genetic variations that influence the expression of high-incidence antigens are deletions that involve exons 2, 3, 4 and the single nucleotide exchange (SNVs) in exons regions of the GYPC gene. These mutations, if not studied by molecular tests, may result in serological interpretation errors. Thus, sequencing by Sanger method of GE gene was performed and revealed a nucleotídeo change 59C>T (Pro20Leu in GPC) in Exon 2 in heterozygous and a nucleotide change 333A>C (non-coding) (Gly19Arg in GPD) in Exon 4 in homozigous state. No other nucleotide changes were identified.

One of the criteria for AABB reference laboratory certification in immunohematology is the screening for blood donors with rare phenotypes. For this reason, donors from the Hospital Israelita Albert Einstein are tested with anti-Ge2 antiserum. The aim is detect the rare phenotype Ge:-2, for compatibility tests in patients with anti-Ge2 alloantibody. The antigens of the Gerbich System are located on glycophorins C (GPC), D (GPD) or both. There are eight highly prevalent antigens known as Ge2, Ge3, Ge4, GEPL, GEAT, GETI, GECT, GEAR. Polymorphisms that involve high incidence antigens such as deletions in introns and single nucleotide exchange (SNVs) in exons regions of the GYPC gene, if not studied by molecular tests, may result in serological interpretation errors.

The fact of donor has a GECT allele (GE*01.-13) in heterozygosity does not imply the development of antibodies. The homozygous GEAR allele (GE*01-14) could result in the production of a rare anti-GEAR antibody in case of transfusion or pregnancy, however the clinical importance of this antibody is still unknown. Few articles report that these mutations can lead to loss of epitopes and the phenotypes can be interpreted as Ge:-2 or Ge:-3 in serological screening. This case showed that the molecular sequencing was crucial to determine the correct mutations present in the GYPC gene and consequently the correct deduction of the phenotype.