Distribution of Diego blood group alleles and identification of four novel mutations on exon 19 of SLC4A1 gene in the Chinese Han population by polymerase chain reaction sequence-based typing

Genetic profile of RHCE, Kell, Duffy, Kidd, Diego and MNS hybrid glycophorins blood groups in ethnic northeastern Thais: Alleles, genotypes and risk of alloimmunisation

BACKGROUND

Antibodies against blood group antigens play a key role in the pathophysiology of haemolytic transfusion reactions (HTRs) and haemolytic disease of the fetus and newborn (HDFN). This study aimed to determine the frequencies of alleles, genotypes, and risk of alloimmunisation of clinically significant blood group systems in ethnic northeastern Thais.

METHODS

In total, 345 unrelated, healthy, ethnic northeastern Thais were tested using the in-house PCR-sequence specific primers (PCR-SSP) method for simultaneously genotyping of RHCE, Kell, Duffy, Kidd, Diego and MNS glycophorin hybrids and results confirmed by Sanger sequencing.

RESULTS

In this cohort, the alleles RHCE*C (81.0%) and RHCE*e (84.8%) were more prevalent than RHCE*c (19.0%) and RHCE*E (15.2%). The most common predicted haplotype combinations of the RHCE alleles were C+c-E-e+(R1R1) (59.4%) followed by the C+c+E+e+ (R1R2) (20.6%) and C+c+E-e+ (R1r) (11.3%). The KEL*01 allele was not found in this study. The frequencies of FY*01 and FY*02 were 88.3% and 11.7%, respectively. The genotype FY*02/02 was found in four samples (1.2%). The frequencies of JK*01 and JK*02 were 52.5% and 47.5%, respectively. Homozygous JK*02/02 was found in 81 samples (23.5%). The frequencies of DI*01 and DI*02 were 0.6% and 99.4%, respectively. In total, 64 samples (18.6%) were found to carry the MNS glycophorin hybrids.

CONCLUSIONS

Our results indicated a possible high risk of c, E, Fyb, Jka, Jkb and Mia alloimmunisation in these populations. Moreover, methods established for genotyping clinically significant blood groups in this study can now be utilised in routine clinical application.

Identification of a novel DI*02(2558T) allele associated with weakened expression of DI2 antigen

BACKGROUND

The distribution of DI1/DI2 antigens of the Diego blood group system is polymorphic in Mongoloid populations and the corresponding alloantibodies are clinically significant. Here a novel DI variant was found by donor screening, and the effect of the novel and previously reported mutations on expression of DI1/DI2 antigens and Band 3 protein was explored.

STUDY DESIGN AND METHODS

DNA samples of 1150 Chinese donors were collected. DI*01/DI*02 genotyping was determined by Sanger sequencing. For the carrier of novel allele, the expression of Band 3 and DI1/DI2 antigens on red blood cells (RBCs) was detected by Western blot and flow cytometry, respectively. in vitro expression studies were conducted by transfecting the mutant (including the novel and three reported DI*02(2534T), DI*02(2358_2359insCAC), and DI*02(2572T) alleles) or wild-type DI*02 constructs into HEK 293T cells, the expression of Band 3 and DI1/DI2 antigens was analyzed.

RESULTS

A novel heterozygous mutation (c.2558C>T, p.Thr853Met), which is located near the DI1/DI2 polymorphism site (c.2561T>C), was identified in a donor with DI:-1,2 phenotype. Reduced expression of DI2 antigen was observed on the RBCs, while weakened expression of Band 3 and absence of DI2 antigen were detected in cells transfected with the mutant DI*02(2558T) construct. In addition, absent or decreased expression of Band 3 and DI2 antigen was also detected in cells transfected with three reported mutant constructs.

CONCLUSION

The novel DI*02(2558T) allele and three previously described DI mutations can affect the expression of Band 3 protein and/or DI2 antigen and/or interfere with DI*01/DI*02 genotyping result.