Duffy blood group phenotypes and genotypes in Chinese

Serological and Molecular Study of the Duffy Blood Group among Malarial Endemic Region Residents in Brazil

Background:

The atypical chemokine receptor 1 (ACKR1) gene encodes the Duffy blood group antigens in two allelic forms: FY*A (FY*01) and FY*B (FY*02), which define the Fy(a+b-), Fy(a-b+), and Fy(a+b+) phenotypes. FY*BES (FY*02N.01) is a single T to C substitution at nucleotide -67 that prevents the FY*B from being expressed in red blood cells (RBCs).

Methods:

We evaluated 250 residents from a Brazilian malarial endemic region (RsMR). All individuals were phenotyped for Fy^a and Fy^b antigens and genotyped for FY*A, FY*B, FY*B^SE , and FY*B^weak alleles.

Results:

Among the 250 individuals, 209 (83.6%) reported previous malaria infection, and 41 (16.4%) did not. The Fy(a+b+) phenotype was present in 97/250 (38.8%), while the Fy(a-b-) was present in 7/250 (2.8%). The FY*A/FY*B was found in 130/250 (52%) and the FY*A/FY*A in 45/250 (18%). The c.1-67>TC was present, in homozygosity, in 11/250 (4.4%). Among 34 individuals with the Fy(a+b-) and FYA*/FYB* mutations, 4/34 (11.8%) had homozygosity for the c.1-67T>C. One individual presented the Fy(a+b-), FY*A/FY*B, and c.1-67T>C in homozygosis, whereas the other presented the Fy(a+b-), FY*A/FY*A, and c.1-67T>C in heterozygosis.

Conclusions:

We reported a low prevalence of the Fy(a-b-) in persons who had previously been infected with Plasmodium vivax (67.5%). We observed that 102/141 (72.3%) individuals expressing the Fy^b antigen had a P. vivax infection, indicating the importance of the Fy^b antigen, silenced by a c.1-67T>C mutation in homozygosis, in preventing the P. vivax infection. We showed that the c.1-67T>C mutation in the FY*A did not silence the FY*A expression on RBCs.

High frequency of the Duffy-negative genotype and absence of Plasmodium vivax infections in Ghana

Background

Recent studies from different malaria-endemic regions including western Africa have now shown that Plasmodium vivax can infect red blood cells (RBCs) and cause clinical disease in Duffy-negative people, though the Duffy-negative phenotype was thought to confer complete refractoriness against blood invasion with P. vivax. The actual prevalence of P. vivax in local populations in Ghana is unknown and little information is available about the distribution of Duffy genotypes. The aim of this study was to assess the prevalence of P. vivax in both asymptomatic and symptomatic outpatients and the distribution of Duffy genotypes in Ghana.

Methods

DNA was extracted from dried blood spots (DBS) collected from 952 subjects (845 malaria patients and 107 asymptomatic persons) from nine locations in Ghana. Plasmodium species identification was carried out by nested polymerase chain reaction (PCR) amplification of the small-subunit (SSU) rRNA genes. For P. vivax detection, a second PCR of the central region of the Pvcsp gene was carried out. Duffy blood group genotyping was performed by allele-specific PCR to detect the presence of the FY^ES allele.

Results

No cases of P. vivax were detected in any of the samples by both PCR methods used. Majority of infections (542, 94.8%) in the malaria patient samples were due to P. falciparum with only 1 infection (0.0017%) due to Plasmodium malariae, and 2 infections (0.0034%) due to Plasmodium ovale. No case of mixed infection was identified. Of the samples tested for the FY^ES allele from all the sites, 90.5% (862/952) had the FY^ES allele. All positive samples were genotyped as FY*B-33/FY*B-33 (Duffy-negative homozygous) and therefore classified as Fy(a−b−).

Conclusions

No cases of P. vivax were detected by both PCRs and majority of the subjects tested carried the FY^ES allele. The lack of P. vivax infections observed can be attributed to the high frequency of the FY^ES allele that silences erythroid expression of the Duffy. These results provide insights on the host susceptibility for P. vivax infections that had not been investigated in Ghana before.

Correlation between Duffy blood group phenotype and breast cancer incidence

Background

Different ethnicities have different distribution of Duffy blood group (DBG) phenotypes and different breast cancer morbidity. A study in our lab demonstrated that Duffy antigen/receptor for chemokines (DARC, also known as DBGP, the Duffy protein phenotype), led to the inhibition of tumorigenesis. Therefore, we tested the hypothesis that DBGP is correlated with breast cancer occurrence.

Methods

DBGP proteins were examined by indirect antiglobulin testing with anti-FYa and anti-FYb antibodies. The phenotypes were classified into four groups according to the agglutination reactions: FYa + FYb+, FYa + FYb-, FYa-FYb + and FYa-FYb-. The phenotypes and pathological diagnosis of consecutively hospitalized female patients (n = 5,022) suffering from breast cancer at the Shanghai Cancer Hospital and Henan Province Cancer Hospital were investigated. The relationships between DBGP expression with breast cancer occurrence, axillary lymph status, histological subtype, tumor size pathological grade and overall survival were analyzed.

Results

The incidence of breast cancer was significantly different between FYa + FYb + (29.8%), FYa + FYb- (33.2%), FYa-FYb + (45.6%) and FYa-FYb- (59.1%; P = 0.001). Significant different numbers of breast cancer patients had metastases to the axillary lymph nodes in the FYa + FYb + group (25.1%), FYa + FYb- (36.9%), FYa-FYb + (41.0%) and FYa-FYb- (50.0%, (P = 0.005). There was a statistical significance (p = 0.022) of the overall survival difference between patients with difference phenotypes. No significant difference was observed in cancer size (t-test, p > 0.05), histological cancer type (Fisher's exact test, p > 0.05) or histological grade (Fisher's exact test, p > 0.05) between every each DBGP group.

Conclusions

DBGP is correlated with breast cancer incidence and axillary lymph node metastasis and overall survival. Further investigations are required to determine the underlying mechanism of Duffy blood group phenotype on breast cancer risk.

Duffy blood group system genotyping in an urban Tunisian population

BACKGROUND

The Duffy blood group system, besides its relevance in transfusion medicine, is of major interest for population genetics. In fact, the Duffy molecule is the only red cell receptor for Plasmodium vivax, thus the fixation of FY*silent allele in western south-Saharan Africa resulted in the absence of this type of malaria in that area (for a review see Kwiatowski, Am J Hum Genet 77:171-192, 2005). For the Duffy functional role see, for example, Daniels (Vox Sanguinis 93:331-340, 2007).

METHODS

Duffy blood group distribution in 115 unrelated Tunisians was determined using the polymerase chain reaction with sequence specific primer (PCR-SSP) method detecting the five allelic versions of the FY gene. The red cell antigenic FY phenotype, for each donor, was deduced through DNA analysis. The blood samples of the positive FY*X alleles were investigated by serological methods, mainly the fixation-elution technique.

RESULTS

The following allele frequencies were found (after having excluded FY*X, which had frequency of 0.0174): FY*1 = 0.291 (expressed 0.260; silent 0.031); FY*2 = 0.709 (expressed 0.427; silent 0.282). The most surprising result in this work is the detection of the FY*1 silent allele, usually quite rare, in four samples (1.74%). For FY*2 silent, the predominant allele in Africans, genotyping results showed a prevalence of 29.57%. The FY locus was in Hardy-Weinberg equilibrium in the present sample.

CONCLUSION

When compared with European and African data, Tunisian samples demonstrated the presence of the common signs of these two ancestries (FY*2 and FY*X for the first population; and FY*2 silent for the last one). These data confirm the mixed roots of this urban Tunisian population already suggested by numerous studies on other haematological markers.