Frequencies of polymorphisms of the Rh, Kell, Kidd, Duffy and Diego systems of Santa Catarina, Southern Brazil

Frequencies of genetic variants of the Rh, Kell, Duffy, Kidd, MNS and Diego systems of northwest Rio Grande do Sul, Brazil

INTRODUCTION

To date, 340 antigen-organized 43 blood group systems are recognized, being ABO, Rh, Kell, Duffy, Kidd, MNS and Diego the most clinically relevant. The aim of this study was to assess the distribution of alleles and genotypes of the blood group systems Rh, Kell, Duffy, Kidd, MNS and Diego in 810 blood donors registered in the hemotherapy unit in northwest Rio Grande do Sul, Brazil METHODS: We evaluated the genetic variability of blood groups Rh (c.676G>C and c.307C>T), Kell (c.578C>T), Kidd (c.838A>G), Duffy (c.125A>G and c.1-67T>C), Diego (c.2561C>T) and MNS (c.143T>C) in 810 volunteer blood donors of Rio Grande do Sul, southern Brazil. The genetic profiling was performed through allelic discrimination assays using hydrolysis probes (TaqMan®) real-time PCR system.

RESULTS

The most frequent blood group genotypes found in our study population were: RHC*Cc (51.5%), RHC*ee (70.1%), FY*A/FY*B (49.3%), GATA -67T/T (93.5%), KEL*2/KEL*2 (93.4%), JK*A/JK*B (53.2%) and DI*02/DI*02 (95.4%). Some statistical differences were observed on comparing the population of this study with populations from other states in Brazil, mainly with population of Minas Gerais, Bahia and Paraná, which showed some differences from the population of Porto Alegre, which was more similar to those of Santa Catarina and São Paulo CONCLUSION: The frequency of red blood cell polymorphisms in our study is different from that of blood donors in other regions of Brazil. The results showed the importance of extended genotyping in adequate blood screening and the existence of rare genotypes in Brazilian regular blood donors.

Blood groups in Native Americans: a look beyond ABO and Rh

The study presents comparisons between blood group frequencies beyond ABO and Rh blood systems in Native American populations and previously published data from Brazilian blood donors. The frequencies of Diego (c.2561C>T, rs2285644), Kell (c.578C>T, rs8176058), Duffy (c.125A>G, rs12075, c.1-67T>C, rs2814778) and Kidd (c.838A>G, rs1058396) variants in Kaingang (n=72) and Guarani (n=234) populations from Brazil (1990-2000) were obtained and compared with data from these populations sampled during the 1960s and with individuals of different Brazilian regions. Data showed high frequencies of DI*01 and FY*01 alleles: 11.8% and 57.6% in Kaingang and 6.8% and 75.7% in Guarani groups, respectively. The main results indicated: (1) reduction in genetic distance over time of Kaingang and Guarani in relation to other Brazilian populations is suggestive of ongoing admixture; (2) significant differences in some frequencies of blood group markers (especially Diego, Kidd and Duffy) in relation to Native Americans and individuals from different geographical regions of Brazil. Our study shows that the frequency of red blood cell polymorphisms in two Native American groups is very different from that of blood donors, when we evaluated blood groups different from ABO and Rh systems, suggesting that a better ethnic characterization of blood unit receptors is necessary.

Lack of RH2 gene expression may have influenced the HIV pandemic in sub-Saharan Africa

OBJECTIVE

To evaluate the association between the Rhesus system RH2-blood group expression and susceptibility to HIV infection, viral load, CD4+ cell count and rate of CD4+ decline. We also aimed to determine if a country's HIV prevalence may be predicted from its RH2 relative frequency.

DESIGN

Our previous studies did not find any HIV-infected RH2 homozygotes. Therefore, the current cross-sectional study analysed a larger sample to determine whether HIV-infection also occurs in homozygotes. We also conducted a cross-sectional analysis of RH2 expression in an HIV natural history cohort in Botswana. Lastly, we analysed published data from 60 countries around the world to interrogate the link between RH2 frequency and HIV prevalence.

METHODS

One thousand and six hundred anticoagulated blood samples (800 HIV-positive and 800 HIV-negative) were phenotyped for RH2 using serological methods. The proportion of RH2-positive samples was compared across categories of HIV status and odds ratios calculated. Mean viral load and CD4+ cell counts from a natural history cohort study were also compared across categories of RH2. Kaplan--Meier plots were generated for 4-year CD4+-decline to 350 cells/μl.

RESULTS

No RH2 homozygotes were found among HIV-positives. Moreover, RH2-negatives were 1.37 times more likely to be HIV-positive than heterozygotes (P = 0.02) and 33 times more likely than RH2 homozygotes (P = 0.01). RH2-positive patients showed significantly higher mean CD4+ cell counts (P < 0.0001), lower viral load (P = 0.024) and slower CD4+ decline (P = 0.038).

CONCLUSION

RH2 is potentially a critical host genetic factor determining susceptibility of any population to HIV infection, and probably transcends most other factors in importance for HIV risk of infection.

Genetic variability of blood groups in southern Brazil

We evaluated genetic variability among the blood groups Kell (c.578C > T and c.1790T > C), Kidd (c.838A > G), Duffy (c.125A > G, c.265C > T and c.1-67T > C), Diego (c.2561C > T), MNS (c.143T > C) and Rh (c.676G > C) in Rio Grande do Sul in southern Brazil. Genetic profiling from 382 volunteer blood donors was performed through allelic discrimination assays using a hydrolysis probe (TaqMan®) with a real-time PCR system. The sample was divided into two groups: Euro-Brazilian and Afro-Brazilian. A comparison with studies from other regions of Brazil and the 1000 Genomes Database showed significant differences for almost all polymorphisms evaluated in our population. Population differentiation between the Euro- and Afro-Brazilian groups was low (F_ST value 0.055). However, when each locus was evaluated individually, KEL*06 and FY*02N.01 allele frequencies were significantly higher in the Afro-Brazilian group than in the Euro-Brazilian group. Ethnic classification that uses phenotypic criteria to find blood units with rare antigens may be important when there is a need to detect blood units with an absence of Duffy antigens. There is also a greater probability of finding donors in the Afro-Brazilian group. Taken together, the data indicate strong European and African contributions to the gene pool, with intense admixture.

The screening of rare blood donors in a highly admixed population: A new approach for Holley and Diego genotyping and impact of genomic and self-reported ancestry

OBJECTIVES

The present study aimed to develop strategies for genotyping DO*HY (Dombrock system) and DI*A/DI*B (Diego system) alleles and to evaluate the impact of genomic and self-declared ancestry on rare donor screening in admixed populations.

BACKGROUND

The antigens Hy and Di^b demonstrate clinical importance. The lack of antisera for the serological evaluation of these antigens makes it necessary to develop molecular methods. In addition, considering that some rare red blood cell phenotypes present differences in frequency between ethnic groups, it is important to assess the applicability of self-declared ancestry in the search for rare donors in admixed populations.

METHODS

DO*HY and DI*A/DI*B genotyping based on real-time polymerase chain reaction (PCR) was standardised. A total of 457 blood donors clustered by self-defined skin colour/race categories were genotyped. Furthermore, individual genomic ancestry was used in the analyses.

RESULTS

The assays developed are reproducible and provide satisfactory results even at low concentrations of DNA, which make them useful in situations where the DNA is scarce, such as dried blood spots on filter paper, or when screening for pooled samples. No significant difference was observed in the frequencies of the DI*A, DI*B and DO*HY, comparing the self-declared White (branco) donors with those who are Black (preto) and Brown (pardo).

CONCLUSION

Real-time PCR, especially using pooled samples, is a promising strategy to screen rare blood donors. Although both self-reported race/colour and some blood group phenotypes are associated with ancestry, the results point to a greater complexity in the application of self-declared race/colour in the screening of rare donors in admixed populations.

The synonymous 903C>G mutation in the alpha 1,4-galactosyltransferase gene in a Chinese woman with habitual abortion: A case report

RATIONALE

Habitual abortion is caused by complex and diverse factors, such as genetic factors, immune factors, endocrine factors, viruses, bacterial infections, and so on. Allogeneic antibodies, generated due to blood-group incompatibilities between a female and her fetus, are sometimes important for habitual abortion.

PATIENT CONCERNS

A 26-year-old woman had undergone abortions 3 times in July 2015 (17 weeks pregnant), March 2017 (15 weeks of gestation) and February 2018 (16 weeks pregnant) before she came to the Reproductive Medicine Center of our hospital for prenatal examinations without pregnancy.

DIAGNOSES

Unexplained habitual abortion.

INTERVENTIONS

A series of serological tests and nucleotide sequence of 1,4-galactosyltransferase (A4GALT) gene were performed.

OUTCOMES

The patient was the rare p phenotype in P1P blood system and the patient's habitual abortion was caused by anti-PP1P antibody which was generated naturally in persons with p phenotype. There was a mutation (903C>G, CCC>CCG) in the 3rd exon of A4GALT gene, which is likely a significant contributor to p phenotype.

LESSONS

This is the first case of habitual abortion caused by p phenotype due to independent 903C>G homozygous mutation with no similar record reported before, which indicates that it is a new class of mutation that leads to p phenotype.

DI*A and DI*B Allele Frequencies Among Southern Thai Blood Donors

Diego (DI) blood group genotyping is clinically important in Asian populations. Data of Diego blood type among southern Thais is still unknown. This study aimed to report DI*A and DI*B allele frequencies in southern Thai blood donors and to estimate potential risk of Di^a incompatibility and alloimmunization in Thai populations. DNA samples obtained from 427 southern Thai blood donors were genotyped for DI*A and DI*B alleles by polymerase chain reaction with sequence-specific primer. DI*A and DI*B allele frequencies among southern Thais were 0.0047 and 0.9953. Their frequencies were similar to those among American Native, Italian, Filipino, Alaska Native/Aleut and Hawaiian/Pacific Islander populations; while, the frequencies significantly differed from central and northern Thai, Southeast Asian, Brazilian, Southern Brazilian, Brazilian Japanese descendants, Japanese, Han Chinese, Chinese, and Korean populations (P < 0.05). The Di^a incompatibility among southern Thais (0.93%) was lower than among central Thais (3.49%), corresponding to a significantly lower probability of Di^a alloimmunization (P < 0.05). This is the first report of DI*A and DI*B allele frequencies among southern Thais, which is beneficial for not only creating information for estimating risk of alloimmunization, but also providing antigen-negative red cell donors to prevent both alloimmunization and adverse transfusion reactions.

Frequency of red blood cell genotypes in multi-transfused patients and blood donors from Minas Gerais, Southeast Brazil

BACKGROUND AND OBJECTIVES

The frequency of red blood cell (RBC) antigens in Brazil varies due to differences in the ethnic groups in different regions; however, these studies have not been performed in Minas Gerais, where African admixture is more prevalent in comparison with other states. Due to these facts, this study aimed to determine the frequency of RBC genotypes on Rh, Kell, Duffy and Kidd systems in blood donors and multi-transfused patients from Minas Gerais, Southeast Brazil.

METHODS

Blood samples were collected from 170 donors and 117 patients with different diagnosis and at least three RBC transfusions. DNA was extracted from leukocytes and genotyped by PCR-SSP, Multiplex or RFLP to alleles of the referred systems. The results were compared by the Chi-Square test, with a significance level of 5%.

RESULTS

The most frequent genotypes were: RHD+, RHCE*ce/RHCE*ce, KEL*2/KEL*2, FY*B-67T/FY*B-67T and JK*A/JK*B. FY*B-67C/FY*B-67C, RHD*Ψ and JK*A/JK*A genotypes were more prevalent in sickle cell disease (SCD) patients than in donors. Many differences in RBC genotype frequencies were observed in comparison with studies from other states and countries.

CONCLUSION

The results reinforce the importance of determining RBC genotypes of blood donors and patients in different regions of Brazil and the world, improving the transfusion safety of individuals requiring chronic RBC transfusions, especially those with SCD, due to ethnic differences in relation to donors.

Duffy blood group system: New genotyping method and distribution in a Brazilian extra-Amazonian population

Duffy blood group system is of interest in several fields of science including transfusion medicine, immunology and malariology. Although some methods have been developed for Duffy polymorphism genotyping, not all of them have been sufficiently described and validated, and all present limitations. At the same time, the frequency of Duffy alleles and antigens in some densely populated regions of the world are still missing. In this study we present new tests for genotyping the major alleles of the Duffy blood system and describe Duffy alleles and antigens in blood donors and transfusion-dependent patients in Minas Gerais, Brazil. A simple and reproducible strategy was devised for Duffy genotyping based on real-time PCR that included SNPs rs12075 and rs2814778. No significant differences between the allele frequencies were observed comparing blood donors and patients. Among the blood donors, the phenotype Fy(a-b+) was the most common and the Fy(a-b-) phenotype, associated with populations of African descent, was remarkably less common among subjects who self-identified as black in comparison to other ethnoracial categories. However, the African ancestry estimated by molecular markers was significantly higher in individuals with the allele associated to the Duffy null phenotype. The genotyping method presented may be useful to study Duffy genotypes accurately in different contexts and populations. The results suggest a reduced risk of alloimmunization for Duffy antigens and increased susceptibility for malaria in Minas Gerais, considering the high frequency of Duffy-positive individuals.

Distribution of DI*A and DI*B Allele Frequencies and Comparisons among Central Thai and Other Populations

Alloantibodies to the Diego (DI) blood group system, anti-Dia and anti-Dib are clinically significant in causing hemolytic transfusion reactions (HTRs) and hemolytic disease of the fetus and newborn (HDFN), especially in Asian populations with Mongolian ancestry. This study aimed to report the frequency of the DI*A and DI*B alleles in a Central Thai population and to compare them with those of other populations previously published. Altogether, 1,011 blood samples from unrelated healthy blood donors at the National Blood Centre, Thai Red Cross Society, Bangkok were included. Only 391 samples were tested with anti-Dia by conventional tube technique. All samples were genotyped for DI*A and DI*B alleles using an in-house polymerase chain reaction with sequence-specific primer (PCR-SSP) technique. The DI phenotyping and genotyping results were in 100% concordance. The DI*A and DI*B allele frequencies among 1,011 Central Thais were 0.0183 (37/2,022) and 0.9817 (1,985/2,022), respectively. Allele frequencies were compared between Central Thai and other populations. Our data shows that DI*A and DI*B allele frequencies are similar to Southeast Asian, Brazilian, Southern Brazilian and American Native populations; whereas, these frequencies significantly differ from those reported in East Asian, Italian, Alaska Native/Aleut, Hawaiian/Pacific Islander and Filipino populations (P<0.05), corresponding to the results of a matrix of geometric genetic distances. This study confirms that the prevalence of DI*A and DI*B alleles among Central Thais is similar to Southeast Asians and different to others populations of the world. A PCR-based identification of DI genotyping should overcome some of the serological limitations in transfusion medicine and provides a complementary tool for further population-genetic studies.