RHCE*ceAG (254C>G, Ala85Gly) is prevalent in blacks, encodes a partial ce-phenotype, and is associated with discordant RHD zygosity.

BACKGROUND: RHCE*ceAG has the nucleotide change c.254C>G, which encodes p.Ala85Gly associated with altered expression of e antigen. We analyzed serologic and DNA-based testing data on samples with RHCE*ceAG to determine its effect on antigen expression, linkage with RHD, and its prevalence in African Americans. STUDY DESIGN AND METHODS: Serologic testing was performed by standard methods. Genomic DNA was used for polymerase chain reaction-restriction fragment length polymorphism, RH-specific exon sequencing, and RHD zygosity, and Rh-cDNA was sequenced. Samples from 32 individuals referred for serologic problems, 57 patients with sickle cell disease, and 44 donors positive for c.254C>G were investigated. Allele prevalence was determined in random African Americans. RESULTS: Red blood cells from samples homozygous RHCE*ceAG/ceAG or in trans to RHCE*cE reacted variably with anti-e reagents and 17 samples from the 32 referred patients had alloanti-e in their plasma. The majority of samples with RHCE*ceAG, when tested for RHD zygosity gave discordant results between PstI-RFLP and hybrid box assay. Rare samples with 254C>G had additional allelic changes: one with c.697G (p.233Glu), three with c.733G, 941C (p.245Val, 314Ala), and two with c.307T (p.103Ser) encoding robust C antigen expression in the absence of other C-specific nucleotides. A total of 101 samples with RHCE*ceAG were encountered in 1159 randomly selected African Americans. CONCLUSIONS: RHCE*ceAG (c.254G, p.85Gly) encodes a partial phenotype and the absence of the high-prevalence antigen RH59 (CEAG). The allele was present in one in 11 African Americans and is most often in cis to a RHD deletion associated with discordant RHD zygosity. To further determine clinical significance, detection of this allele should be part of routine RHCE genotyping in this population.

Genomic analyses of RH alleles to improve transfusion therapy in patients with sickle cell disease.

BACKGROUND: Red cell (RBC) blood group alloimmunization remains a major problem in transfusion medicine. Patients with sickle cell disease (SCD) are at particularly high risk for developing alloantibodies to RBC antigens compared to other multiply transfused patient populations. Hemagglutination is the classical method used to test for blood group antigens, but depending on the typing methods and reagents used may result in discrepancies that preclude interpretation based on serologic reactivity alone. Molecular methods, including customized DNA microarrays, are increasingly used to complement serologic methods in predicting blood type. The purpose of this study was to determine the diversity and frequency of RH alleles in African Americans and to assess the performance of a DNA microarray for RH allele determination. MATERIAL AND METHODS: Two sets of samples were tested: (i) individuals with known variant Rh types and (ii) randomly selected African American donors and patients with SCD. Standard hemagglutination tests were used to establish the Rh phenotype, and cDNA- and gDNA-based analyses (sequencing, PCR-RFLP, and customized RHD and RHCE microarrays were used to predict the genotype). RESULTS: In a total of 829 samples (1658 alleles), 72 different alleles (40 RHD and 32 RHCE) were identified, 22 of which are novel. DNA microarrays detected all nucleotides probed, allowing for characterization of over 900 alleles. CONCLUSIONS: High-throughput DNA testing platforms provide a means to test a relatively large number of donors and potentially prevent immunization by changing the way antigen-negative blood is provided to patients. Because of the high RH allelic diversity found in the African American population, determination of an accurate Rh phenotype often requires DNA testing, in conjunction with serologic testing. Allele-specific microarrays offer a means to perform high-throughput donor Rh typing and serve as a valuable adjunct to serologic methods to predict Rh type. Because DNA microarrays test for only a fixed panel of allelic polymorphisms and cannot determine haplotype phase, alternative methods such as Next Generation Sequencing hold the greatest potential to accurately characterize blood group phenotypes and ameliorate the clinical course of multiply-transfused patients with sickle cell disease.

Alleles of the LAN blood group system: molecular and serologic investigations.

BACKGROUND: Anti-Lan has been implicated in hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. The LAN blood group system is encoded by ABCB6, whose gene product, ABCB6, belongs to the ATP-binding cassette (ABC) efflux transporter superfamily. The purpose of this study was to characterize additional alleles by analyzing DNA from 14 (13 unrelated) subjects whose red blood cells were serologically defined as Lan-, Lan+(w) /-, or Lan+(w) . STUDY DESIGN AND METHODS: Genomic DNA was extracted from blood samples recovered from liquid nitrogen storage. Intronic primers flanking each of the ABCB6 coding exons were used for polymerase chain reaction amplification. Amplicons were sequenced and analyzed by standard methods. RESULTS: Among the study subjects, we identified five alleles (one with a nonsense change, three with frameshifts, one with a missense change) that encode the Lan- phenotype and four alleles (with missense changes) encoding either Lan+(w) or Lan+(w) /- phenotypes. CONCLUSIONS: Of the nine alleles we identified, three were novel and six were previously documented in the dbSNP. Of these six, only one allele was previously associated with Lan negativity. To date, 19 ABCB6 alleles that encode Lan- or Lan+(w) /-, or Lan+(w) phenotypes have been described.

A review of the JR blood group system.

The JR blood group system (ISBT 032) consists of one antigen,Jra, which is of high prevalence in all populations. The rare Jr(a-) phenotype has been found mostly in Japanese and other Asian populations, but also in people of northern European ancestry, in Bedouin Arabs, and in one Mexican. Anti-Jra has caused transfusion reactions and is involved in hemolytic disease of the fetus and newborn. The Jra antigen is located on ABCG2 transporter, a multipass membrane glycoprotein (also known as the breast cancer resistance protein, BCRP), which is encoded by the ABCG2 gene on chromosome 4q22.1. The Jr(a-) phenotype mostly results from recessive inheritance of ABCG2 null alleles caused by frameshift or nonsense changes.

SC*994C>T causes the Sc(null) phenotype in Pacific Islanders and successful transfusion of Sc3+ blood to a patient with anti-Sc3.

Antigens in the SC blood group system are expressed by the human erythrocyte membrane-associated protein (ERMAP).Two molecular bases have been reported for the Sc,un phenotype:SC*307del2 and SC*994C>T. We report our investigation of the molecular background of five Sc,n1 individuals from the Pacific Islands and describe the successful transfusion of Sc3+ blood to a patient with anti-Sc3 in her plasma. SC (ERMAP) exons 2,3, and 12 and their flanking intronic regions were analyzed. TheSC*994C>T change introduces a restriction enzyme cleavage site for Tsp45I, and polymerase chain reaction (PCR) products from exon 12 were subjected to this PCR-restriction fragment length polymorphism (RFLP) assay. The five samples had the variant SC*994T/T. One sample, from a first cousin of one Marshallese proband, was heterozygous for SC*1514C/T (in the 3' untranslated region); the other four samples were SC*1514C/C(consensus sequence). Samples from white donors (n = 100) and African American donors (n = 99) were tested using the Tsp45IPCR-RFLP assay; all gave a banding pattern that was consistent with the SC*994C/C consensus sequence. In all five samples,our analyses showed homozygosity for the nonsense nucleotide change SC*994C>Tin an allele carrying the nucleotide associated with SLd. Further investigation determined that one of the probands reported previously with the SC*994C>T change was from the Marshall Islands (which form part of the Micronesian Pacific Islands) and the other was from an unspecified location within the large collection of Pacific Islands. Taken together, the five known probands with the SC*994C>T silencing nucleotide change were from the Pacific Islands.

RHCE*ceMO is frequently in cis to RHD*DAU0 and encodes a hr(S) -, hr(B) -, RH:-61 phenotype in black persons: clinical significance.

BACKGROUND: RHCE*ceMO has nucleotide changes 48G>C and 667G>T, which encode, respectively, 16Cys and 223Phe associated with altered expression of e antigen. RHD*DAU0 has Nucleotide 1136C>T, which encodes 379Met associated with normal levels of D. We compiled serologic and DNA testing data on samples with RHCE*ceMO to determine the red blood cell (RBC) antigen expression, antibody specificity, RHD association, and the prevalence in African-American persons. STUDY DESIGN AND METHODS: Serologic testing was performed by standard methods. Genomic DNA was used for polymerase chain reaction-restriction fragment length polymorphism and RH-exon sequencing, and for some, Rh-cDNA was sequenced. Seventy-seven (50 donor and 27 patient) samples with RHCE*ceMO were studied, and 350 African-American persons were screened for allele prevalence. RESULTS: RBCs from RHCE*ceMO homozygotes (or heterozygotes with RHCE*cE in trans) were weak or nonreactive with some anti-e and were nonreactive with polyclonal anti-hr(S) and anti-hr(B) . Twenty-three transfused patients homozygous for RHCE*ceMO/ceMO or with RHCE*ceMO in trans to RHCE*cE or *ce had alloanti-e, anti-f, anti-hr(S) /hr(B) , or an antibody to a high-prevalence Rh antigen. Three patients with alloanti-c had RHCE*ceMO in trans to RHCE*Ce. RHD*DAU0 was present in 30% of African-American persons tested and in 69 of 77 (90%) of samples with RHCE*ceMO. CONCLUSIONS: RHCE*ceMO encodes partial e, as previously reported, and also encodes partial c, a hr(S) - and hr(B) - phenotype, and the absence of a high-prevalence antigen (RH61). The antibody in transfused patients depended on the RHCE allele in trans. RHCE*ceMO was present in one in 50 African-American persons with an allele frequency of 0.01, is often linked to RHD*DAU0, and is potentially of clinical significance for transfusion.

Molecular basis of two novel and related high-prevalence antigens in the Kell blood group system, KUCI and KANT, and their serologic and spatial association with K11 and KETI.

BACKGROUND: The numerous antigens in the Kell blood group system result from missense nucleotide changes in KEL. Antibodies to antigens in this system can be clinically important. We describe six probands whose plasma contained antibodies to high-prevalence Kell antigens and discuss their relationship. STUDY DESIGN AND METHODS: Polymerase chain reaction amplification, direct sequencing, restriction fragment length polymorphism assays, hemagglutination, flow cytometry, and protein modeling were performed by standard methods. RESULTS: Proband 1 (KUCI) and her serologically compatible sister were heterozygous for a nucleotide change in Exon 11 (KEL*1271C/T; Ala424Val). Proband 2 (KANT) was heterozygous for KEL*1283G/T (Arg428Leu) and KEL*1216C/T (Arg406Stop) in Exon 11. Red blood cells (RBCs) from Proband 1 and her sister were not agglutinated by plasma from Proband 2; however, RBCs from Proband 2 were agglutinated by plasma from Proband 1. Probands 3, 4, 5, and 6 had the KEL*1391C>T change associated with the previously reported KETI- phenotype. Proband 5 was also homozygous for KEL*905T>C encoding the K11-K17+ phenotype. Hemagglutination studies revealed an association between KUCI, KANT, KETI, and K11. Protein modeling indicated that whereas Ala424 and Arg428 are clustered, Val302 and Thr464 are not. CONCLUSION: Ala424 in the Kell glycoprotein is associated with the high-prevalence Kell antigen, KUCI (ISBT 006032), which is detected by the antibody of Proband 1. Arg428 is associated with the high-prevalence Kell antigen, KANT (ISBT 006033). The association between KUCI, KANT, KETI, and K11 and the results of protein modeling are discussed.

Three novel alleles in the Kell blood group system resulting in the Knull phenotype and the first in a Native American.

BACKGROUND: Antibodies to Kell antigens can be clinically important but only limited data are published regarding anti-Ku. Missense nucleotide changes in KEL account for the numerous Kell antigens, the K(mod) phenotype, and even the K(null) phenotype. STUDY DESIGN AND METHODS: DNA and RNA were extracted from white blood cells and polymerase chain reaction-based assays, cloning, and sequencing were done using standard protocols. RESULTS: The anti-Ku in Proband 1, which caused hemolytic disease and anemia of the fetus and newborn, was a mixture of immunoglobulin (Ig)G1 and IgG2 and gave macrophage indexes ranging from 47.8 to 59.3 (>20 is clinically significant) in a monocyte monolayer assay. The proband, her daughter, and compatible sister had a heterozygous deletion of a G in Exon 18 (Nucleotide c.1972_1975delG) in a KEL*02 allele causing a frameshift. The mechanism for silencing of the other KE*02 allele was undetermined. Proband 2 was heterozygous for a nonsense change (KEL*382C/T; Arg128Stop), a missense change (KEL*244T/C; Cys82Arg), and KEL*578T/C (KEL*01/KEL*02). Direct sequencing of cDNA and cloning showed that the KEL*01 allele had 244C, 382C, 578T and the KEL*02 allele carried 244T, 382T, 578C. CONCLUSIONS: We report a novel single-nucleotide deletion, a novel nonsense allele, and a novel missense allele all resulting in the K(null) phenotype. The anti-Ku from Proband 1 was clinically important.

Emily Cooley lecture 2012: Emily Cooley and techniques that have been applied to characterize DO and JR blood groups.

Emily Cooley was a well-respected medical technologist and morphologist with a remarkable skill set. She was highly regarded both professionally and personally. The "Emily Cooley Lectureship and Award" was established to honor her in particular and medical technologists in general. This article first reviews the history of the Emily Cooley award and provides some of the reasons why it carries her name. Then, using two blood group systems, DO and JR, it illustrates how many discoveries regarding blood groups were dependent on access to techniques.

The JR blood group system: identification of alleles that alter expression.

BACKGROUND: The ABCG2 gene encodes antigens of the JR blood group system. Red blood cells (RBCs) from individuals homozygous for ABCG2 null alleles are nonreactive with polyclonal and monoclonal anti-Jr(a) . However, some RBCs have been defined as Jr(a+(W) /-) or Jr(a-), particularly when tested with polyclonal anti-Jr(a) . In an effort to resolve these apparent serologic ambiguities, the current study was undertaken. STUDY DESIGN AND METHODS: Hemagglutination of RBCs from two individuals known to express a single copy of functional ABCG2 were compared to RBCs from eight unrelated, previously characterized, Jr(a+(W) /-) donors. Standard polymerase chain reaction-based methods were used to characterize ABCG2 alleles. RESULTS: Two monoclonal anti-Jr(a) clones agglutinated RBCs from the eight Jr(a+(W) /-) study subjects. Two of these subjects were homozygous for a missense ABCG2 change (c.1858A; Asp620Asn). Two were heterozygous for two missense changes; one was c.1858G>A and c.421C>A (Asp620Asn; Gln141Lys), and the other was c.1714A>C and c.421C>A (Ser572Arg; Gln141Lys). The remaining four subjects were heterozygous for c.421C>A (Gln141Lys), and for one of four null alleles. CONCLUSIONS: We have identified three ABCG2 alleles that are newly associated with weakened Jr(a) expression. One of these is novel, the missense allele c.1714A>C (Ser572Arg) and two that have been previously described c.421C>A (rs2231142; Gln141Lys) and c.1858G>A (rs34783571; Asp620Asn). In addition, we found a novel, presumed null allele, c.1017_1019delCTC (Ser340del).

Isolation and functional characterization of human erythroblasts at distinct stages: implications for understanding of normal and disordered erythropoiesis in vivo.

Terminal erythroid differentiation starts from morphologically recognizable proerythroblasts that proliferate and differentiate to generate red cells. Although this process has been extensively studied in mice, its characterization in humans is limited. By examining the dynamic changes of expression of membrane proteins during in vitro human terminal erythroid differentiation, we identified band 3 and α4 integrin as optimal surface markers for isolating 5 morphologically distinct populations at successive developmental stages. Functional analysis revealed that these purified cell populations have distinct mitotic capacity. Use of band 3 and α4 integrin enabled us to isolate erythroblasts at specific developmental stages from primary human bone marrow. The ratio of erythroblasts at successive stages followed the predicted 1:2:4:8:16 pattern. In contrast, bone marrows from myelodysplastic syndrome patients exhibited altered terminal erythroid differentiation profiles. Thus, our findings not only provide new insights into the genesis of the red cell membrane during human terminal erythroid differentiation but also offer a means of isolating and quantifying each developmental stage during terminal erythropoiesis in vivo. Our findings should facilitate a comprehensive cellular and molecular characterization of each specific developmental stage of human erythroblasts and should provide a powerful means of identifying stage-specific defects in diseases associated with pathological erythropoiesis.

The JR blood group system (ISBT 032): molecular characterization of three new null alleles.

BACKGROUND: Jr(a) (ISBT 901005) is a high-prevalence antigen unassigned to a blood group system. People lacking this antigen have been found in all populations studied but most commonly in Asians. Two recent reports established that ABCG2-null alleles encode the Jr(a-) phenotype and these studies provided the impetus to study other Jr(a-) individuals. STUDY DESIGN AND METHODS: Blood samples were part of our rare donor-patient collection. DNA was isolated and analyzed by standard techniques. RESULTS: In samples from 13 Jr(a-) study subjects, we found six alleles with nonsense nucleotide changes, three (c.784T, c.1591T, and c.337T) were novel. Twelve of the samples were homozygous for nonsense single-nucleotide polymorphisms (SNPs): eight were c.376T, two were c.706T, one was c.784T, and one was c.1591T. Each of these alleles predicts a truncated ABCG2 product, Gln126Stop, Arg236Stop, Gly262Stop, and Gln531Stop, respectively. One study subject was heterozygous for two nonsense SNPs: c.337C/T (Arg113Stop) and c.736C/T (Arg246Stop). CONCLUSIONS: Jr(a) is the sole antigen in the newly established JR blood group system (ISBT 032001). The previous ISBT designation (901005) is now obsolete. Since ABCG2null alleles define the Jr(a-) phenotype, an explanation for why no antithetical low-prevalence antigen to Jr(a) has been found, and also why anti-Jr(a) made by people with any of these JRnull alleles are mutually compatible has been determined. Based on our findings DNA-based genotyping can be developed to replace the serologic methods that are currently used to identify Jr(a-) blood donors.

RHCE*ceTI encodes partial c and partial e and is often in cis to RHD*DIVa.

BACKGROUND: In the Rh blood group system, variant RhD and RhCE express several partial antigens. We investigated RH in samples with partial DIVa that demonstrated weak and variable reactivity with anti-C. STUDY DESIGN AND METHODS: Standard hemagglutination techniques, polymerase chain reaction-based assays, and RH sequencing were used. RESULTS: DNA analysis showed that six red blood cell (RBC) samples with weak and inconsistent reactivity with anti-C lacked RHCE*C, but all had RHD*DIVa, which encodes partial D and Go(a) . We then tested RBCs from 19 Go(a+) cryopreserved samples (confirmed to have RHD*DIVa) with four anti-C and observed weak variable reactions. RHCE genotyping found all but one of the samples with RHD*DIVa also had RHCE nt 48G>C and 1025C>T, named RHCE*ceTI. Lookback of samples referred for workup and found to have either allele revealed 47 of 55 had both RHD*DIVa and RHCE*ceTI, four had RHD*DIVa without RHCE*ceTI, and four had RHCE*ceTI without RHD*DIVa. Alloanti-c was found in a patient with c+ RBCs and RHCE*ceTI in trans to RHCE*Ce, and alloanti-e was found in a patient with e+ RBC and RHCE*ceTI in trans to RHCE*cE. RHD*DIVa in trans to RHD erroneously tested as RHD hemizygous. CONCLUSIONS: RHD*DIVa and RHCE*ceTI almost always, but not invariably, travel together. This haplotype is found in people of African ancestry and the RBCs can demonstrate aberrant reactivity with anti-C. RHCE*ceTI encodes partial c and e antigens. We confirm that RHD zygosity assays are unreliable in samples with RHD*DIVa.

The low-prevalence Rh antigen STEM (RH49) is encoded by two different RHCE*ce818T alleles that are often in cis to RHD*DOL.

BACKGROUND: STEM (RH49) is a low-prevalence antigen in the Rh blood group system. A scarcity of anti-STEM has precluded extensive study of this antigen. We report that two alleles with a RHCE*ce818C>T change encode a partial e, and a hr(S) -, hr(B) +, STEM+ phenotype and that both alleles are frequently in cis to RHD*DOL1 or RHD*DOL2. STUDY DESIGN AND METHODS: Blood samples were from donors and patients in our collections. Hemagglutination, DNA, and RNA testing was performed by standard techniques. RESULTS: Fourteen STEM+ samples were heterozygous RHCE*ce818C/T: six had RHCE*ceBI and eight had a novel allele, RHCE*ceSM. Eleven were heterozygous for RHD*DOL1 or RHD*DOL2. Eleven samples, previously typed STEM-, had RHCE*ce818C/C (consensus nucleotide). RBCs from informative STEM+ samples were e+/- hr(S) - hr(B) +. One person who was heterozygous RHCE*ceBI and RHCE*cE had an anti-e-like antibody in her plasma, and one person, who was hemizygous for RHD*DOL2, had anti-D in her plasma. CONCLUSIONS: We show that two alleles with a RHCE*ce818C>T change (RHCE*ceBI and RHCE*ceSM) encode a hr(S) - hr(B) + STEM+ phenotype. In addition, both alleles are frequently in cis to RHD*DOL1 or RHD*DOL2 and RHCE*ceBI encodes a partial e antigen. In the small cohort of samples tested, RHD*DOL invariably traveled with RHCE*ce818T. Our study also confirmed the presumption that RHD*DOL2, like RHD*DOL1, encodes a partial D antigen and the low-prevalence antigen DAK.

ABCG2 null alleles define the Jr(a-) blood group phenotype.

The high-incidence erythrocyte blood group antigen Jr(a) has been known in transfusion medicine for over 40 years. To identify the gene encoding Jr(a), we performed SNP analysis of genomic DNA from six Jr(a-) individuals. All individuals shared a homozygous region of 397,000 bp at chromosome 4q22.1 that contained the gene ABCG2, and DNA sequence analysis showed that ABCG2 null alleles define the Jr(a-) phenotype.

DIII Type 7 is likely the original serologically defined DIIIb.

BACKGROUND: Due to their homology, close proximity, and opposite orientation, RHD and RHCE can exchange nucleotides giving rise to variant alleles. Some of these variants encode the so-called partial phenotypes. The DIII partial D category has been subdivided into DIIIa, DIIIb, DIIIc, DIII Type 4, DIII Type 6, and DIII Type 7. During DNA-based screening tests, we identified a second example of DIII Type 7 in a Dce donor from South Africa. Our study describes hemagglutination tests on this sample and raises a question regarding the molecular basis of the originally defined DIIIb category. STUDY DESIGN AND METHODS: Hemagglutination and DNA testing were performed by standard techniques. RESULTS: Red blood cells from this DIII Type 7 donor typed D+C-E-c+e+G-, DAK+ and did not react with anti-D made by people with the DIII phenotype. The allele is RHD*DIII 150C, 178C, 201A, 203A, 307C, 410T, 455C, 602G, 667G. CONCLUSIONS: Based on the serotype and ethnicity (black African), it is likely that DIII Type 7 is the originally defined DIIIb category.

A unique case of thyroid dysgenesis in a neonate.

Neonates with congenital hypothyroidism often demonstrate ectopic thyroid tissue. However, 2 sites of abnormally located thyroid tissue are exceptionally rare with only one other published case on a neonate. The authors present a unique case of a neonate who was found to have congenital hypothyroidism on laboratory screening; Tc-99m pertechnetate scintigraphy demonstrated 2 sites of abnormal uptake: one at the base of the tongue and the other in the midline at the expected location of the thyroid bed.

Nucleotide deletion in RHCE*cE (907delC) is responsible for a D- - haplotype in Hispanics.

BACKGROUND: Lack of Cc and Ee expression is associated with either hybrid alleles in which regions of RHCE are replaced by RHD or nucleotide deletion(s) in RHCE. The former have been found as D- - phenotypes, and the latter as Rh(null) when accompanied by deletion of RHD. We investigated RH in eight samples, three presenting as D- -, whose c-E- red blood cell (RBC) typing was discordant with the RHCE genotype that predicted c+E+. STUDY DESIGN AND METHODS: Serologic and molecular testing was performed by standard methods. CASES AND RESULTS: RBCs from Patient 1 were D+C-E-c+e+(w) but DNA testing predicted E+. RBCs from Patients 2, 3, and 4 typed as D+C-E-c-e- but DNA testing predicted c+E+. All had alloantibodies strongly reactive with all RBCs tested except D- - and Rh(null). Patient 5 had anti-c and anti-E but DNA testing predicted she was c+E+. RBCs from three donors typed D+C+E-c-e+ with DNA testing predicting c+E+. All had RHCE*cE with deletion of nucleotide 907C in Exon 6 predicted to cause a premature stop codon at Amino Acid 303 (Leu303Stop). HphI polymerase chain reaction-restriction fragment length polymorphism was used to confirm the deletion and to screen 100 Hispanic, 100 Caucasian, and 100 African American donor samples. One additional example was found. CONCLUSIONS: A novel allele, RHCE*cE 907delC (ISBT provisional designation RHCE*03N.02), silences c and E and in the homozygous state resulted in a D- - phenotype and production of anti-Rh17. All eight probands were Hispanic. The allele is associated with discrepant molecular typing, with an approximate frequency of 0.005 in Hispanics.

Population genetics of GYPB and association study between GYPB*S/s polymorphism and susceptibility to P. falciparum infection in the Brazilian Amazon.

BACKGROUND: Merozoites of Plasmodium falciparum invade through several pathways using different RBC receptors. Field isolates appear to use a greater variability of these receptors than laboratory isolates. Brazilian field isolates were shown to mostly utilize glycophorin A-independent invasion pathways via glycophorin B (GPB) and/or other receptors. The Brazilian population exhibits extensive polymorphism in blood group antigens, however, no studies have been done to relate the prevalence of the antigens that function as receptors for P. falciparum and the ability of the parasite to invade. Our study aimed to establish whether variation in the GYPB*S/s alleles influences susceptibility to infection with P. falciparum in the admixed population of Brazil. METHODS: Two groups of Brazilian Amazonians from Porto Velho were studied: P. falciparum infected individuals (cases); and uninfected individuals who were born and/or have lived in the same endemic region for over ten years, were exposed to infection but have not had malaria over the study period (controls). The GPB Ss phenotype and GYPB*S/s alleles were determined by standard methods. Sixty two Ancestry Informative Markers were genotyped on each individual to estimate admixture and control its potential effect on the association between frequency of GYPB*S and malaria infection. RESULTS: GYPB*S is associated with host susceptibility to infection with P. falciparum; GYPB*S/GYPB*S and GYPB*S/GYPB*s were significantly more prevalent in the in the P. falciparum infected individuals than in the controls (69.87% vs. 49.75%; P<0.02). Moreover, population genetics tests applied on the GYPB exon sequencing data suggest that natural selection shaped the observed pattern of nucleotide diversity. CONCLUSION: Epidemiological and evolutionary approaches suggest an important role for the GPB receptor in RBC invasion by P. falciparum in Brazilian Amazons. Moreover, an increased susceptibility to infection by this parasite is associated with the GPB S+ variant in this population.