Wide Variety of Point Mutations in the H Gene of Bombay and Para-Bombay Individuals That Inactivate H Enzyme

A Pedigree Investigation of H-antigen Deletion Caused by Mutation of 658 C to T in the FUT1 Gene

H-antigen deletion is often caused by FUT1 gene mutation, which is a very rare blood group. In this case, the H-antigen phenotype, FUT1, FUT2 sequences, and family genetic investigation of a 26-year-old patient (proband) and her three family members were studied. The results showed that the proband and little her brother were H-deficient phenotype, their ABO genotype of both was A/O1, her father was A/B, and her mother was O1/O1. The proband and her little brother's FUT1 phenotype were both h3|h3, with a homozygous mutation 658C > T in their FUT1 gene, and the FUT1 phenotype of their parents' were H|h3, with a heterozygous mutation (658C > T) in their FUT1 gene. The result of whole gene sequencing showed that the father of the proband had a deletion of CHR19.49,255,178-49,257,177 in the FUT1 gene (hg19 was used as the reference). The results of the family investigation showed that the mutation of site 658 in the FUT1 gene between offspring and parents was consistent with Mendelian inheritance law.

In vitro synthesis of mucin-type O-glycans using saccharide primers comprising GalNAc-Ser and GalNAc-Thr residues

Mucin-type O-glycosylation of serine or threonine residue in proteins is known to be one of the major post-translational modifications. In this study, two novel alkyl glycosides, N^α-lauryl-O-(2-acetamido-2-deoxy-α-d-galactopyranosyl)-l-serineamide (GalNAc-Ser-C12) and N^α-lauryl-O-(2-acetamido-2-deoxy-α-d-galactopyranosyl)-l-threonineamide (GalNAc-Thr-C12) were synthesized as saccharide primers to prime mucin-type O-glycan biosynthesis in cells. Upon incubating human gastric cancer MKN45 cells with the saccharide primers, 22 glycosylated products were obtained, and their structures were analyzed using liquid chromatography-mass spectrometry and enzyme digestion. The amounts of glycosylated products were dependent on the amino acid residues in the saccharide primers. For example, in vitro synthesis of T antigen (Galβ1-3GalNAc), fucosyl-T (Fucα1-2Galβ1-3GalNAc), and sialyl-T (NeuAcα2-3Galβ1-3GalNAc) preferred a serine residue, whereas sialyl-Tn (NeuAcα2-6GalNAc) preferred a threonine residue. Furthermore, the glycosylated products derived from GalNAc-Ser/Thr-C12 and Gal-GalNAc-Ser/Thr-C12 using cell-free synthesis showed the same amino acid selectivity as those in the cell experiments. These results indicate that glycosyltransferases involved in the biosynthesis of mucin-type O-glycans distinguish amino acid residues conjugated to GalNAc. The saccharide primers developed in this study might be useful for comparing mucin-type oligosaccharides in cells and constructing oligosaccharide libraries to study cell function.

A Para-Bombay Blood Group Case Associated with a Novel FUT1 Mutation c.361G>A

Background

Here we report a case of para-Bombay phenotype due to a novel mutation FUT1 c.361G>A p.(Ala121Thr) and a nonfunctional allele FUT1*01N.13(c.881_882delTT) which showed a discrepancy in the routine ABO blood group typing.

Materials and Methods

The ABO phenotype and the Lewis blood group were typed with serological methods. The ABH antigens in saliva were determined by a hemagglutination inhibition test. The CDS region of ABO, FUT1and FUT2 were amplified with polymerase chain reaction and then directly sequenced. The novel mutation was confirmed by cloning and sequencing. Three-dimensional (3-D) structural analysis of the mutant and wild-type Fut1 were performed by the Chimera software.

Results

A, B and H antigens were not detected on the surface of red blood cells (RBCs) by the serological technique, and the B and H blood group substances were detected in the saliva, while the Lewis phenotype was Le(a-b+). Sequencing and cloning analysis showed the presence of a novel FUT1 mutation c.361G>A and a nonfunctional allele FUT1*01N.13(c.881_882delTT). The ABO genotype was ABO*B.01/ABO*O.01.01. The in silico analysis showed that the mutation p.(Ala121Thr) of FUT1did not change the 3-D structure of the whole enzyme but caused a certain amplitude of turnover in the loop region where Ala121 was located.

Conclusions

A novel FUT1 allele (FUT1*c.361G>A) was identified in a Chinese individual with para-Bombay B phenotype. The FUT1c.361G>A mutation may significantly downregulate the expression of H antigens on RBCs by damaging the enzyme conformation.

Two novel FUT1 alleles that cause para-Bombay phenotype in a Chinese individual

BACKGROUND

Bombay and para-Bombay phenotypes, which arise from gene mutations of α-1,2-fucosyltransferase FUT1, are very rare in Chinese population. A para-Bombay phenotype Chinese individual with two novel FUT1 mutations was reported here.

STUDY DESIGN AND METHODS

The peripheral blood and saliva samples of the proband and her family members were collected after informed consent. ABO and H blood group phenotyping was performed by haemagglutination methods. ABO genotype was determined by PCR-SSP kit. A, B, and H antigens in saliva were detected by a hemagglutination inhibition test. Fragments encompassing the full coding region of FUT1 and FUT2 genes were PCR amplified and sequenced. Allelic sequences were validated by cloning and sequencing individual colonies.

RESULTS

The serologic reaction results of the proband revealed that A, B, and H antigen were absent on RBCs, but B and H antigen were presented in saliva, and the serum contains anti-H. The proband was assigned as B/O1 by ABO genotyping. Two new heterozygous mutations of FUT1 gene, c.508dupT and c.787A>C, were identified through direct sequencing of PCR-amplified products. TA cloning and sequencing confirmed that two novel mutations were on different alleles. FUT2 gene sequence of the proband is consistent with standard. The other family members of the proband showed normal phenotypes of ABO blood group and their genotypes are consistent with phenotypes.

CONCLUSION

Two novel FUT1 alleles, with the previously not reported mutations c.508dupT and c.787C, respectively, are responsible for the para-Bombay phenotype detected in the sample from the proband.

Host Synthesized Carbohydrate Antigens on Viral Glycoproteins as "Achilles' Heel" of Viruses Contributing to Anti-Viral Immune Protection

The glycans on enveloped viruses are synthesized by host-cell machinery. Some of these glycans on zoonotic viruses of mammalian reservoirs are recognized by human natural antibodies that may protect against such viruses. These antibodies are produced mostly against carbohydrate antigens on gastrointestinal bacteria and fortuitously, they bind to carbohydrate antigens synthesized in other mammals, neutralize and destroy viruses presenting these antigens. Two such antibodies are: anti-Gal binding to α-gal epitopes synthesized in non-primate mammals, lemurs, and New World monkeys, and anti-N-glycolyl neuraminic acid (anti-Neu5Gc) binding to N-glycolyl-neuraminic acid (Neu5Gc) synthesized in apes, Old World monkeys, and many non-primate mammals. Anti-Gal appeared in Old World primates following accidental inactivation of the α1,3galactosyltransferase gene 20–30 million years ago. Anti-Neu5Gc appeared in hominins following the inactivation of the cytidine-monophosphate-N-acetyl-neuraminic acid hydroxylase gene, which led to the loss of Neu5Gc <6 million-years-ago. It is suggested that an epidemic of a lethal virus eliminated ancestral Old World-primates synthesizing α-gal epitopes, whereas few mutated offspring lacking α-gal epitopes and producing anti-Gal survived because anti-Gal destroyed viruses presenting α-gal epitopes, following replication in parental populations. Similarly, anti-Neu5Gc protected few mutated hominins lacking Neu5Gc in lethal virus epidemics that eliminated parental hominins synthesizing Neu5Gc. Since α-gal epitopes are presented on many zoonotic viruses it is suggested that vaccines elevating anti-Gal titers may be of protective significance in areas endemic for such zoonotic viruses. This protection would be during the non-primate mammal to human virus transmission, but not in subsequent human to human transmission where the virus presents human glycans. In addition, production of viral vaccines presenting multiple α-gal epitopes increases their immunogenicity because of effective anti-Gal-mediated targeting of vaccines to antigen presenting cells for extensive uptake of the vaccine by these cells.

Human Natural Antibodies to Mammalian Carbohydrate Antigens as Unsung Heroes Protecting against Past, Present, and Future Viral Infections

Human natural antibodies to mammalian carbohydrate antigens (MCA) bind to carbohydrate-antigens synthesized in other mammalian species and protect against zoonotic virus infections. Three such anti-MCA antibodies are: (1) anti-Gal, also produced in Old-World monkeys and apes, binds to α-gal epitopes synthesized in non-primate mammals, lemurs, and New-World monkeys; (2) anti-Neu5Gc binds to Neu5Gc (N-glycolyl-neuraminic acid) synthesized in apes, Old-World monkeys, and many non-primate mammals; and (3) anti-Forssman binds to Forssman-antigen synthesized in various mammals. Anti-viral protection by anti-MCA antibodies is feasible because carbohydrate chains of virus envelopes are synthesized by host glycosylation machinery and thus are similar to those of their mammalian hosts. Analysis of MCA glycosyltransferase genes suggests that anti-Gal appeared in ancestral Old-World primates following catastrophic selection processes in which parental populations synthesizing α-gal epitopes were eliminated in enveloped virus epidemics. However, few mutated offspring in which the α1,3galactosyltransferase gene was accidentally inactivated produced natural anti-Gal that destroyed viruses presenting α-gal epitopes, thereby preventing extinction of mutated offspring. Similarly, few mutated hominin offspring that ceased to synthesize Neu5Gc produced anti-Neu5Gc, which destroyed viruses presenting Neu5Gc synthesized in parental hominin populations. A present-day example for few humans having mutations that prevent synthesis of a common carbohydrate antigen (produced in >99.99% of humans) is blood-group Bombay individuals with mutations inactivating H-transferase; thus, they cannot synthesize blood-group O (H-antigen) but produce anti-H antibody. Anti-MCA antibodies prevented past extinctions mediated by enveloped virus epidemics, presently protect against zoonotic-viruses, and may protect in future epidemics. Travelers to regions with endemic zoonotic viruses may benefit from vaccinations elevating protective anti-MCA antibody titers.

Immunohematological study of the first pediatric patient with the Bombay phenotype in Medellín, Colombia

The Bombay (Oh) phenotype is a rare phenotype in which red blood cells lack the H antigen as a result of a point mutation in the H gene. Oh patients are a challenge in transfusion medicine. We present a case of a pediatric patient with the Bombay phenotype who was carried to the emergency department of the Hospital Universitario San Vicente Fundación in Medellín, Colombia. The patient presented gastrointestinal hemorrhage and required transfusion therapy. Pretransfusion and molecular immunohematological analyses identified the Bombay phenotype. The patient was transfused with Oh red blood cells imported to Colombia from the Hematology and Hemotherapy Center of Ceará (Hemoce) in Fortaleza, Brazil. This first case of an Oh individual in Colombia highlights the need to look for donors with rare phenotypes to fulfill the transfusion requirements of the population.

Mutational Analysis of Bombay Phenotype in Iranian People: Identification of a Novel FUT1 Allele

Bombay phenotype is characterized by lack of ABH antigens on RBCs and in body secretions as a result of mutations in fucosyltransferase 1 (FUT1) and fucosyltransferase 2 (FUT2) genes. The aim of this study was a mutational analysis in Iranians with this phenotype. Serological analyses including ABH and adsorption-elution tests were performed in five unrelated Bombay individuals. ABO genotyping was determined by direct sequencing. The coding regions of FUT1 and FUT2 genes were amplified and sequenced directly or after cloning into suitable vector. A novel missense FUT1 allele was detected (G1051T; G351C). Also four reported FUT1 alleles were revealed. Molecular analysis of FUT2 gene confirmed nonsecretor status in all individuals. This and our previous findings suggest the diversity and population specificity of FUT1 alleles.

ABO phenotype-protected reproduction based on human specific α1,2 L-fucosylation as explained by the Bombay type formation

The metabolic relationship between the formation of the ABO(H) blood group phenotype and human fertility is evident in the case of the (Oh) or Bombay blood type, which Charles Darwin would have interpreted as resulting from reduced male fertility in consanguinities, based on the history of his own family, the Darwin/Wedgwood Dynasty. The classic Bombay type occurs with the extremely rare, human-specific genotype (h/h; se/se), which (due to point mutations) does not encode fucosyltransferases 1(FUT1) and 2 (FUT2). These enzymes are the basis for ABO(H) phenotype formation on the cell surfaces and fucosylation of plasma proteins, involving neonatal immunoglobulin M (IgM). In the normal human blood group O(H), which is not protected by clonal selection with regard to environmental A/B immunization, the plasma contains a mixture of non-immune and adaptive anti-A/B reactive isoagglutinins, which in the O(h) Bombay type show extremely elevated levels, associated with decreased levels of fucosylation-dependent functional plasma proteins, suchs as the van Willebrand factor (vWF) and clotting factor VIII. In fact, while the involvement of adaptive immunoglobulins remains unknown, poor fucosylation may explain the polyreactivity in the Bombay type plasma, which exhibits pronounced complement-binding cross-reactive anti-A/Tn and anti-B IgM levels, with additional anti-H reactivity, acting over a wide range of temperatures, with an amplitude at 37 °C. This aggressive anti-glycan-reactive IgM molecule suggests the induction of ADCC (antibody-dependent) and/or complement-mediated cytotoxicity via overexpressed glycosidic bond sites against the embryogenic stem cell-to-germ cell transformation, which is characterized by fleeting appearances of A-like, developmental trans-species GalNAcα1-O-Ser/Thr-R glycan, also referred to as the Tn (T "nouvelle") antigen.

A Very Rare Case with Particular H-deficient Phenotypes

Bombay phenotype, H partially deficient non secretor phenotype and Para-Bombay phenotype are rare blood groups with deficiency or absence of H antigen. A 52-year-old female with Chronic suppurative otitis media was referred to our hospital. The primary serologic results of ABO blood typing were discrepant in forward and reverse grouping. Further, the saliva secretion tests, the pedigree studies and the sequence analysis were performed to confirm the rare phenotype. The patient was diagnosed as a variant H-deficient phenotype, secretor (para-bombay). Red cells of the patient have no H antigens, and it's a very interesting thing that there were two opposite results in the saliva test by using different anti-H. The test showed that H substances were present in the saliva by using anti-H from Libo Biotechnology Co, while which were absent by using anti-H from Shanghai blood center. The patient's Lewis phenotype was Le (a-b+). Anti-HI was present in the sera of her. The sequence of the ABO gene of the patient was 261delG and 467C>T heterozygote by direct DNA sequencing and was assigned as A102/O01. There were two mutations of the patient's FUT1, 328G/A and 658C/T, which were identified by DNA sequencing compared with the reference sequence (GenBank, NG_007510.2). In this case, we report a patient with particular H-deficient phenotype, secretor, which showed opposite results in the saliva test by using anti-H from different sources. We suspect that it is a variant of para-Bombay phenotype.

Identification of a novel FUT1 allele with two mutations in a Chinese para-Bombay individual

BACKGROUND

The para-Bombay phenotype often results from a silenced β-D-galactoside 2-α-fucosyltransferase 1 (FUT1) gene (h/h) but an active FUT2 (Se/Se or Se/se) gene. We identified a para-Bombay phenotype with two novel mutations in the FUT1 gene and homozygous mutated FUT2 (se357, 385 /se357, 385 ) genes.

STUDY DESIGN AND METHODS

Red blood cell phenotype was detected by using a standard serologic technique. The entire coding regions of the FUT1 and FUT2 genes were amplified and direct sequenced using genomic DNA.

RESULTS

No ABH substance was detected on the surface of the proband's red blood cells. Anti-A, anti-B, and anti-H were identified in serum. Genetic studies indicated that the proband's ABO genotyping was A102/O01 and that the FUT2 phenotype was se357, 385 /se357,385 . The sample was homozygous for two FUT1 mutations: c.958insG and c.961G > A.

CONCLUSION

Two novel FUT1 mutations have been identified in the proband's FUT1 gene. The insertion mutation in the FUT1 that caused a shift of the open reading frame and formed a termination codon early at Amino Acid Position 334 may be the main reason for H deficiency in this case.

Molecular basis of Bombay phenotype in Mashhad, Iran: identification of a novel FUT1 deletion

BACKGROUND AND OBJECTIVES

Bombay phenotype is characterized by the lack of H substance both on red blood cell (RBC) surface and in body secretions. Mutations of fucosyltransferase 1 (FUT1) and fucosyltransferase 2 (FUT2) genes are resulted in this rare phenotype.

MATERIALS AND METHODS

Five unrelated patients were tested by hemagglutination and adsorption/elution techniques for the presence of ABH antigens. The saliva specimens were analysed by hemagglutination inhibition method. The exons 6 and 7 of ABO gene were sequenced to determine ABO genotype. The coding fragments of FUT1 and FUT2 were amplified and sequenced by specific primers.

RESULTS

Serologic investigation confirmed Bombay phenotype in all individuals. FUT1 molecular analysis revealed a novel large deletion. Also two novel homozygous mutations were detected; one was a missense mutation (392T>C, L131P) and the other a three nucleotide deletion (668_670delACT, Y224del). FUT2 sequencing showed one reported null allele (428G>A, W143X) and one homozygous deletion of FUT2.

CONCLUSION

Although FUT2 deletion has been reported, this is the first report of FUT1 deletion. Finding two FUT1 novel alleles in Iranian people is indicative of mutation diversity in this gene.

Decoding norovirus infection in Crohn's disease

Although a causing viral infectious agent remains untraceable in Crohn's disease, most recent genome-wide association studies have linked the FUT2 W143X mutation (resulting in asymptomatic norovirus infection) with the pathogenesis of Crohn's ileitis and with vitamin B12 deficiency (i.e., a known risk factor for Crohn's disease with ileal involvement). In line with these findings, host variations in additional genes involved in host response to norovirus infection (such as ATG16L1 and NOD2) predispose humans to Crohn's ileitis. One may therefore presume that asymptomatic norovirus infection may contribute to disruption of the stability of the gut microbiota leading to Crohn's ileitis. These paradigms highlight not only the need to revisit the potential transmissibility of Crohn's disease, but also potential safety issues of forthcoming clinical trials on human probiotic infusions in Crohn's ileitis by rigorous donors screening program.

Structural basis for the recognition of Lewis antigens by genogroup I norovirus

Noroviruses (NoVs) bind to histo-blood group antigens, namely, ABH antigens and Lewis antigens. We previously showed the NoVs GI/2, GI/3, GI/4, and GI/8 were able to strongly bind to Lewis a (Le(a)) antigen, which is expressed by individuals who are nonsecretors. In this study, to investigate how Lewis antigens interact with GI NoV virion protein 1 (VP1), we determined the crystal structures of the P domain of the VP1 protein from the Funabashi 258 (FUV258) strain (GI/2) in complexes with Le(a), Le(b), H type 1, or A type 1 antigens. The structures were compared with those of the NV/68 strain (GI/1), which does not bind to the Le(a) antigen. The four loop structures, loop P, loop S, loop A, and loop B, continuously deviated by more than 2 Å in length between the Cα atoms of the corresponding residues of the FUV258 and NV/68 P domains. The most pronounced differences between the two VP1 proteins were observed in the structures of loop P. In the FUV258 P domain, loop P protruded toward the next protomer, forming a Le(a) antigen-binding site. The Gln389 residue make a significant contribution to the binding of the Le(a) antigen through the stabilization of loop P as well as through direct interactions with the α4-fucosyl residue (α4Fuc) of the Le(a) antigen. Mutation of the Gln389 residue dramatically affected the degree of binding of the Lewis antigens. Collectively, these results suggest that loop P and the amino acid residue at position 389 affect Lewis antigen binding.

C35T mutation could slightly decrease the activity of human α-(1,2)-fucosyltransferase

PURPOSE OF THE STUDY

The C35T mutant α-(1,2)-fucosyltransferase (FUT1) gene had been reported related to the para-Bombay phenotype, but recently, our laboratory found that the C35T was a polymorphism in the Chinese population. This study aims at further clarifying the property of C35T mutant FUT1.

MATERIAL AND METHODS

The mutant C35T FUT1 gene was cloned into expression vector in vitro, the mRNA expression was analyzed by real-time quantitative polymerase chain reaction (PCR), and the mutant enzyme's activity was determined in vitro.

RESULTS

The results showed that the frequencies of 35C and 35T alleles were 0.735 and 0.265, respectively. The FUT1 mRNA level of transfected cells with C35T recombination vector showed 99.85% of the wild-type FUT1 transfected cells. The enzyme relative activity of transfected cell lysates with C35T FUT1 recombination vector was 79.45% compared with that of the wild-type FUT1 transfected cell lysates. The K(m)(phenyl-gal) value of enzyme encoded by C35T allele was 0.5 times higher than that of the enzyme encoded by FUT1 wild-type allele.

CONCLUSION

These results suggested that FUT1 C35T was a polymorphism in the Chinese population and did not affect its mRNA transcription, but could slightly decrease the activity of human α-(1,2)-fucosyltransferase in vitro.

A novel FUT1 allele was identified in a Chinese individual with para-Bombay phenotype

BACKGROUND

The para-Bombay phenotype is characterised by H-deficient or H partially deficient red blood cells (RBCs) in individuals who secrete ABH antigens in their saliva. Samples from an individual whose RBCs had an apparent para-Bombay phenotype and his family members were investigated and a novel FUT1 allele was identified.

MATERIALS AND METHODS

RBCs' phenotype was characterised by standard serologic technique. Genomic DNA was sequenced with primers that amplified the coding sequence of FUT1 and FUT2, respectively. Routine ABO genotyping analysis was performed. Haplotypes of FUT1 were identified by TOPO cloning sequencing. Recombination expression vectors of FUT1 mutation alleles were constructed and transfected into COS-7 cells. The pα-(1,2)-fucosyltransferase activity of expression protein was determined.

RESULTS

B101/O02 genotype of the proband was correlated with ABH substances in saliva. The proband carried a new FUT1 allele which showed 35C/T, 235G/C and 682A/G heterozygote by directly DNA sequencing. Two haplotypes, 235C and 35T+682G, were identified by TOPO cloning sequencing and COS-7 cells transfected with five recombination vectors including wild-type, 35T, 235C, 682G and 35T+682G alleles were established respectively. The α-(1,2)-fucosyltransferase activities of cell lysates which had transfected with 35T, 235C, 682G and 35T+682G recombination vectors showed 79·45, 16·23, 80·32 and 24·59%, respectively, compared with that of the wild-type FUT1-transfected cell lysates.

CONCLUSION

A novel FUT1 allele 235C was identified, which greatly diminished the activity of α-(1,2)-fucosyltransferase.

Generation of human induced pluripotent stem cells from a Bombay individual: moving towards "universal-donor" red blood cells

Bombay phenotype is one of the rare phenotypes in the ABO blood group system that fails to express ABH antigens on red blood cells. Nonsense or missense mutations in fucosyltransfrase1 (FUT1) and fucosyltransfrase2 (FUT2) genes are known to create this phenotype. This blood group is compatible with all other blood groups as a donor, as it does not express the H antigen on the red blood cells. In this study, we describe the establishment of human induced pluripotent stem cells (iPSCs) from the dermal fibroblasts of a Bombay blood-type individual by the ectopic expression of established transcription factors Klf4, Oct4, Sox2, and c-Myc. Sequence analyses of fibroblasts and iPSCs revealed a nonsense mutation 826C to T (276 Gln to Ter) in the FUT1 gene and a missense mutation 739G to A (247 Gly to Ser) in the FUT2 gene in the Bombay phenotype under study. The established iPSCs resemble human embryonic stem cells in morphology, passaging, surface and pluripotency markers, normal karyotype, gene expression, DNA methylation of critical pluripotency genes, and in-vitro differentiation. The directed differentiation of the iPSCs into hematopoietic lineage cells displayed increased expression of the hematopoietic lineage markers such as CD34, CD133, RUNX1, KDR, alpha-globulin, and gamma-globulin. Such specific stem cells provide an unprecedented opportunity to produce a universal blood group donor, in-vitro, thus enabling cellular replacement therapies, once the safety issue is resolved.

Noroviruses distinguish between type 1 and type 2 histo-blood group antigens for binding

Norovirus (NoV) is a causative agent of acute gastroenteritis. NoV binds to histo-blood group antigens (HBGAs), namely, ABH antigens and Lewis (Le) antigens, in which type 1 and type 2 carbohydrate core structures constitute antigenically distinct variants. Norwalk virus, the prototype strain of norovirus, binds to the gastroduodenal junction, and this binding is correlated with the presence of H type 1 antigen but not with that of H type 2 antigen (S. Marionneau, N. Ruvoen, B. Le Moullac-Vaidye, M. Clement, A. Cailleau-Thomas, G. Ruiz-Palacois, P. Huang, X. Jiang, and J. Le Pendu, Gastroenterology 122:1967-1977, 2002). It has been unknown whether NoV distinguishes between the type 1 and type 2 chains of A and B antigens. In this study, we synthesized A type 1, A type 2, B type 1, and B type 2 pentasaccharides in vitro and examined the function of the core structures in the binding between NoV virus-like particles (VLPs) and HBGAs. The attachment of five genogroup I (GI) VLPs from 5 genotypes and 11 GII VLPs from 8 genotypes, GI/1, GI/2, GI/3, GI/4, GI/8, GII/1, GII/3, GII/4, GII/5, GII/6, GII/7, GII/12, and GII/14, to ABH and Le HBGAs was analyzed by enzyme-linked immunosorbent assay-based binding assays and Biacore analyses. GI/1, GI/2, GI/3, GI/4, GI/8, and GII/4 VLPs were more efficiently bound to A type 2 than A type 1, and GI/8 and GII/4 VLPs were more efficiently bound to B type 2 than B type 1, indicating that NoV VLPs distinguish between type 1 and type 2 carbohydrates. The dissociation of GII/4 VLPs from B type 1 was slower than that from B type 2 in the Biacore experiments; moreover, the binding to B type 1 was stronger than that to B type 2 in the ELISA experiments. These results indicated that the type 1 carbohydrates bind more tightly to NoV VLPs than the type 2 carbohydrates. This property may afford NoV tissue specificity. GII/4 is known to be a global epidemic genotype and binds to more HBGAs than other genotypes. This characteristic may be linked with the worldwide transmission of GII/4 strains. GI/2, GI/3, GI/4, GI/8, GII/4, and GII/7 VLPs bound to Le(a) expressed by nonsecretors, suggesting that NoV can infect individuals regardless of secretor phenotype. Overall, our results indicated that HBGAs are important factors in determining tissue specificity and the risk of transmission.

Genetic mechanisms for the synthesis of fucosyl GM1 in small cell lung cancer cell lines

Fucosyl GM1 has been reported to be specifically expressed in small cell lung cancer (SCLC) cells. However, the genetic basis for the synthesis of fucosyl GM1 has not been investigated. We analyzed the glycosyltransferases responsible for the synthesis of fucosyl GM1 in SCLC cell lines. In four SCLC cell lines expressing fucosyl GM1, both FUT1 and FUT2 mRNAs were detected, indicating that either one or both of alpha1,2-fucosyltransferases may be involved in the expression of fucosyl GM1. However, three of these four lines contained function-loss mutations in the FUT2 coding region, suggesting that FUT1 is mainly involved in the alpha1,2-fucosylation of GM1. The expression levels of the GM1 synthase gene showed no correlation with those of fucosyl GM1, whereas the co-transfection of GM1 synthase cDNA with FUT1 or FUT2 into SK-LC-17 clearly enhanced the neo-expression of fucosyl GM1, indicating its essential role. In contrast, the co-transfection of GD3 synthase cDNA reduced the expression levels of fucosyl GM1 with FUT1 or FUT2. Consequently, FUT1 seems to mainly contribute to the expression of fucosyl GM1, although both FUT1 and FUT2 are capable of generating the antigen. These results should promote the functional analysis of fucosyl GM1 leading to the development of novel therapies for SCLC.

The fusion allele of the FUT2 (secretor type alpha(1,2)-fucosyltransferase) gene at a high frequency and a new se385 allele in a Korean population

The fusion gene (se(fus)), a nonfunctional allele of the FUT2 [secretor type alpha(1,2)-fucosyltransferase] gene, was found in Japanese populations with high frequencies (4.8-7.9%). In a study on a Korean population, se(fus) was found at a very low frequency (0.6%), but it has not yet been revealed in any other ethnic population. The aim of the present study was to investigate FUT2 gene polymorphisms in a Korean population and to evaluate their implications in secretor expression in saliva. We investigated the frequency of the FUT2 alleles in a Korean population via polymerase chain reaction with confronting two-pair primers (PCR-CTPP) and restriction fragment length polymorphism (PCR-RFLP). Blood samples were collected from 348 random donors in Bundang Koreans. From a total of 696 alleles examined, the frequency of the se(fus) allele in the Korean population was 10.8%. In addition, the new se385 allele was found in about 7.2% of the subjects, an unusually frequent occurrence compared to any other population investigated so far. The null alleles of the FUT2 gene are another example of rare alleles occurring with unexpectedly high frequencies in distinct geographic regions or populations.

Molecular basis for para-Bombay phenotypes in Chinese persons, including a novel nonfunctional FUT1 allele

BACKGROUND

The para-Bombay phenotype is characterized by H-deficient or H-partially deficient red blood cells (RBCs) in persons who secrete ABH antigens in their saliva. The studies that determined the genotypes for two Chinese individuals with the para-Bombay phenotype are described.

STUDY DESIGN AND METHODS

RBC phenotypes were characterized by conventional serologic methods. Exons 6 and 7 of the ABO gene were amplified, as well as the entire coding region for FUT1 and FUT2, with four independence polymerase chain reactions (PCRs) from genomic DNA. PCR products were excised, purified from agarose gels, and sequenced directly. Mutations of FUT1 were identified by TOPO cloning sequencing.

RESULTS

For both individuals, RBC ABO genotypes correlated with ABH substances in their saliva. One individual (a patient) had two heterozygous mutations of FUT1 by direct DNA sequencing, namely, a C-->T heterozygous mutation at position 293(C293T) and AG heterozygous deletion (CAGAGAG-->CAGAG) at position 547 to 552. These two mutations were confirmed to be compound heterozygotes; that is, each mutation was determined to be on a separate homologous chromosome by TOPO cloning sequencing. The FUT2 genotype was Se(357)Se(357). The other individual (a blood donor) had an AG deletion at position 547 to 552 homozygous allele in FUT1. The FUT2 genotype was Se(357)Se(357,385). C293T mutation can cause Thr/Met at amino acid position 98. AG deletion at position 547 to 552 caused a reading frameshift and a premature stop codon.

CONCLUSION

A novel nonfunctional FUT1 allele C293T was identified in a person with the para-Bombay phenotype. This rare H-deficient phenotype may result from different nonfunctional alleles.

The blood group P1 synthase gene is identical to the Gb3/CD77 synthase gene. A clue to the solution of the P1/P2/p puzzle

Blood group P1/P2 is a glycolipid antigen system for which the genetic mechanism has not yet been clarified. We analyzed the potential of the cloned Gb3/CD77 synthase to synthesize P1 antigen, because Gb3/CD77 and P1 share a common structure, Galalpha1,4Galbeta1,4Glc (NAc)-. L cell transfectants with Gb3/CD77 synthase cDNA expressed marginal levels of P1 on the cell surface but contained high levels of P1 in the cytoplasm. P2-type erythrocytes, which were serotyped as P2, also contained definite P1 antigen inside cells, although the amounts were lower than those of P1 cells. Only p erythrocytes lacked P1 antigen corresponding with function-losing mutations in the Gb3/CD77 synthase gene. Synthesis of P1 antigen from paragloboside in vitro was demonstrated using membrane fraction of the transfectants and a fusion enzyme with protein A. These results strongly suggested that P1 synthase is identical to Gb3/CD77 synthase and appear to propose a clue for the solution of the long-pending P1/P2/p puzzle. The P1/P2 difference might result from the difference in P1 quantity based on either different enzyme activity or the presence/absence of other enzyme modulators. Because P2 erythrocytes showed lower levels of Gb3/CD77 synthase mRNA than P1, 5'-upstream promoter regions were analyzed, resulting in the identification of two P2-specific homozygous mutations. Differences in the transcriptional regulation in erythrocytes might be a major factor determining P1/P2.

Molecular genetic analysis of para-Bombay phenotypes in Chinese: a novel non-functional FUT1 allele is identified

BACKGROUND AND OBJECTIVES

The para-Bombay phenotype (also known as H-deficient secretor) is characterized by a lack of ABH antigens on red cells, but ABH substances are found in saliva. Molecular genetic analysis was performed for five Chinese individuals serologically typed as para-Bombay.

MATERIALS AND METHODS

ABO genotyping and mutational analysis of both FUT1 (or H) and FUT2 (or Se) loci were performed for these individuals using the polymerase chain reaction, single-strand conformation polymorphism analysis and direct DNA sequencing.

RESULTS

The ABO genotypes of these para-Bombay individuals correlated with the types of ABH substances found in the saliva. Their FUT1 genotypes were h1h2 (three individuals), h2h2 (one individual) and h2h6 (one individual). Alleles h1 (547-552delAG) and h2 (880-882delTT) were known frameshift mutations, while h6 (522C > A) was a missense mutation (Phe174Leu) not previously reported. These three mutations were rare sequence variations, each with an allele frequency of less than 0.005. Phe174 might be functionally important because this residue is conserved from mouse to human. Their FUT2 genotypes were Se357se357,385 for the h2h6 individual and Se357Se357) for the others. Both FUT2 alleles were known: one functional (Se357) and one weakly functional (se357,385). That they carried at least one copy of a functional FUT2 allele was consistent with their secretor status. As FUT1 and FUT2 are adjacent on 19q13.3, there are three possible haplotypes in these para-Bombay individuals: h1-Se357; h2-Se357; and h6-se357,385.

CONCLUSIONS

A novel non-functional FUT1 allele (522C > A, or Phe174Leu) was identified in a para-Bombay individual and on a se357,385 haplotype background.

The polymorphisms of fucosyltransferases

The alpha(1,2)fucosyltransferase Se enzyme regulates the expression of the ABH antigens in secretion. Secretors, who have ABH antigens in their saliva, have at least one functional Se allele in the FUT2 locus, while non-secretors, who fail to express ABH antigens in saliva, are homozygous for the non-functional se allele. Molecular analyses of the FUT2 polymorphism of various populations have indicated the ethnic specificity of null alleles: the null allele se(428) is a common Se enzyme-deficient allele in Africans and Caucasians but does not occur in Asians, whereas the null allele se(357,385) is specific to Asians. The gene frequency of se(428) or se(357,385) is about 0.5 in each respective population. Why the se(428) is absent in Asians is of interest. Also here, we describe the polymorphisms of the fucosyltransferase genes (FUT1, FUT3 and FUT6).

Treatment of acute myeloblastic leukaemia in a patient with Bombay blood type: a case report

A 62-year-old female was admitted to our hospital with suspected acute leukaemia and after investigation we diagnosed acute myeloblastic leukaemia (AML-M1). The patient's blood type was found to be the very rare Bombay type and surveillance of her relatives showed the same blood type in her male cousin on her mother's side. Alongside chemotherapy the patient received 4000 ml of frozen Bombay-type red cells, 1400 ml of concentrated red cells in manitol adenine phosphate solutions and 360 units of type O concentrated platelets without marked effects. The anti-H antibody was initially at 128 dilution but for unknown reasons increased to 2048 dilution after remission of AML-M1. About 3 months after hospitalization the patient died of Cryptococcus neoformans pneumonia despite strict precautions against infection. Although AML-M1 is a common adult leukaemia and is chemosensitive to anti-leukaemic drugs, neither AML-M1 in a patient with Bombay-type red cells nor its treatment with chemotherapy and transfusion with type Oh frozen red cells have previously been reported.

A new h allele detected in Europe has a missense mutationin alpha(1,2)-fucosyltransferase motif II

BACKGROUND

The FUT1 gene encodes an alpha(1,2)-fucosyltransferase (H transferase), which determines the blood group H. Nonfunctional alleles of this gene, called h alleles and carrying loss-of-function mutations, are observed in the exceedingly rare Bombay phenotype. Twenty-three distinct h alleles have been characterized at the molecular level in various populations. The FUT2 (SE) gene is highly homologous to FUT1 (H:).

STUDY DESIGN AND METHODS

The FUT1 gene of an Austrian proband with the Bombay phenotype was characterized by nucleotide sequencing of the full-length coding sequence. A PCR method using sequence-specific primers for FUT2 genotyping in whites was developed. The plasma alpha(1,2)-fucosyltransferase activity was determined. The distribution of the mutations underlying 24 h alleles and 7 se alleles was analyzed.

RESULTS

The proband carried a new h allele. Two nucleotide changes, G785A and C786A, in codon 262 of the FUT1 gene resulted in the replacement of serine by lysine. No alpha(1,2)-fucosyltransferase activity was detected in the proband's plasma. The proband was homozygous for the seG428A allele. Six of 17 missense mutations in nonfunctional h and se alleles occurred in highly conserved fucosyltransferase motifs. No loss-of-function mutation was observed in the aminoterminal section encompassing the transmembraneous helix.

CONCLUSION

The missense mutation S262K in the FUT1 gene caused the loss of H transferase activity. The analysis of the distribution of mutations in nonfunctional FUT1 and FUT2 genes can point to functionally important domains in the H transferase.

Evolution of alpha 2-fucosyltransferase genes in primates: relation between an intronic Alu-Y element and red cell expression of ABH antigens

Coding sequences of the paralogous FUT1 (H), FUT2 (Se), and Sec1 alpha 2-fucosyltransferase genes were obtained from different primate species. Analysis of the primate FUT1-like and FUT2-like sequences revealed the absence of the known human inactivating mutations giving rise to the h null alleles of FUT1 and the se null alleles of FUT2. Therefore, most primate FUT1-like and FUT2-like genes potentially code for functional enzymes. The Sec1-like gene encodes for a potentially functional alpha 2-fucosyltransferase enzyme in nonprimate mammals, New World monkeys, and Old World monkeys, but it has been inactivated by a nonsense mutation at codon 325 in the ancestor of humans and African apes (gorillas, chimpanzees). Human and gorilla Sec1's have, in addition, two deletions and one insertion, respectively, 5' of the nonsense mutation leading to proteins shorter than chimpanzee Sec1. Phylogenetic analysis of the available H, Se, and Sec1 mammalian protein sequences demonstrates the existence of three clusters which correspond to the three genes. This suggests that the differentiation of the three genes is rather old and predates the great mammalian radiation. The phylogenetic analysis also suggests that Sec1 has a higher evolutionary rate than FUT2 and FUT1. Finally, we show that an Alu-Y element was inserted in intron 1 of the FUT1 ancestor of humans and apes (chimpanzees, gorillas, orangutans, and gibbons); this Alu-Y element has not been found in monkeys or nonprimate mammals, which lack ABH antigens on red cells. A potential mechanism leading to the red cell expression of the H enzyme in primates, related to the insertion of this Alu-Y sequence, is proposed.

Molecular mechanisms of expression of Lewis b antigen and other type I Lewis antigens in human colorectal cancer

Lewis b (Leb) antigens are gradiently expressed from the proximal to the distal colon, i.e., they are abundantly expressed in the proximal colon, but only faintly in the distal colon. In the distal colon, they begin to increase at the adenoma stage of cancer development and then increase with cancer progression. We aimed to clarify the molecular basis of Leb antigen expression in correlation with the expression of other type I Lewis antigens, such as Lewis a (Lea) and sialylated Lewis a (sLea), in colon cancer cells. Considering the Se genotype and the relative activities of the H and Se enzymes, the amounts of Leb antigens were proved to be determined by both the H and Se enzymes in noncancerous and cancerous colon tissues. But the Se enzyme made a much greater contribution to determining the Lebamounts than the H enzyme. In noncancerous colons, the Se enzyme were gradiently expressed in good correlation with the Leb expression, while the H enzyme was constantly expressed throughout the whole colon. In distal colon cancers, the H and Se enzymes were both significantly upregulated in comparison with in adjacent noncancerous tissues. In proximal colon cancers, expression of the H enzyme alone was highly augmented. The augmented expression of Leb antigens in distal colon cancers is caused mainly by upregulation of the Se enzyme and partly by the H enzymes, while it is caused by upregulation of the H enzyme alone in proximal colon cancers. The Se gene dosage profoundly influences the amounts of the Leb, Lea, and sLea antigens in whole colon tissues, regardless of whether they are noncancerous or cancerous tissues. It suggests that the Se enzyme competes with alpha2,3 sialyltransferase(s) and the Le enzyme for the type I acceptor substrates.

Expression cloning and characterization of a novel murine alpha1, 3-fucosyltransferase, mFuc-TIX, that synthesizes the Lewis x (CD15) epitope in brain and kidney

The 3-fucosyl-N-acetyllactosamine (Lewis x, CD15, SSEA-1) carbohydrate epitope is widely distributed in many tissues and is developmentally expressed in some rodent and human tissues, i.e. brain and lung, and mouse early embryo. In such tissues, the Lewis x epitope is considered to be involved in cell-cell interactions. We isolated a novel mouse alpha1,3-fucosyltransferase gene, named mFuc-TIX, from an adult mouse brain cDNA library using the expression cloning method. On flow cytometric analysis, Namalwa cells transfected stably with the mFuc-TIX gene showed a marked increase in Lewis x epitopes but not sialyl Lewis x epitopes. As seen experiments involving oligosaccharides as acceptor substrates, mFuc-TIX transfers a fucose to lacto-N-neotetraose but not to either alpha2,3-sialyl lacto-N-neotetraose or lacto-N-tetraose. The substrate specificity of mFuc-TIX was similar to that of mouse myeloid-type alpha1,3-fucosyltransferase (mFuc-TIV). The deduced amino acid sequence of mFuc-TIX, consisting of 359 residues, indicated a type II membrane protein and shows low degrees of homology to the previously cloned alpha1,3-fucosyltransferases, i.e. mFuc-TIV (48.4%), mouse Fuc-TVII (39.1%), and human Fuc-TIII (43.0%), at the amino acid sequence level. A phylogenetic tree of the alpha1, 3-fucosyltransferases constructed by the neighbor-joining method showed that mFuc-TIX is quite distant from the other alpha1, 3-fucosyltransferases. Thus, mFuc-TIX does not belong to any subfamilies of known alpha1,3Fuc-Ts. The mFuc-TIX transcript was mainly detected in brain and kidney with the Northern blotting and competitive reverse transcription-polymerase chain reaction methods, whereas the mFuc-TIV transcript was not detected in brain with these methods. On in situ hybridization, the mFuc-TIX transcript was detected in neuronal cells but not in the glial cells including astrocytes. These results strongly indicated that mFuc-TIX participates in the Lewis x synthesis in neurons of the brain and may be developmentally regulated.

Conserved structural features in eukaryotic and prokaryotic fucosyltransferases

Fucosyltransferases are the enzymes transferring fucose from GDP-Fuc to Gal in an alpha1,2-linkage and to GlcNAc in alpha1,3-, alpha1,4-, or alpha1,6-linkages. Since all fucosyltransferases utilize the same nucleotide sugar, their specificity will probably reside in the recognition of the acceptor and in the type of linkage formed. A search of nucleotide and protein databases yielded more than 30 sequences of fucosyltransferases originating from mammals, chicken, nematode, and bacteria. On the basis of protein sequence similarities, these enzymes can be classified into four distinct families: (1) the alpha-2-fucosyltransferases, (2) the alpha-3-fucosyltransferases, (3) the mammalian alpha-6-fucosyltransferases, and (4) the bacterial alpha-6-fucosyltransferases. Nevertheless, using the sensitive hydrophobic cluster analysis (HCA) method, conserved structural features as well as a consensus peptide motif have been clearly identified in the catalytic domains of all alpha-2 and alpha-6-fucosyltranferases, from prokaryotic and eukaryotic origin, that allowed the grouping of these enzymes into one superfamily. In addition, a few amino acids were found strictly conserved in this family, and two of these residues have been reported to be essential for enzyme activity for a human alpha-2-fucosyltransferase. The alpha-3-fucosyltransferases constitute a distinct family as they lack the consensus peptide, but some regions display similarities with the alpha-2 and alpha-6-fucosyltranferases. All these observations strongly suggest that the fucosyltransferases share some common structural and catalytic features.

Missense mutation of FUT1 and deletion of FUT2 are responsible for Indian Bombay phenotype of ABO blood group system

The Bombay phenotype fails to express the ABH antigens of ABO blood group system on red blood cells and in secretions because of a lack in activities of the H gene (FUT1)- and Secretor gene (FUT2)-encoded alpha (1,2)fucosyltransferases. In this study, we have examined the FUT1 and the FUT2 from three unrelated Indian individuals with the Bombay phenotype. These three individuals were found to be homozygous for a T725G mutation in the coding region of the FUT1, which inactivated the enzyme activity. In addition, we did not detect any hybridized band corresponding to the FUT2 by Southern blot analysis using the catalytic domain of the FUT2 as a probe, indicating that the three individuals were homozygous for a gene deletion in the FUT2. These results suggest that the T725G mutation of FUT1 and the gene deletion of FUT2 are responsible for the classical Indian Bombay phenotype.