Systematic sequence analysis of the human fucosyltransferase 2 (FUT2) gene identifies novel sequence variations and alleles

Association of fucosyltransferase 2 gene polymorphism with the susceptibility to norovirus infection in Han Chinese population

Fucosyltransferase 2 (FUT2) gene, which regulates the formation of Histoblood group antigens, could determine the human susceptibility to norovirus. This study aimed to investigate the correlation between FUT2 gene polymorphism and susceptibility to norovirus gastroenteritis in Han Chinese population. A total of 212 children patients with acute gastroenteritis were enrolled. The stool and serum samples were collected respectively. We used the qPCR method to detect the norovirus infection status from the stool samples, and we used serum samples to detect the FUT2 polymorphism. A case-control study was conducted to investigate the three common SNPs polymorphisms (rs281377, rs1047781, and rs601338) of FUT2 gene with sanger sequencing method. The results indicated that the homozygous genotypes and mutant allele of rs1047781 (A385T) would downgrade the risk of norovirus gastroenteritis in Chinese Han population (AA vs. TT, odds ratio [OR] = 0.098, 95% confidence interval [CI] = 0.026-0.370, p = 0.001; AA + AT vs. TT, OR = 0.118. 95% CI = 0.033-0.424, p = 0.001; A vs. T, OR = 0.528, 95% CI = 0.351-0.974, p = 0.002). There were no significant difference of rs281377 (C357T) and rs601338 (G428A) polymorphisms between norovirus positive and norovirus negative groups (p > 0.05). The haplotype T-T-G was less susceptible (OR = 0.49, 95% CI = 0.31-0.79, p = 0.0034) to norovirus infection compared to other haplotypes. Our results investigated the relationship between the FUT2 gene polymorphisms and norovirus susceptibility in Han Chinese population, and firstly revealed that children with homozygous genotypes and mutant alleles of FUT2 rs1047781 (A385T) were less susceptible to norovirus gastroenteritis.

A novel allele of FUT2 gene containing a deletion of nine bases (c.461_469delGGACCTTCT) in a Chinese Han blood donor

BACKGROUND AND OBJECTIVES

The FUT2 gene is responsible for the synthesis of the H antigen in body secretions. It is highly polymorphic and population specific. We investigated the FUT2 gene polymorphism in Chinese blood donors and found a novel deletion mutation in one non-secretor individual. This study aimed to identify mutation(s) responsible for a non-secretor phenotype.

MATERIALS AND METHODS

The Lewis blood group of a Chinese Han blood donor was typed using the standard serological technique and the FUT2 gene of the sample was analysed by Sanger sequencing. Clone sequencing was performed for determining the haplotype of the FUT2 gene. Bioinformatics tools were used for predicting the effect of the deletion on the FUT2 gene.

RESULTS

A novel nine-base deletion (c.461_469delGGACCTTCT) in the FUT2 gene was identified in a Chinese Han blood donor. Two haplotypes Se390,418 and se204,249,461_469del,772,993 were determined by clone sequencing. According to the prediction of bioinformatics tools, the mutation at c.461_469delGGACCTTCT might not influence the activity of the Se enzyme.

CONCLUSION

We identified a new FUT2 mutation, the deletion of nine bases (c.461_469delGGACCTTCT), in a Chinese Han blood donor. This deletion was reported for the first time.

The Human-Milk Oligosaccharide Profile of Lactating Women in Dhaka, Bangladesh

BACKGROUND

Human-milk oligosaccharides (HMOs) are an abundant component of human milk that have health-related effects on breastfeeding infants. Since variation in HMO composition can be explained by maternal and environmental factors, understanding the diversity in HMOs across settings and identifying context-specific factors associated with HMO abundances is important.

OBJECTIVES

The aim was to describe the HMO profile of Bangladeshi women and to estimate the effect of maternal vitamin D supplementation on HMO composition.

METHODS

In a cross-sectional analysis of data and samples from the Maternal Vitamin D for Infant Growth trial in Dhaka, Bangladesh (clinicaltrials.gov; NCT01924013), 192 participants were randomly selected including 96 from each of the placebo and highest-dose vitamin D supplementation groups. In mid-feed breast milk samples collected at a mean (±SD) postpartum age of 93 ± 7 d, absolute and relative abundances of 19 HMOs were analyzed by HPLC. "Secretors" were defined as participants with 2'fucosyllactose concentrations >350 nmol/mL. Associations between HMO concentrations and selected maternal or environmental factors were estimated by multivariable linear regression, adjusting for vitamin D group allocation and secretor status. HMO profiles of Bangladeshi women were compared with data from other international cohorts.

RESULTS

Overall, 34% (65/192) of participants were nonsecretors. Secretor status was associated with the concentrations of total HMOs and 79% (15/19) of individual HMOs. Vitamin D supplementation did not affect the total or individual concentration of any measured HMO. 3-Fucosyllactose concentration was significantly higher in breast milk samples collected in December to February compared with samples collected in March to May. HMO composition was similar to other previously reported cohorts.

CONCLUSIONS

The HMO profile of Bangladeshi women is predominantly determined by secretor status. Context-specific HMO data may improve understanding of the effects of HMOs on the infant microbiome and health and guide the development of HMO-containing interventions.

A one-year study of human milk oligosaccharide profiles in the milk of healthy UK mothers and their relationship to maternal FUT2 genotype

Human milk oligosaccharides (HMOs) are indigestible carbohydrates with prebiotic, pathogen decoy and immunomodulatory activities that are theorized to substantially impact infant health. The objective of this study was to monitor HMO concentrations over 1 year to develop a long-term longitudinal dataset. HMO concentrations in the breast milk of healthy lactating mothers of the Cambridge Baby Growth and Breastfeeding Study (CBGS-BF) were measured at birth, 2 weeks, 6 weeks, 3 months, 6 months and 12 months postpartum. HMO quantification was conducted by high-performance anion-exchange chromatography with pulsed amperometric detection using a newly validated "dilute-and-shoot" method. This technique minimizes sample losses and expedites throughput, making it particularly suitable for the analysis of large sample sets. Varying patterns of individual HMO concentrations were observed with changes in lactation timepoint and maternal secretor status, with the most prominent temporal changes occurring during the first 3 months. These data provide valuable information for the development of human milk banks in view of targeted distribution of donor milk based on infant age. Maternal FUT2 genotype was determined based on identification at single-nucleotide polymorphism rs516246 and compared with the genotype expected based on phenotypic markers in the HMO profile. Surprisingly, two mothers genotyped as secretors produced milk that displayed very low levels of 2'-fucosylated moieties. This unexpected discrepancy between genotype and phenotype suggests that differential enzyme expression may cause substantial variation in HMO profiles between genotypically similar mothers, and current genotypic methods of secretor status determination may require validation with HMO markers from milk analysis.

Two novel alleles on Fucosyltransferase 2 from northern Thai para-Bombay family and computational prediction on mutation effect

BACKGROUND

Major characteristics of the para-Bombay phenotype are the absence of ABH antigens on red blood cells due to fucosyltransferase 1 (FUT1) gene mutation and the presence of these antigens in body secretions due to the active fucosyltransferase 2 (FUT2) gene. An ABO blood group discrepancy can be identified via serological testing, and additional tests can be performed for confirmation. This study aimed to resolve the ABO discrepancy and report two novel alleles on the FUT2 gene in northern Thai para-Bombay families.

STUDY DESIGN AND METHODS

Twelve blood samples were collected from five suspected para-Bombay donors and their families. Nucleotide sequences of ABO, FUT1, and FUT2 were analyzed by polymerase chain reaction-sequence-based typing. Bioinformatics tools were used to predict the effect of suspected novel FUT2 alleles.

RESULTS

All samples exhibited normal ABO alleles, concordant with serological test results. FUT1 exhibited three known variants (c.328G>A, c.424C>T, and c.658C>T). Although FUT2 exhibited two known variants (c.357C>T and c.385A>T), two novel alleles were observed. One allele consisted of c.98A>G, c.101T>G, and c.357C>T with predicted normal transferase activity, whereas the other consisted of c.357C>T and c.617T>C with predicted abnormal enzyme activity.

DISCUSSION

Two novel alleles in FUT2 were reported among the affected para-Bombay individuals of northern Thai families. The c.617T>C variant caused an amino acid change from valine to alanine at position 206, predicted to be an inactive FUT2 enzyme. Inheritance of this variant with the recessive FUT1 allele may lead to inheritance of the rare Bombay blood group in the progeny.

Microbial Glycoside Hydrolases in the First Year of Life: An Analysis Review on Their Presence and Importance in Infant Gut

The first year of life is a crucial period during which the composition and functionality of the gut microbiota develop to stabilize and resemble that of adults. Throughout this process, the gut microbiota has been found to contribute to the maturation of the immune system, in gastrointestinal physiology, in cognitive advancement and in metabolic regulation. Breastfeeding, the “golden standard of infant nutrition,” is a cornerstone during this period, not only for its direct effect but also due to its indirect effect through the modulation of gut microbiota. Human milk is known to contain indigestible carbohydrates, termed human milk oligosaccharides (HMOs), that are utilized by intestinal microorganisms. Bacteria that degrade HMOs like Bifidobacterium longum subsp. infantis, Bifidobacterium bifidum, and Bifidobacterium breve dominate the infant gut microbiota during breastfeeding. A number of carbohydrate active enzymes have been found and identified in the infant gut, thus supporting the hypothesis that these bacteria are able to degrade HMOs. It is suggested that via resource-sharing and cross-feeding, the initial utilization of HMOs drives the interplay within the intestinal microbial communities. This is of pronounced importance since these communities promote healthy development and some of their species also persist in the adult microbiome. The emerging production and accessibility to metagenomic data make it increasingly possible to unravel the metabolic capacity of entire ecosystems. Such insights can increase understanding of how the gut microbiota in infants is assembled and makes it a possible target to support healthy growth. In this manuscript, we discuss the co-occurrence and function of carbohydrate active enzymes relevant to HMO utilization in the first year of life, based on publicly available metagenomic data. We compare the enzyme profiles of breastfed children throughout the first year of life to those of formula-fed infants.

ABO genotypes and the risk of esophageal and gastric cancers

BACKGROUND

Blood type has been associated with the risk of gastric cancer, but few studies have examined the association with esophageal squamous cell carcinoma (ESCC).

METHODS

We conducted a case-control study using genotyping data of Chinese individuals, including cases of 2022 ESCC, 1189 gastric cardia adenocarcinoma, 1161 gastric noncardia adenocarcinoma, and 2696 controls. Genetic blood type was imputed using three single nucleotide polymorphisms. We used logistic regression to examine the association between blood type and the risk of each cancer.

RESULTS

Compared to blood type O, the risk of ESCC was significantly elevated for blood type B and AB, with the highest risk for type AB (OR, 95%CI: 1.34, 1.07-1.67). Analysis of genotype suggested that the association of ESCC was from carrying the B allele. Similarly, blood type was significantly associated with gastric noncardia adenocarcinoma (P < 0.001) with risk significantly elevated in type A (1.37, 1.14-1.65) and AB (1.44, 1.10-1.89) compared to type O. Blood type was not associated with gastric cardia adenocarcinoma (P = 0.13).

CONCLUSIONS

This study provides novel insights into the association between blood type and the risk of ESCC and restricted previously observed association to only gastric noncardia cancer, providing important evidence to clarify the pattern of association and suggesting mechanisms of action.

Survey and characterization of nonfunctional alleles of FUT2 in a database

The expression of ABO antigens in human saliva is regulated by the FUT2 gene, which encodes a secretor type α(1,2)fucosyltransferase. Secretors express ABO substrates in saliva and non-secretors do not. Secretor status is an object of concern, especially for susceptibility to various infectious diseases. A multitude of single nucleotide polymorphisms (SNPs) and copy number variations (CNVs) have been reported, and they show unique distributions among different populations. In this study, we selected 18 uncharacterized FUT2 alleles listed in the Erythrogene database and obtained genomic DNA having these alleles. We experimentally confirmed the haplotypes, but 10 of 18 alleles disagreed with those in the database, which may be attributed to their low frequency. We then examined the activity of the encoded α(1,2)fucosyltransferase for 13 alleles by flow cytometry of H antigen expression. The impact of each nonsynonymous SNP on the enzyme was also estimated by software. We finally identified two non-secretor alleles (se610and se357,856,863) and one weak secretor allele (se262,357), while in silico analysis predicted that many alleles impair the function. The present results suggest that correct haplotyping and functional assays are desirable for analysis of the FUT2 gene.

Fucosylated Human Milk Oligosaccharides and N-Glycans in the Milk of Chinese Mothers Regulate the Gut Microbiome of Their Breast-Fed Infants during Different Lactation Stages

Human milk glycans provide a broad range of carbon sources for gut microbes in infants. Levels of protein glycosylation in human milk vary during lactation and may also be affected by the stages of gestation and lactation and by the secretor status of the mother. This was the first study to evaluate systematically dynamic changes in human milk oligosaccharides and fucosylated N-glycans in the milk of Chinese mothers with different secretor statuses during 6 months of lactation. Given the unique single nucleotide polymorphism site (rs1047781, A385T) on the fucosyltransferase 2 gene among Chinese populations, our report provides a specific insight into the milk glycobiome of Chinese mothers, which may exert effects on the gut microbiota of infants that differ from findings from other study cohorts.

The milk glycobiome has a significant impact on the gut microbiota of infants, which plays a pivotal role in health and development. Fucosylated human milk oligosaccharides (HMOs) and N-glycans on milk proteins are beneficial for the development of healthy gut microbiota, and the fucosylation levels of these glycans can be affected by the maternal fucosyltransferase 2 gene (FUT2). Here, we present results of longitudinal research on paired milk and stool samples from 56 Chinese mothers (CMs) and their breast-fed children. Changes of HMOs and fucosylated N-glycans in milk of CMs at different lactation stages were detected, which allowed characterization of the major differences in milk glycans and consequential effects on the gut microbiome of infants according to maternal FUT2 status. Significant differences in the abundance of total and fucosylated HMOs between secretor and nonsecretor CMs were noted, especially during early lactation. Despite a tendency toward decreasing milk protein concentrations, the fucosylation levels of milk N-glycans increased during late lactation. The changes in the levels of fucosylated HMOs and milk N-glycans were highly correlated with the growth of Bifidobacterium spp. and Lactobacillus spp. in the gut of infants during early and later lactation, respectively. Enriched expression of genes encoding glycoside hydrolases, glycosyl transferases, ATP-binding cassette (ABC) transporters, and permeases in infants fed by secretor CMs contributed to the promotion of these bacteria in infants. Our data highlight the important role of fucosylated milk glycans in shaping the gut microbiome of infants and provide a solid foundation for development of “personalized” nutrition for Chinese infants.

IMPORTANCE Human milk glycans provide a broad range of carbon sources for gut microbes in infants. Levels of protein glycosylation in human milk vary during lactation and may also be affected by the stages of gestation and lactation and by the secretor status of the mother. This was the first study to evaluate systematically dynamic changes in human milk oligosaccharides and fucosylated N-glycans in the milk of Chinese mothers with different secretor statuses during 6 months of lactation. Given the unique single nucleotide polymorphism site (rs1047781, A385T) on the fucosyltransferase 2 gene among Chinese populations, our report provides a specific insight into the milk glycobiome of Chinese mothers, which may exert effects on the gut microbiota of infants that differ from findings from other study cohorts.

An update on vitamin B12-related gene polymorphisms and B12 status

Background

Vitamin B12 is an essential micronutrient in humans needed for health maintenance. Deficiency of vitamin B12 has been linked to dietary, environmental and genetic factors. Evidence for the genetic basis of vitamin B12 status is poorly understood. However, advancements in genomic techniques have increased the knowledge-base of the genetics of vitamin B12 status. Based on the candidate gene and genome-wide association (GWA) studies, associations between genetic loci in several genes involved in vitamin B12 metabolism have been identified.

Objective

The objective of this literature review was to identify and discuss reports of associations between single-nucleotide polymorphisms (SNPs) in vitamin B12 pathway genes and their influence on the circulating levels of vitamin B12.

Methods

Relevant articles were obtained through a literature search on PubMed through to May 2017. An article was included if it examined an association of a SNP with serum or plasma vitamin B12 concentration. Beta coefficients and odds ratios were used to describe the strength of an association, and a P < 0.05 was considered as statistically significant. Two reviewers independently evaluated the eligibility for the inclusion criteria and extracted the data.

Results

From 23 studies which fulfilled the selection criteria, 16 studies identified SNPs that showed statistically significant associations with vitamin B12 concentrations. Fifty-nine vitamin B12-related gene polymorphisms associated with vitamin B12 status were identified in total, from the following populations: African American, Brazilian, Canadian, Chinese, Danish, English, European ancestry, Icelandic, Indian, Italian, Latino, Northern Irish, Portuguese and residents of the USA.

Conclusion

Overall, the data analyzed suggests that ethnic-specific associations are involved in the genetic determination of vitamin B12 concentrations. However, despite recent success in genetic studies, the majority of identified genes that could explain variation in vitamin B12 concentrations were from Caucasian populations. Further research utilizing larger sample sizes of non-Caucasian populations is necessary in order to better understand these ethnic-specific associations.

The FUT2 secretor variant p.Trp154Ter influences serum vitamin B12 concentration via holo-haptocorrin, but not holo-transcobalamin, and is associated with haptocorrin glycosylation

Vitamin B12 deficiency is common in older individuals. Circulating vitamin B12 concentration can be used to diagnose deficiency, but this test has substantial false positive and false negative rates. We conducted genome-wide association studies (GWAS) in which we resolved total serum vitamin B12 into the fractions bound to transcobalamin and haptocorrin: two carrier proteins with very different biological properties. We replicated reported associations between total circulating vitamin B12 concentrations and a common null variant in FUT2. This allele determines the secretor phenotype in which blood group antigens are found in non-blood body fluids. Vitamin B12 bound to haptocorrin (holoHC) remained highly associated with FUT2 rs601338 (p.Trp154Ter). Transcobalamin bound vitamin B12 (holoTC) was not influenced by this variant. HoloTC is the bioactive the form of the vitamin and is taken up by all tissues. In contrast, holoHC is only taken up by the liver. Using holoHC from individuals with known FUT2 genotypes, we demonstrated that FUT2 rs601338 genotype influences the glycosylation of haptocorrin. We then developed an experimental model demonstrating that holoHC is transported into cultured hepatic cells (HepG2) via the asialoglycoprotein receptor (ASGR). Our data challenge current published hypotheses on the influence of genetic variation on this clinically important measure and are consistent with a model in which FUT2 rs601338 influences holoHC by altering haptocorrin glycosylation, whereas B12 bound to non-glycosylated transcobalamin (i.e. holoTC) is not affected. Our findings explain some of the observed disparity between use of total B12 or holoTC as first-line clinical tests of vitamin B12 status.

Distribution of Lewis and Secretor polymorphisms and corresponding CA19-9 antigen expression in a Chinese population

The Lewis (FUT3) and Secretor (FUT2) genes, corresponding to secretion of Lewis ABO (H) histo‐blood group antigen CA19‐9, are highly polymorphic with differences between populations. In this study, the FUT3 and FUT2 genes in 316 Chinese participants were sequenced to detect polymorphisms, and the associated CA19‐9 antigen secretion was also measured. In total, 14 genotypes of FUT3 and 10 genotypes of FUT2 were verified. Le/Le, Le/le^59,508 and Le/le⁵⁹ were the main genotypes of FUT3 with frequencies of 53.2%, 10.7% and 3.5%, respectively. Se/Se, Se/se³⁸⁵ and se³⁸⁵/se³⁸⁵ were the main genotypes of FUT2, with frequencies of 21.4%, 18.6% and 16.2%, respectively. The alleles le¹⁰⁶⁷ and le⁵⁰⁸ were found extensively in the Chinese population, and the frequency of allele se³⁸⁵ was shown to be higher than previously reported. Phenotype analysis revealed that 9.8% of individuals were the Lewis‐negative type and 22.5% were the secretor‐negative type. Combined phenotypes showed that 3.2% of participants were of ‘double‐negative’ phenotype (le, se) and 19.3% were of single dominant non‐secretor phenotype (Le, se). Serum Lewis antigen CA19‐9 levels were significantly different between subgroups and consistent with the defined phenotype. Our study revealed the unique distribution of Lewis and Secretor polymorphisms in a large Chinese population, and decoded the combined genotypes of the two CA19‐9‐related genes.

Association of Fucosyltransferase 2 Gene Polymorphisms with Inflammatory Bowel Disease in Patients from Southeast China

Aims. Fucosyltransferase 2 (FUT2) gene potentially affects the constituent of intestinal microbiota, which play a crucial role in the pathogenesis of inflammatory bowel disease (IBD). This study investigated the association of FUT2 gene polymorphisms with IBD in southeast China. Methods. We collected 671 IBD patients and 502 healthy controls. FUT2 gene polymorphisms (C357T, A385T, and G428A) were determined by SNaPshot. Frequencies of the FUT2 genotypes, alleles, and haplotype between groups were compared by χ² test. Results. The allele and genotype frequencies of FUT2 did not differ between ulcerative colitis patients and controls (all P > 0.05). However, mutant allele and genotype of FUT2 (A385T) were significantly increased in Crohn's disease (CD) patients (P = 0.024, OR = 1.271, and 95% CI = 1.031–1.565; P < 0.001, OR = 1.927, and 95% CI = 1.353–2.747, resp.). The same conclusion was drawn from FUT2 (G428A) (P = 0.023, OR = 3.324, and 95% CI = 1.108–9.968; P = 0.044, OR = 1.116–10.137, and 95% CI = 1.116–10.137, resp.). The haplotype TT formed with “C357T and A385T” was more prevalent in CD patients than in controls (P = 0.020, OR = 1.277, and 95% CI = 1.036–1.573). Besides, frequencies of mutant allele and genotype of FUT2 (A385T) were significantly lower in patients with ileocolonic CD than in those with colonic CD (P = 0.001 and 0.002, resp.) and ileal CD (P = 0.007 and 0.004, resp.). Conclusions. FUT2 gene polymorphisms and haplotypes were associated with the susceptibility to CD but not UC.

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.

Optimize CA19-9 in detecting pancreatic cancer by Lewis and Secretor genotyping

BACKGROUND

Carbohydrate antigen 19-9 (CA19-9) is currently the most widely used biomarker for pancreatic cancer. It is well-known that Lewis and Secretor status can affect CA19-9 biosynthesis. This study was performed to optimize CA19-9 in detecting pancreatic cancer using Lewis and Secretor dependent cut-off values.

METHODS

Lewis and Secretor genotypes were determined by Sanger sequencing in a large cohort of subjects (578 cases with pancreatic cancer, 210 cases with benign pancreatic disease, 315 normal subjects). The effectiveness of CA19-9 for detecting pancreatic cancer using Lewis and Secretor group dependent cut-off values was evaluated.

RESULTS

The Lewis (-), Mixed, and Secretor (-) groups had low, medium, and high CA19-9 biosynthesis, respectively. In Lewis (-) pancreatic cancer (all stages), CA19-9 had a sensitivity of 48.6% and a specificity of 95.9% when 1.8 U/mL was used as the cut-off value. The sensitivity of CA19-9 in detecting all stages of pancreatic cancer improved from 80.1% to 88.0% and the negative predictive value increased from 81.2% to 87.1% without compromising other values when using group dependent cut-off values. The sensitivity of CA19-9 for the detection of stage I, II pancreatic cancer increased from 76.1% to 87.2%.

CONCLUSIONS

The value of CA19-9 in detecting pancreatic cancer was optimized by using group dependent cut-off values based on Lewis and Secretor genotypes. CA19-9 can be applied as an early detector of pancreatic cancer using group dependent cut-off values.

Association of Ulcerative Colitis with FUT2 and FUT3 Polymorphisms in Patients from Southeast China

OBJECTIVES

Dysbiosis of intestinal microbiota has been implicated in ulcerative colitis (UC). Fucosyltransferase (FUT) 2 and FUT3 determine expression of histo-blood group antigens in the gut and may affect the intestinal microbiota. We investigated the association between FUT2 and FUT3 polymorphisms and UC in Chinese patients.

METHODS

We genotyped FUT2 (rs281377, rs1047781 and rs601338) and FUT3 (rs28362459, rs3745635 and rs3894326) in 485 UC patients and 580 healthy controls using SNaPshot. We also evaluated expression of Lewis a and b antigens in the sigmoid colon of 7 UC patients and 7 patients with benign colonic polyps.

RESULTS

The frequencies of mutant allele (A) and genotype (GA+AA) in FUT3 (rs3745635) were higher in UC patients than controls (P = 0.016, 95%CI: 1.339-1.699; P = 0.038, 95%CI: 1.330-1.742, respectively). Stratified analyses revealed that the frequencies of mutant allele (G) and genotype (TG+GG) of FUT3 (rs28362459) were significantly lower in patients with extensive colitis than those with distal colitis (P<0.001, 95%CI: 0.503-0.742; P = 0.001, 95%CI: 0.567-0.786, respectively). Similar conclusions were drawn for the mutant allele (A) and genotype (GA+AA) of FUT3 (rs3745635) in patients with extensive colitis compared to those with distal colitis (P = 0.006, 95%CI: 0.553-0.845; P = 0.011, 95%CI: 0.621-0.900, respectively). Although expression of Lewis b antigen in the sigmoid colon did not differ between UC patients and controls, Lewis a antigen expression was higher in the cryptic epithelium of both inflammatory and non-inflammatory sigmoid colon of UC patients than controls (P = 0.028).

CONCLUSIONS

Our findings indicated that polymorphisms in FUT3 and its intestinal expression might be associated with UC pathogenesis.

Genomic analysis of para-Bombay individuals in south-eastern China: the possibility of linkage and disequilibrium between FUT1 and FUT2

BACKGROUND

The para-Bombay phenotype results from a variety of mutations in the α-(1,2)-fucosyltransferase gene (FUT1). We investigated samples from seven Chinese probands serologically typed as having the para-Bombay phenotype.

MATERIALS AND METHODS

The para-Bombay phenotype was identified by standard serological methods. Genetic mutations of FUT1 and FUT2 genes were analysed by DNA sequencing. Heterozygous mutations of FUT1 were identified by TOPO cloning sequencing. Blood samples from 331 randomly-selected Chinese donors were analysed with the SNaPshot system to distinguish five known mutations (Se C357T, A385T, G428A, G716A and FUT1 880delTT) in the FUT1 and FUT2 genes. The genetic characteristics of all para-Bombay probands identified in the Fujian Blood Centre, including those in the present study, were also summarised.

RESULTS

Three FUT1 genotypes, h1/h1 (5 individuals), h1/h6 (1 individual) and h3/h2 (1 individual), and three FUT2 genotypes, Se(357)/Se(357) (5 individuals), Se(357)/Se(357, 385) (1 individual) and Se(357)/Se(357, 716) (1 individual) were observed in seven para-Bombay probands. Among 331 donors, only one individual carried the G716A and 880delTT mutations in heterozygosity; this subjects FUT1 and FUT2 genotypes were H/h2 and Se(357)/Se(357, 716), respectively.

CONCLUSION

The review of all para-Bombay probands identified in the Fujian Blood Centre showed that h1 and h2 are the predominant non-functional FUT1 alleles in Fujian para-Bombay individuals. Our data confirm the hypothesis that the h2 allele is linked to Se(357, 716), and the concurrence of unique FUT1 and FUT2 mutations is geographically specific.

Blood Groups in Infection and Host Susceptibility

Blood group antigens represent polymorphic traits inherited among individuals and populations. At present, there are 34 recognized human blood groups and hundreds of individual blood group antigens and alleles. Differences in blood group antigen expression can increase or decrease host susceptibility to many infections. Blood groups can play a direct role in infection by serving as receptors and/or coreceptors for microorganisms, parasites, and viruses. In addition, many blood group antigens facilitate intracellular uptake, signal transduction, or adhesion through the organization of membrane microdomains. Several blood groups can modify the innate immune response to infection. Several distinct phenotypes associated with increased host resistance to malaria are overrepresented in populations living in areas where malaria is endemic, as a result of evolutionary pressures. Microorganisms can also stimulate antibodies against blood group antigens, including ABO, T, and Kell. Finally, there is a symbiotic relationship between blood group expression and maturation of the gastrointestinal microbiome.

Genetic susceptibility to norovirus GII.3 and GII.4 infections in Chinese pediatric diarrheal disease

BACKGROUND

Noroviruses (NoVs) are a leading cause of viral diarrhea in young children. Secretor status has been confirmed to be linked with Norwalk virus (NoV GI.1) infection but there is limited information about whether secretor genotypes are associated with pediatric NoV epidemic strains in vivo.

METHODS

In this study, fecal specimens and serum samples were collected from 124 hospitalized children with acute diarrhea in Xi'an, China. TaqMan real-time reverse transcription polymerase chain reaction was used to detect NoVs in fecal samples, and NoV-positive samples were further verified using conventional reverse transcription polymerase chain reaction and sequenced. DNA was extracted from sera and TaqMan single-nucleotide polymorphism genotyping assay was applied to determine the FUT2 A385T polymorphism.

RESULTS

Only NoV GII.3 and GII.4 genotypes were found in NoV-positive samples, and NoVs were detected in 25% (15/60), 40.5% (17/42) and 9.1% (2/22) of children with homozygous secretor genotype (Se 385 Se 385), heterozygous secretor genotype (Se 385 se 385) and homozygous weak secretor genotype (se 385 se 385), respectively. Children with secretor genotypes Se 385 Se 385 and Se 385 se 385 were significantly (P < 0.05) more susceptible to combined NoV GII.3 and GII.4 infections than children with weak secretor genotype se 385 se 385.

CONCLUSIONS

These findings indicate that secretor positivity is significantly associated with GII.3 and GII.4 infections in Chinese pediatric diarrheal disease and the weak secretor phenotype does not completely protect children from GII.3 and GII.4 infections.

Associations of FUT2 and FUT3 gene polymorphisms with Crohn's disease in Chinese patients

BACKGROUND AND AIM

FUT2 and FUT3 genes are responsible for the formation of histo-blood group antigens, which act as binding sites for some intestinal microbes. Several studies suggested that FUT2 gene might affect the intestinal microbiota composition and modulate innate immune responses. However, the effect of FUT2 polymorphisms on Crohn's disease (CD) is uncertain. Our study aimed to analyze associations of CD with FUT2 and FUT3 polymorphisms in Chinese population.

METHODS

A total of 273 CD patients and 479 controls were recruited. The genotypes of FUT2 (rs281377, rs1047781, and rs601338) and FUT3 (rs28362459, rs3745635, and rs3894326) were detected by SNaPshot analysis.

RESULTS

Compared with controls, homozygote TT of FUT2 (rs1047781) was significantly increased in CD patients (TT vs others; P = 0.002, odds ratio [OR] = 1.767, 95% confidence interval [CI] = 1.235-2.528). The haplotype TT formed with FUT2 (rs281377) and (rs1047781) was more prevalent in CD patients than in controls (48.9% vs 43.5%, P = 0.046). Mutant T allele and homozygote TT of FUT2 (rs1047781) were increased in colonic CD patients compared with controls (P < 0.001, OR = 1.843, 95% CI = 1.353-2.512; P < 0.001, OR = 2.607, 95% CI = 1.622-4.191, respectively). Although allele and genotypic distributions of FUT3 were not statistically different between CD patients and controls, mutant allele and genotype of FUT3 (rs28362459) and (rs3745635) were significantly discrepant in three subgroups of CD patients according to lesion locations (all P < 0.05).

CONCLUSIONS

Our study strongly implicates the polymorphic locus of FUT2 (rs1047781) in CD susceptibility in Chinese population. Mutations of FUT3 (rs28362459) and (rs3745635) might influence the lesion locations in CD patients.

The summary of FUT1 and FUT2 genotyping analysis in Chinese para-Bombay individuals including additional nine probands from Guangzhou in China

BACKGROUND

The para-Bombay phenotype is characterized by the absence or weak expression of ABH antigens on the surface of red blood cells, but normal expression in saliva.

STUDY DESIGN AND METHODS

The para-Bombay phenotype of the nine Chinese probands was identified by standard serologic techniques. The coding regions of FUT1 and FUT2 genes were amplified by polymerase chain reaction and then directly sequenced. ABO genotyping was performed by polymerase chain reaction with sequence-specific priming method. The FUT1 and FUT2 genotypes and the distribution in all reported Chinese para-Bombay individuals including our study were also summarized.

RESULTS

Five FUT1 genotypes, h1h3 (n = 3), h1h2 (n = 3), h1h1 (n = 1), h3h3 (n = 1), and h2h3 (n = 1), and three functional FUT2 genotypes, Se(357) Se(357) (n = 4), Se(357) Se(357, 716) (n = 4), and Se(357) Se(357, 385) (n = 1) described before were identified in nine probands.

CONCLUSIONS

The review of the literature shows that a total of 17 FUT1 alleles and four FUT2 alleles (Se(357), Se(357,716), Se(357 385), Se) have been identified in Chinese para-Bombay individuals. The four FUT1 alleles, h1 (547delAG), h2 (880delTT), h3 (C658T), and h4 (C35T; A980C) are most prevalent, which account for more than 90% of all allele counts and are essential to be involved when developing para-Bombay genotyping kit for Chinese.

Association of fucosyltransferase 2 gene variants with ulcerative colitis in Han and Uyghur patients in China

AIM

To investigate the contribution of fucosyltransferase 2 (FUT2) variants to the genetic susceptibility and clinical heterogeneity of ulcerative colitis (UC) between Han and Uyghur patients in Xinjiang, China.

METHODS

A total of 102 UC patients (53 Han patients including 22 men and 31 women, and 49 Uyghur patients including 25 men and 24 women; aged 48 ± 16 years) and 310 age- and sex-matched healthy controls were enrolled from January 2010 to May 2011 in Xinjiang People's Hospital of China. UC was diagnosed based on the clinical, endoscopic and histological findings following Lennard-Jones criteria. Blood samples were collected and genomic DNA was extracted by the routine laboratory methods. Polymerase chain reaction-sequence-based typing method was used to identify FUT2 variants rs281377, rs1047781, rs601338 and rs602662. Genotypic and allelic frequencies were documented and compared between the UC patients and the healthy controls. Genotypic frequencies were also compared between Han and Uyghur patients. Potential association of genetic variation and UC between Han and Uyghur patients was examined.

RESULTS

rs281377 was found significantly associated with UC in the Han population as compared with the controls (P = 0.011) while rs281377 was not associated with UC in the Uyghur population (P = 0.06). TT homozygous rs281377 frequencies were higher in the UC groups than in the controls (88.7% vs 68.7% and 55.1% vs 50.3%). rs1047781 was specifically associated with UC in the Uyghur population (P = 0.001), but not associated with UC in the Han population (P = 0.13). TT homozygous rs1047781 frequencies were lower in the UC groups than in the controls (9.5% vs 11.8% and 4.0% vs 6.7%). rs601338 was statistically related to UC in both populations (Han, P = 0.025; Uyghur, P = 8.33 × 10(-5)). AA homozygous rs601338 frequencies were lower in the UC groups than in the controls (0% vs 1.8% and 12.2% vs 13.4%). No association was found between rs602662 and UC in both Han and the Uyghur populations. Allelic analysis showed that rs281377 allele was significantly associated with UC in the Han population as compared with the controls [P = 0.001, odd ratio (OR) = 0.26], however, it was not associated with UC in the Uyghur population (P = 0.603, OR = 1.14), and rs1047781 allele was associated with UC in the Uyghur population (P = 0.001, OR = 0.029) while it was not associated with UC in the Han population (P = 0.074, OR = 0.62). Moreover, rs601338 was associated with UC in both Han (P = 0.005, OR = 0.1) and Uyghur populations (P = 0.002, OR = 0.43). Meta analysis showed that rs1047781 and rs601338 conferred risk of UC as compared with the controls [P = 0.005, OR = 0.47; P = 0.0003, OR = 0.35; 95% confidence interval (CI) = 0.31-0.72 and 0.21-0.58], but rs281377 and rs602662 showed no statistically significant differences between patients with UC and controls (P = 0.10, OR = 0.71; P = 0.68, OR = 0.09; 95% CI = 0.47-1.07 and 0.56-1.47).

CONCLUSION

Functionally relevant FUT2 gene variants are associated with UC, suggesting that they play a potential role in the pathogenesis of UC and may contribute to the clinical heterogeneity of UC between Han and Uyghur patients.

Identification of 14 new alleles at the fucosyltransferase 1, 2, and 3 loci in Styrian blood donors, Austria

BACKGROUND

Genes for fucosyltransferases 1 (FUT1:H), 2 (FUT2:Secretor), and 3 (FUT3:Lewis) encode enzymes crucial for ABH and Lewis blood group antigen synthesis. They are highly polymorphic and ethnically and geographically specific.

STUDY DESIGN AND METHODS

Genetic variations and allele frequencies of FUT1, FUT2, and FUT3 encoding regions and flanking sequences were analyzed in 100 Styrian blood donors by systematic sequencing. Haplotypes were verified with sequence-specific primers. To identify discrepancies, serologically determined ABO and Lewis blood groups were correlated to respective genotypes.

RESULTS

Two novel FUT1 alleles were defined by 9C>T (silent) and 991C>A (P331T) mutations, the latter located in the catalytic domain of the enzyme. Five new alleles of FUT2 were found: three were characterized by new variants and two resulted from new combinations of known polymorphisms. The new 412G>A (G138S) mutation also is located in the catalytic domain. A new nonsecretor allele, based on the presence of 428G>A (nonsense), was found. Another FUT2 allele may have resulted from an intragenic crossover event. FUT3 analysis revealed seven novel alleles, partly based on the new mutations 41G>A (R14H), 1060C>G (R354G), 735G>C (silent), and 882C>T (silent). While 41G>A is placed in the cytoplasmic domain and functional, 1060C>G is placed in the catalytic domain.

CONCLUSION

Multiple common and sporadic sequence variations including 14 new alleles at FUT1, FUT2, and FUT3 loci were identified. Four novel mutations result in amino acid substitution in the protein. Three of them are predicted to have adverse effects on the enzyme activity. A novel nonsecretor allele was found.

Genetic variation of FUT2 in Ovambos, Turks, and Mongolians

BACKGROUND

Many single-nucleotide polymorphisms (SNPs) have been identified in the coding region of the FUT2 locus, which encodes secretor type alpha(1,2)fucosyltransferase. These SNPs are highly population-specific.

STUDY DESIGN AND METHODS

The 1121-bp polymerase chain reaction (PCR) product containing the whole FUT2 coding region in three human populations, Ovambos (n = 74), Turks (n = 70), and Mongolians (n = 118), was sequenced. The haplotypes consisting of novel SNPs were determined by sequencing cloned inserts, and the haplotypes consisting of already reported SNPs were inferred by free computer software (PHASE). The functional significance of novel SNPs by transient expression study was also examined.

RESULTS

Twenty-four SNPs were found including seven novel SNPs (i.e., 4G > A, 244G > A, 442C > A, 489G > A, 569G > A, 665G > A, and 950C > T). A transient expression study suggested that the 244G > A, 569G > A, and 950C > T SNPs are enzyme-inactivating mutations.

CONCLUSION

This study identified 24 SNPs in the FUT2 gene, of which 7 were novel. The frequencies of alleles and genotypes were determined in Ovambos, Turks, and Mongolians. The allelic composition of each population was similar to those of geographically closer populations.