Kidd blood group system: outwardly simple with hidden complexity

The basics of the Kidd blood group system have been well described. Two of the three antigens, Jk^a and Jk^b, are polymorphic. The third, Jk3, is of very high prevalence in all populations except in individuals of Polynesian and Finnish extraction. Jk (a?b?) red cells do not express Jk3. The antigens are encoded by SLC14A1 gene on chromosome 18. JK*01 allele differs from JK*02 at nt 838 (G/A) and in the protein, at amino acid 280, Jk^a expression is associated with aspartate and asparagine is associated with Jk^b. The genetic background of the dominantly inherited In(Jk) Jk(a?b?) is due to an 84 bp deletion in ZFN850 on chromosome 19. Antibodies against all three antigens are clinically important. They can cause immediate haemolytic transfusion reactions and are a frequent cause of delayed transfusion reactions. Haemolytic disease of the foetus and newborn due to JK antibodies is generally much less severe than the response to incompatible transfusion. The JK protein on red cells functions as a urea transporter. Complexity in the system is due to the number of alternate alleles described. ISBT recognizes 24 alleles that silence Jk^a/Jk^b expression and 7 alleles causing weak or partial expression of Jk^a or Jk^b. These alleles can result in serological typing discrepancies, discordant serological/molecular results and production of an apparent Kidd alloantibody by an antigen‐positive individual. JK antigens may serve as minor histocompatibility antigens. The antibodies may play a role in renal graft survival when a JK‐incompatible donor kidney is transplanted.     

Sequence variation at the human ABO locus

The ABO blood group is the most important blood group system in transfusion medicine. Since the ABO gene was cloned and the molecular basis of the three major alleles delineated about 10 years ago, the gene has increasingly been examined by a variety of DNA‐based genotyping methods and analysed in detail by DNA sequencing. A few coherent observations emerge from these studies. First, there is extensive sequence heterogeneity underlying the major ABO alleles that produce normal blood groups A, B, AB and O when in correct combination with other alleles. Second, there is also extensive heterogeneity underlying the molecular basis of various alleles producing ABO subgroups such as A₂, A_x and B₃. There are over 70 ABO alleles reported to date and these alleles highlight the extensive sequence variation in the coding region of the gene. A unifying system of nomenclature is proposed to name these alleles. Third, extensive sequence variation is also found in the non‐coding region of the gene, including variation in minisatellite repeats in the 5′ untranslated region (UTR), 21 single nucleotide polymorphisms (SNPs) in intron 6 and one SNP in the 3′ UTR. The haplotypes of these variations reveal a specific relationship with the major ABO alleles. Fourth, excluding the common alleles, about half of the remaining alleles are due to new mutations and the other half can better be explained by intragenic recombination (both crossover and gene conversion) between common alleles. In particular, the recombination sites in hybrid alleles can be quite precisely defined through haplotype analysis of the SNPs in intron 6. This indicates that recombination is equally as important as point mutations in generating the genetic diversity of the ABO locus. Finally, a large number of ABO genotyping methods are available and are based on restriction analysis, allele specific amplification, mutation screening techniques or their combinations.     

Respiratory sinus arrhythmia and serotonin transporter promoter gene polymorphisms: Taking a triallelic approach makes a difference

It has been recently reported in Psychophysiology that carriers of the short allele of an insertion/deletion (ins/del) functional polymorphism in the promoter region (5‐HTTLPR) of the serotonin transporter gene may display decreased resting respiratory sinus arrhythmia (RSA). However, this region hosts another functionally connected single‐nucleotide polymorphism (rs25531), which should also be genotyped in order to correctly categorize the low‐ and high‐expressing alleles of 5‐HTTLPR. The present study investigated resting RSA in an ethnically homogenous sample (N = 143) of participants genotyped for both the ins/del and rs25531 polymorphisms in 5‐HTTLPR. In contrast with the biallelic genotypes, based only on the ins/del alleles, the triallelic 5‐HTTLPR genotypes (i.e., including rs25531) showed no association with resting RSA. Taking a triallelic approach to 5‐HTTLPR is thus necessary in order to avoid false positive results.     

Polymorphisms in the CLDN1 and CLDN7 genes are related to differentiation and tumor stage in colon carcinoma

Tight junction is composed of transmembrane proteins important for maintaining cell polarity and regulating ion flow. Among these proteins are the tissue‐specific claudins, proteins that have recently been suggested as tumor markers for several different types of cancer. An altered claudin expression has been observed in colon, prostatic, ovarian, and breast carcinoma. The aim of this study was to analyze the allele frequencies of three common single nucleotide polymorphisms (SNPs) in the genes for claudin 1 and claudin 7 in colon cancer (CC) patients and in a control population of healthy blood donors. Pyrosequencing was used to genotype the CLDN1 SNP rs9869263 (c.369C>T), and the CLDN7 SNPs rs4562 (c.590C>T) and rs374400 (c.606T>G) in DNA from 102 formalin fixed paraffin embedded (FFPE) colon cancer tissue, and 111 blood leukocyte DNA from blood/plasma donors. These results were correlated with clinical parameters such as TNM stage, tumor localization, tumor differentiation, complexity index, sex, and age. We found that there was a significant association between the CLDN1 genotype CC in tumor samples and a higher risk of colon cancer development (OR 3.0, p < 0.001). We also found that the CLDN7 rs4562 (c.590C>T) genotype CT had a higher risk of lymph node involvement (p = 0.031) and a lower degree of tumor differentiation (p = 0.028). In the control population, the allele frequencies were very similar to those in the HapMap cohort for CLDN7. The CLDN1 rs9869263 genotype (c.369C>T) was related to increased risk of colon cancer, and the CLDN7 rs4562 genotype (c.590C>T) was related to tumor differentiation and lymph node involvement in colon carcinoma. Further studies are warranted to ascertain their potential uses as biomarkers predicting tumor development, proliferation, and outcome in this disease.     

Cell‐free fetal DNA and fetal blood group genotyping: non‐invasive prenatal testing

In transfusion medicine and clinical immunology, cell‐free fetal DNA (cffDNA) is analysed from maternal plasma of pregnant women to predict fetal blood groups with the purpose of (1) assessing the risk of haemolytic disease of the fetus and newborn (HDFN) in immunized women and (2) guiding targeted Rh prophylaxis in non‐immunized RhD‐negative women. National programmes for guiding prophylaxis are now implemented in around 6–7 European countries; assay accuracy is very high, with sensitivities of 99·9%. Sensitivity is challenged by low quantities of cffDNA, especially in early pregnancy. Specificity is challenged by the polymorphic Rh blood group system, where careful attention is needed to navigate among the many RHD variants that may complicate cffDNA analysis and interpretation of results, especially in populations with mixed ethnicities. However, fetal RHD testing is feasible when implemented with careful attention to these issues. The success of predicting fetal RhD and its successful clinical implementation should encourage widespread implementation. For blood groups that are determined by SNPs, such as KEL or Rhc, novel techniques such as next‐generation sequencing and droplet digital PCR are now providing accurate non‐invasive prediction of these fetal blood groups. Future work on non‐invasive prenatal testing of fetal blood groups determined by SNPs may consolidate the application for cell‐free DNA testing for such targets. At ISBT, the newly formed cfDNA subgroup of the Red Cell Immunogenetics and Blood Group Terminology Working Party will work to facilitate clinical applications, implementation and evaluation of cell‐free DNA testing.     

Association of the HLA‐B27 antigen and the CTLA4 gene CT60/rs3087243 polymorphism with ankylosing spondylitis in Algerian population: A case–control study

Ankylosing spondylitis (AS) is a complex inflammatory disease that represents a major health problem both in Algeria and worldwide. Several lines of evidence support that genetic risk factors play a role in AS etiology and the CTLA4 gene has attracted a considerable attention. In this study, we were interested in evaluating the HLA‐B27 frequency and in exploring the CTLA4 gene in a sample of the North African population. The dataset of the current study is composed of 81 patients with AS and 123 healthy controls. All samples were genotyped by TaqMan^®allelic discrimination assay. The genetic risk of the HLA‐B27 specificity and the CTLA4/CT60 polymorphism were assessed by odds ratios (OR) with 95% confidence intervals (CI). High spondylitis risk was detected for HLA‐B27 allele (OR= 14.62, p = 10^?6) in addition to a significant association of the CT60*G allele (OR= 1.89, p = .002). After gender and age stratifications, the association of the CT60*G allele was still significant in females sample (OR= 2.10, p = .001) and when age up to 30 years (OR = 2.21, p = .008). Interestingly, the CT60*G allele revealed an increased spondylitis risk in the B27 negative group (OR= 2.81, p = .006). The present work showed in West Algerian population that the HLA‐B27 antigen and the variation in the CTLA4 3′UTR region played an important role in the ankylosing spondylitis susceptibility. The heterogeneity of this disease is deduced by genetic difference found between B27+ and B27? groups.     

A 15‐year‐long Southern blotting analysis of FMR1 to detect female carriers and for prenatal diagnosis of fragile X syndrome in Taiwan

Here, we review the results of Southern blotting analyses of the FMR1 gene performed in our reference laboratory in Taiwan over a 15‐year period. In total, 725 high‐risk women with a family history of fragile X syndrome (FXS) or idiopathic intellectual disability, 3911 low‐risk pregnant women without such family history, and prenatal diagnosis data for 32 foetuses from 24 carrier mothers were included. Only 2 carriers were in the low‐risk group, which indicated a prevalence of 1 of 1955 women (95% confidence interval: 1/7156‐1/539). A total of 100 carriers were found to be in the high‐risk group, thus revealing a significantly higher frequency than the low‐risk group (100/725 vs 2/3911, P<0.0001). Eight of the 14 foetuses that inherited the maternal mutant allele were verified to have a full mutation, with the smallest maternal pre‐mutation allele carrying 56 CGG repeats. The overall findings confirmed that the carrier prevalence among low‐risk women in Taiwan is significantly lower than that reported in western countries. Therefore, the most important step for preventing FXS in Taiwan would be to focus on high‐risk women by promoting general awareness of this disease and spreading knowledge regarding the benefits of carrier screening and prenatal testing.     

HLA class I allele lineages and haplotype frequencies in Arabs of the United Arab Emirates

The high degree of polymorphism of the HLA system provides suitable genetic markers to study the diversity and migration of different world populations and is beneficial for forensic identification, anthropology, transplantation and disease associations. Although the United Arab Emirates (UAE) population of about nine million people is heterogeneous, information is limited for the HLA class I allele and haplotype frequencies of the Bedouin ethnic group. We performed low‐resolution PCR‐SSP genotyping of three HLA class I loci at HLA‐A, ‐B and ‐C for 95 unrelated healthy Bedouins from the cities of Al Ain and Abu Dhabi in the UAE. A total of 54 HLA allele lineages were detected; the most frequent low‐resolution allele lineages at each HLA locus were A*02 (0.268), B*51 (0.163) and C*07 (0.216). The inferred estimates for the two most frequent HLA‐A and HLA‐B haplotypes were HLA‐A*02 ~ HLA‐B*50 (0.070) and HLA‐A*02 ~ HLA‐B*51 (0.051), and the most frequent 3‐locus haplotype was HLA‐A*02 ~ HLA‐B*50 ~ HLA‐C*06 (0.068). The HLA allele lineage frequencies of the UAE Arabs were compared to those previously reported for 70 other world populations, and a strong genetic similarity was detected between the UAE Arabs and the Saudi Arabians from the west with evidence of a limited gene flow between the UAE Arabs and Pakistani across the Gulf from the east, and the UAE Arabs and Omani from the south of the Gulf Peninsula.     

Gene variability and degree of expression of vaccine candidate factor H binding protein in clinical isolates of Neisseria meningitidis

The factor H binding protein (fHbp) is currently being evaluated in clinical trials as a vaccine candidate for a meningococcal group B vaccine. We have previously described the prevalence and sequence variation of fHbp (Jacobsson et al., 2009) and here we investigate the expression of the antigen. The present study includes isolates from carriers (n = 62) and patients with invasive Neisseria meningitidis infections (n = 146), of which 62 had a fatal outcome. Among the invasive isolates from patients with fatal and non‐fatal infections fHbp allele 1 was most common (42% and 29% respectively), but it was only identified in 3% of the carrier isolates, where allele 16 was most frequent (13%). The Fluorescence‐activated cell sorting analysis identified fHbp expression in all except seven isolates and further analysis by Western blot showed that five of these seven samples were indeed negative using a polyclonal anti‐fHbp serum. The negative isolates belonged to serogroup B fHbp allele 24, Y allele 104, and W‐135 allele 16 (all invasive). Two were non‐serogroupable carrier isolates (allele 21 and 101). An interesting finding is that isolates from invasive infections with fatal outcome had lower expression of fHbp or lower affinity for the fHbp antibody compared to isolates from non‐fatal invasive infections and carriers.     

Spectrum of mutations in cystinuria patients presenting with prenatal hyperechoic colon

Cystinuria is a heterogeneous, rare but important cause of inherited kidney stone disease due to mutations in 2 genes: SLC3A1 and SLC7A9. Antenatal hyperechoic colon (HEC) has been reported in some patients as a non‐pathological consequence of the intestinal transport defect. We report 83 patients affected by cystinuria: 44 presented prenatally with a HEC (HEC group) and 39 with a classical postnatal form (CC group). SLC3A1 and SLC7A9 were sequenced. All patients were fully genotyped, and the relationship between the genotype and clinical features was analyzed. We identified mutations in SLC3A1 in 80% of the HEC group and in only 49% of the CC group. The SLC3A1 p.Thr216Met mutation was found in 21% of the alleles in the HEC group but was never found in the CC group. Most of the mutations found in the HEC group were considered severe mutations in contrast with the CC group. Twenty‐five novel mutations were reported. This study shows a relationship between genotype and the clinical form of cystinuria, suggesting that only the patients with the most severe mutations presented with an HEC. These results emphasized the need for prenatal cystinuria screening using classical third‐trimester ultrasound scan and the early management of suspected newborns.     

Molecular polymorphism of O alleles in the Chinese Han population

The ABO blood group system is the most important in transfusion medicine. O blood group is common in Chinese Han people, but the distribution of various O alleles is unknown. Sequences of exon6 and exon7 of the O allele at the ABO gene locus were studied in 100 individuals of the O phenotype randomly selected from the Chinese Han population. Some samples, when required, were cloned and sequenced spanning exon6 and exon7. Eight O alleles were found in the Chinese population. Most have the 2 common O01 or O02 alleles. The allele frequency of ABO*O01 was 0.47, and that of ABO*O02 was 0.495. One individual was found to have O05 allele. Five alleles were found to differ from all alleles reported to date. Four of these alleles differed from either the O01 allele (1 out of 4) or O02 allele (3 out of 4) by 1 point mutation at A468G, G489A, T526C, or T1104G. The fifth allele differed from the O01 allele since it does not have nt261G deletion but has C467T mutation. This novel allele occurred in 2 individuals. O genetic analysis suggests that the O01 allele prevails, with O1v accounting for about 97% of these in the Chinese Han population. The O03 allele that has been shown to occur with a frequency of <5% in other populations was not detected. But the novel O allele without 261G deletion has been found in Chinese for the first time. Surely more O alleles will be found in the Chinese population.     

Frequency of HLA‐A alleles in the Syrian population genotyped by sequence‐based typing

HLA‐A molecules are highly polymorphic. Their accurate typing at a high‐resolution level is crucial for successful organ, bone marrow and cord blood transplantation. Furthermore, several HLA alleles have been involved in susceptibility to autoimmune diseases, allergies, cancers and inflammations. In order to determine common HLA‐A alleles in Syria and their frequencies, sequence‐based typing (SBT) was used to genotype HLA‐A alleles at high resolution (four digit level) among one hundred and thirty randomly selected Syrian individuals. Exons 2, 3 and 4 of the HLA‐A gene were amplified by PCR and sequenced. The sbt ‐engine software was used for allele assignment. Ambiguities were solved using group‐specific sequencing primers (GSSPs). We could identify 32 different HLA‐A alleles which were divided into 3 groups: high frequency (approximately 10%, A*01:01; A*24:02; A*03:01; A*02:01), moderate frequency (approximately 3%, such as A*02:05, A*31:01 and A*33:01), and low frequency (approximately 1%, such as A*02:11, A*29:01, A*02:02 and A*36:01). Homozygosity rate was higher than expected (11.5% vs. 7.15%). For high frequency alleles, our results show similarity to neighbouring countries. However, 15 alleles (such as A*02:04, A*02:06, A*02:11 and A*02:17) found in our cohort in low frequencies were never reported in some or all neighbouring countries. This is the first report on HLA‐A allele frequencies in Syria. In spite of the relatively low number of tested subjects, our results revealed a high degree of diversity, with 32 different alleles, reflecting the high ethnic heterogeneity of the Syrian population. The identification of alleles rarely or never reported in neighbouring countries indicates a higher genetic diversity in Syria.     

Refinement and delineation of the breakpoint regions of a chromosome 1;22 translocation in a patient with Costello syndrome*

Altered plasma levels of lipids and lipoproteins, obesity, hypertension, and diabetes are major risk factors for atherosclerotic cardiovascular disease. To identify genes that affect these traits and disorders, we looked for association between markers in candidate genes (apolipoprotein AII (apo AII), apolipoprotein AI‐CIII‐AIV gene cluster (apo AI‐CIII‐AIV), apolipoprotein E (apo E), cholesteryl ester transfer protein (CETP), cholesterol 7α‐hydroxylase (CYP7a), hepatic lipase (HL), and microsomal triglyceride transfer protein (MTP)) and known risk factors (triglycerides (Tg), total cholesterol (TC), apolipoprotein AI (apo AI), apolipoprotein AII (apo AII), apolipoprotein B (apo B), body mass index (BMI), blood pressure (BP), leptin, and fasting blood sugar (FBS) levels.) A total of 1,102 individuals from the Pacific island of Kosrae were genotyped for the following markers: Apo AII/MspI, Apo CIII/SstI, Apo AI/XmnI, Apo E/HhaI, CETP/TaqIB, CYP7a/BsaI, HL/DraI, and MTP/HhpI. After testing for population stratification, family‐based association analysis was carried out. Novel associations found were: 1) the apo AII/MspI with apo AI and BP levels, 2) the CYP7a/BsaI with apo AI and BMI levels. We also confirmed the following associations: 1) the apo AII/MspI with Tg level; 2) the apo CIII/SstI with Tg, TC, and apo B levels; 3) the Apo E/HhaI E2, E3, and E4 alleles with TC, apo AI, and apo B levels; and 4) the CETP/TaqIB with apo AI level. We further confirmed the connection between the apo AII gene and Tg level by a nonparametric linkage analysis. We therefore conclude that many of these candidate genes may play a significant role in susceptibility to heart disease. © 2002 Wiley‐Liss, Inc.     

Influence of NKG2C gene deletion and CCR5Δ32 in Pre‐eclampsia—Approaching the effect of innate immune gene variants in pregnancy

Pre‐eclampsia (PE) is a hypertensive disorder that affects an important number of pregnant women worldwide. The exact causes of PE remain poorly understood. However, inflammation and deregulation of innate immune cells, such as natural killer (NK) cells, contribute to PE pathogenesis. Besides, the mother's genetic background also impacts on PE susceptibility. Thus, genetic variants that potentially modify the behaviour of inflammatory cells may help us to understand the causes of PE. Variants of genes encoding NKG2C (expressed in NK cells) and C–C chemokine receptor type 5 (CCR5) (expressed mainly in leucocytes) are important targets in the study of gestational disorders. In this context, we evaluated the impact of both NKGC2 gene deletion and CCR5Δ32 gene variant on PE susceptibility in a population sample from central‐southeast Brazil composed by 369 women (156 with PE and 213 healthy pregnant women). No statistically significant association between the NKG2C gene deletion and susceptibility to PE was observed. However, taking into consideration the important role of NK cells in pregnancy, the influence of NKG2C gene deletion on PE pathogenesis should not be ruled out and deserves further studies in populations with different genetic/ethnic backgrounds. In addition, our results regarding CCR5Δ32 corroborate previous data from our group approaching a distinct cohort and reinforce CCR5Δ32 as a protective factor against PE development (p < 0.05).     

HLA class II allele polymorphism in an outbreak of chikungunya fever in Middle Andaman,India

A sudden upsurge of fever cases with joint pain was observed in the outpatient department, Community Health Centre, Rangat during July–August 2010 in Rangat Middle Andaman, India. The aetiological agent responsible for the outbreak was identified as chikungunya virus (CHIKV), by using RT‐PCR and IgM ELISA. The study investigated the association of polymorphisms in the human leucocyte antigen class II genes with susceptibility or protection against CHIKV. One hundred and one patients with clinical features suggestive of CHIKV infection and 104 healthy subjects were included in the study. DNA was extracted and typed for HLA‐DRB1 and DQB1 alleles. Based on the amino acid sequences of HLA‐DQB1 retrieved from the IMGT/HLA database, critical amino acid differences in the specific peptide‐binding pockets of HLA‐DQB1 molecules were investigated. The frequencies of HLA‐DRB1 alleles were not significantly different, whereas lower frequency of HLA‐DQB1*03:03 was observed in CHIKV patients compared with the control population [P = 0·001, corrected P = 0·024; odds ratio (OR)  = 0, 95% confidence interval (95% CI) 0·0–0·331; Peto's OR = 0·1317, 95% CI 0·0428–0·405). Significantly lower frequency of glutamic acid at position 86 of peptide‐binding pocket 1 coding HLA‐DQB1 genotypes was observed in CHIKV patients compared with healthy controls (P = 0·004, OR = 0·307, 95% CI 0·125–0·707). Computational binding predictions of CD4 epitopes of CHIKV by NetMHCII revealed that HLA‐DQ molecules are known to bind more CHIKV peptides than HLA‐DRB1 molecules. The results suggest that HLA‐DQB1 alleles and critical amino acid differences in the peptide‐binding pockets of HLA‐DQB1 alleles might have role in influencing infection and pathogenesis of CHIKV.     

Feeding biomechanics of Late Triassic metoposaurids (Amphibia: Temnospondyli): a 3D finite element analysis approach

The Late Triassic freshwater ecosystems were occupied by different tetrapod groups including large‐sized anamniotes, such as metoposaurids. Most members of this group of temnospondyls acquired gigantic sizes (up to 5 m long) with a nearly worldwide distribution. The paleoecology of metoposaurids is controversial; they have been historically considered passive, bottom‐dwelling animals, waiting for prey on the bottom of rivers and lakes, or they have been suggested to be active mid‐water feeders. The present study aims to expand upon the paleoecological interpretations of these animals using 3D finite element analyses (FEA). Skulls from two taxa, Metoposaurus krasiejowensis, a gigantic taxon from Europe, and Apachesaurus gregorii, a non‐gigantic taxon from North America, were analyzed under different biomechanical scenarios. Both 3D models of the skulls were scaled to allow comparisons between them and reveal that the general stress distribution pattern found in both taxa is clearly similar in all scenarios. In light of our results, both previous hypotheses about the paleoecology of these animals can be partly merged: metoposaurids probably were ambush and active predators, but not the top predators of these aquatic environments. The FEA results demonstrate that they were particularly efficient at bilateral biting, and together with their characteristically anteropositioned orbits, optimal for an ambush strategy. Nonetheless, the results also show that these animals were capable of lateral strikes of the head, suggesting active hunting of prey. Regarding the important skull size differences between the taxa analyzed, our results suggest that the size reduction in the North American taxon could be related to drastic environmental changes or the increase of competitors. The size reduction might have helped them expand into new ecological niches, but they likely remained fully aquatic, as are all other metoposaurids.     

Distribution of the <Emphasis Type="Italic">FYB</Emphasis><Superscript><Emphasis Type="Italic">ES</Emphasis></Superscript> and <Emphasis Type="Italic">RHCE*ce(733C>G)</Emphasis> alleles in an Argentinean population: Implications for transfusion medicine

Background  

The understanding of the molecular bases of blood groups makes possible the identification of red cell antigens and antibodies using molecular approaches, especially when haemagglutination is of limited value. The practical application of DNA typing requires the analysis of the polymorphism and allele distribution of the blood group genes under study since genetic variability was observed among different ethnic groups. Urban populations of Argentina are assumed to have a white Caucasian European genetic component. However, historical and biological data account for the influence of other ethnic groups. In this work we analyse FY and RH blood group alleles attributed to Africans and that could have clinical implications in the immune destruction of erythrocytes.     

Seroprevalence of antibodies to Borrelia burgdorferi sensu lato in healthy adults from western Norway: risk factors and methodological aspects

The aim of this study was to assess the seroprevalence of antibodies to Borrelia burgdorferi sensu lato in a healthy adult population from Sogn and Fjordane county in western Norway by different assays. Sera from 1213 blood donors at four different blood banks were analysed in Enzygnost Lyme link VlsE/IgG (IgG), Enzygnost Borreliosis IgM (IgM), and Immunetics C6 Lyme ELISA kit (C6). Sera showing positive or grey‐zone reactivities were further examined with Borrelia‐EUROLine‐RN‐AT IgG blot and Borrelia‐EUROLine‐RN‐AT IgM blot. The seroprevalences were 9.6%, 8.2%, 8.4%, 6.4% and 5.7%, respectively. The seroprevalence for IgG was lower in the eastern part of the county and in owners of pet animals. It was higher in men, and increased with age and number of tick bites. C6 and IgG gave comparable results. IgM only was found in 4.5%, more often in women, did not increase with age, and showed no relationship with geography, and 56.4% were positive in IgM blot. In conclusion, antibodies to B. burgdorferi s.l. are common in blood donors in western Norway. The results may be used for evaluation of predictive values of test results in patients, as well as a basis for test algorithms in the laboratory.     

Ancestral reconstruction and correlation of the frequencies of the hemoglobin S allele and the Duffy blood group alleles in human populations

Objectives : Malaria is an important selective force for human genetic adaptation due to the sustained, lethal impact it has had on populations worldwide. High frequencies of both hemoglobin S and the null allele FYB^ES of the Duffy blood group have been found in areas where this disease is endemic, attributed to the protective action of the carriers of these variants against malaria infection. The objective of this work was to perform ancestral reconstruction and analyze the correlation of the frequencies of these alleles throughout the phylogeny of 24 human populations. Methods : A tree topology and the allelic frequencies reported in the literature for the 24 populations were used. The ancestral frequencies for the two alleles were reconstructed using the maximum likelihood method and the Brownian model of evolution (CI = 95%), and the correlation analysis was performed using phylogenetically independent contrasts (PICs). Statistical analyses were performed with the statistical software R version 3.4.1. Results : For both alleles, a correspondence was found in the reconstruction of the ancestral frequencies, and a significant statistical correlation (p = .001) was observed between the S and FYB^ES alleles. Conclusions : These results provide evidence of an epistatic relationship between the two alleles, which may influence the fitness of the individuals who present with them when they are subjected to a selective force such as malaria.     

The susceptible HLA class II alleles and their presenting epitope(s) in Goodpasture's disease

Goodpasture's disease is closely associated with HLA, particularly DRB1*1501. Other susceptible or protective HLA alleles are not clearly elucidated. The presentation models of epitopes by susceptible HLA alleles are also unclear. We genotyped 140 Chinese patients and 599 controls for four‐digit HLA II genes, and extracted the encoding sequences from the IMGT/HLA database. T‐cell epitopes of α3(IV)NC1 were predicted and the structures of DR molecule‐peptide—T‐cell receptor were constructed. We confirmed DRB1*1501 (OR = 4·6, P = 5·7 × 10⁻²⁸) to be a risk allele for Goodpasture's disease. Arginine at position 13 (ARG13) (OR = 4·0, P = 1·0 × 10⁻¹⁷) and proline at position 11 (PRO11) (OR = 4·0, P = 2·0 × 10⁻¹⁷) on DRβ1, encoded by DRB1*1501, were associated with disease susceptibility. α_134–148 (HGWISLWKGFSFIMF) was predicted as a T‐cell epitope presented by DRB1*1501. Isoleucine₁₃₇, tryptophan₁₄₀, glycine₁₄₂, phenylalanine₁₄₃ and phenylalanine₁₄₅, were presented in peptide‐binding pockets 1, 4, 6, 7 and 9 of DR2b, respectively. ARG13 in pocket 4 interacts with tryptophan₁₄₀ and forms a hydrogen bond. In conclusion, we propose a mechanism for DRB1*1501 susceptibility for Goodpasture's disease through encoding ARG13 and PRO11 on MHC‐DRβ1 chain and presenting T‐cell epitope, α_134–148, with five critical residues.