During the 15th International Histocompatibility and Immunogenetics Workshop (IHIWS), 14 human leukocyte antigen (HLA) laboratories participated in the Analysis of HLA Population Data (AHPD) project where 18 new population samples were analyzed statistically and compared with data available from previous workshops. To that aim, an original methodology was developed and used (i) to estimate frequencies by taking into account ambiguous genotypic data, (ii) to test for Hardy-Weinberg equilibrium (HWE) by using a nested likelihood ratio test involving a parameter accounting for HWE deviations, (iii) to test for selective neutrality by using a resampling algorithm, and (iv) to provide explicit graphical representations including allele frequencies and basic statistics for each series of data. A total of 66 data series (1-7 loci per population) were analyzed with this standard approach. Frequency estimates were compliant with HWE in all but one population of mixed stem cell donors. Neutrality testing confirmed the observation of heterozygote excess at all HLA loci, although a significant deviation was established in only a few cases. Population comparisons showed that HLA genetic patterns were mostly shaped by geographic and/or linguistic differentiations in Africa and Europe, but not in America where both genetic drift in isolated populations and gene flow in admixed populations led to a more complex genetic structure. Overall, a fruitful collaboration between HLA typing laboratories and population geneticists allowed finding useful solutions to the problem of estimating gene frequencies and testing basic population diversity statistics on highly complex HLA data (high numbers of alleles and ambiguities), with promising applications in either anthropological, epidemiological, or transplantation studies.

Background and Aims There is controversy as to whether the risk of relevant infection in IBD is related to immunosuppressants or the disease itself. The aims of this study were to evaluate: [1] the life-long prevalence and types of relevant infections in patients with IBD related to immunosuppressive treatment, and [2] the relationship of both infection and patient comorbidity to mortality. Methods Observational multicentre retrospective study of IBD patients that presented a relevant infection. For each case, four periods of infection exposure were analysed: P1: pre-IBD diagnosis, P2: from IBD diagnosis to immunosuppressant initiation, P3: during immunosuppressant therapy, and P4: after treatment withdrawal. Results The life-long prevalence of relevant infection in the total cohort of patients [6914] was 3%, and 5% in immunosuppressed patients [4202]. 366 relevant infections were found in 212 patients [P1: 9, P2: 17, P3: 334, and P4: 6]. Differences between periods were significant [p < 0.0001]. The most frequent types of infection were respiratory, intestinal and urinary. The most frequent opportunistic infections were tuberculosis [prevalence: 2.6/1000] and herpes zoster [prevalence: 3.9/1000]. Herpes zoster infection was associated with thiopurines alone or in combination with anti-TNF in 75% of the cases, whereas tuberculosis was associated with anti-TNF in 94% of patients. The overall mortality was 4.2%. Infection-related mortality was 2.8% and it was not influenced by comorbidity. Conclusions Relevant infections in IBD patients are rare and appear to be related to immunosuppression. Relevant infection is a major cause of death in IBD.

INTRODUCTION: To compare Engerix-B and Fendrix hepatitis B virus for primo vaccination in inflammatory bowel disease (IBD). METHODS: Patients with IBD were randomized 1:1 to receive Engerix-B double dose or Fendrix single dose at months 0, 1, 2, and 6. Anti-HBs titers were measured 2 months after the third and fourth doses. Response to vaccination was defined as anti-HBs ≥100 UI/L. Anti-HBs titers were measured 2 months after the third and fourth doses and again at 6 and 12 months after the fourth dose. RESULTS: A total of 173 patients were randomized (54% received Engerix-B and 46% Fendrix). Overall, 45% of patients responded (anti-HBs ≥100 IU/L) after 3 doses and 71% after the fourth dose. The response rate after the fourth dose was 75% with Fendrix vs 68% with Engerix-B (P = 0.3). Older age and treatment with steroids, immunomodulators, or anti–tumor necrosis factor were associated with a lower probability of response. However, the type of vaccine was not associated with the response. Anti-HBs titer negativization occurred in 13% of patients after 6 months and 20% after 12 months. Anti-HBs ≥100 IU/L after vaccination was the only factor associated with maintaining anti-HBs titers during follow-up. DISCUSSION: We could not demonstrate a higher response rate of Fendrix (single dose) over Engerix-B (double dose). A 4-dose schedule is more effective than a 3-dose regimen. Older age and treatment with immunomodulators or anti–tumor necrosis factors impaired the success. A high proportion of IBD patients with protective anti-HBs titers after vaccination loose them over time. The risk of losing protective anti-HBs titers is increased in patients achieving anti-HBs <100 IU/L after the vaccination.

Type 3 von Willebrand disease (VWD3) is a rare and severe bleeding disorder characterized by often undetectable von Willebrand factor (VWF) plasma levels, a recessive inheritance pattern, and heterogeneous genotype. The objective of this study was to identify the VWF defects in 265 European and Iranian patients with VWD3 enrolled in 3WINTERS-IPS (Type 3 Von Willebrand International Registries Inhibitor Prospective Study). All analyses were performed in centralized laboratories. The VWF genotype was studied in 231 patients with available DNA (121 [115 families] from Europe [EU], and 110 [91 families] from Iran [IR]). Among 206 unrelated patients, 134 were homozygous (EU/IR = 57/77) and 50 were compound heterozygous (EU/IR = 43/7) for VWF variants. In 22 patients, no or only one variant was found. A total of 154 different VWF variants (EU/IR = 101/58 [5 shared]) were identified among the 379 affected alleles (EU/IR = 210/169), of which 48 (EU/IR = 18/30) were novel. The variants p.Arg1659*, p.Arg1853*, p.Arg2535*, p.Cys275Ser, and delEx1_Ex5 were found in both European and Iranian VWD3 patients. Sixty variants were identified only in a single allele (EU/IR = 50/10), whereas 18 were recurrent (≥3 patients) within 144 affected alleles. Nine large deletions and one large insertion were found. Although most variants predicted null alleles, 21% of patients carried at least 1 missense variant. VWD3 genotype was more heterogeneous in the European population than in the Iranian population, with nearly twice as many different variants. A higher number of novel variants were found in the Iranian VWD3 patients.

Background Anti–tumor necrosis factor agents (anti-TNFs) are efficacious at preventing the postoperative recurrence (POR) of Crohn disease, as demonstrated in 2 randomized controlled trials. However, real-life data for infliximab or adalimumab in this setting are scarce. Our aim was to assess both the efficiency of anti-TNFs at preventing early POR of Crohn disease in clinical practice and the associated risk factors for POR. Methods Patients in whom anti-TNFs were prescribed for the prevention of POR within 3 months after ileocolonic resection and who had an endoscopic assessment within 18 months were identified from the ENEIDA registry. Clinical and endoscopic features were collected within 18 months after surgery. Results In total, 152 patients were included (55 treated with infliximab, 97 with adalimumab, and 39% with concomitant immunosuppressants). Anti-TNF treatment was started after a median time of 29 days (IQR 13–44) after surgery. Eighty-two percent of patients had at least one risk factor for POR, and 82% had been exposed to anti-TNFs before the index surgery. Overall, 34% had endoscopic POR (as defined using a Rutgeerts endoscopic score > i1); 14% had advanced endoscopic POR (>i2); and 20% had clinical POR, with no differences between infliximab and adalimumab. In the multivariate analysis, only perianal disease (odds ratio 2.73, 95% confidence interval [CI] 1.26–5.91) and rectal involvement (odds ratio 2.79, 95% CI 1.09–7.14) were independent predictors of endoscopic POR. Conclusions In clinical practice, anti-TNFs for the prevention of POR of Crohn disease are frequently used in patients experienced with anti-TNFs and with concomitant immunosuppressants. The efficacy of infliximab and adalimumab for POR prevention is similar and in accordance with the results obtained in randomized controlled trials.

In this study we investigated the human leucocyte antigen-A (HLA-A), -B and DRB1 polymorphism of Native American population of Paraguay, the Guarani Indians. We found that the HLA variability consisted of 5 HLA-A, 7 HLA-B and 6 HLA-DRB1 groups of alleles and of several specific alleles (B*1504, B*3505, B*3912, B*4004, B*5104, DRB1*0411, DRB1*1413) common in other Native American populations. The comparison of the HLA polymorphism of the Guaranis from Paraguay with the «Mestizos» of Paraguay and the Spaniards showed that the «Mestizos» of Paraguay are genetically very distant from the Guarani Indians of Paraguay but much more close to the Spaniards. This can be explained, at least in part, by the history of the country. Our results are of importance in transplantation, in particular in the search for an unrelated donor for a Paraguayan patient requiring hematopoietic stem cell transplantation.

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Introduction: Current guidelines recommend prophylactic treatment of hemophilia B with the missing coagulation factor IX, either with standard half-life or extended half-life products. Extended half-life products have half-lives three to six times longer than the former, allowing a reduction in the number of weekly injections and therefore, potentially impacting on treatment adherence and quality of life. Albutrepenonacog alfa is an extended half-life fusion protein of coagulation factor IX with recombinant human albumin, indicated for both on-demand and prophylactic treatment for bleeding in patients with hemophilia B of all ages. Areas covered: The authors review the clinical and pharmacokinetic characteristics of albutrepenonacog alfa, as well as the available information regarding trough levels and real-world evidence. Given the availability of other factor IX products in the market, indirect comparisons of clinical and pharmacokinetic characteristics are presented. Expert opinion: The authors exhibit their expert opinion on which patient profiles are candidates for prophylactic treatment with albutrepenonacog alfa, and on the management of patients in terms of dosing, regimens of administration and protocols for switching the treatment.