Trans-ancestral fine-mapping of MHC reveals key amino acids associated with spontaneous clearance of hepatitis C in HLA-DQß1.

Spontaneous clearance of acute hepatitis C virus (HCV) infection is associated with single nucleotide polymorphisms (SNPs) on the MHC class II. We fine-mapped the MHC region in European (n = 1,600; 594 HCV clearance/1,006 HCV persistence) and African (n = 1,869; 340 HCV clearance/1,529 HCV persistence) ancestry individuals and evaluated HCV peptide binding affinity of classical alleles. In both populations, HLA-DQß1Leu26 (p valueMeta = 1.24 × 10-14) located in pocket 4 was negatively associated with HCV spontaneous clearance and HLA-DQß1Pro55 (p valueMeta = 8.23 × 10-11) located in the peptide binding region was positively associated, independently of HLA-DQß1Leu26. These two amino acids are not in linkage disequilibrium (r2 < 0.1) and explain the SNPs and classical allele associations represented by rs2647011, rs9274711, HLA-DQB1∗03:01, and HLA-DRB1∗01:01. Additionally, HCV persistence classical alleles tagged by HLA-DQß1Leu26 had fewer HCV binding epitopes and lower predicted binding affinities compared to clearance alleles (geometric mean of combined IC50 nM of persistence versus clearance; 2,321 nM versus 761.7 nM, p value = 1.35 × 10-38). In summary, MHC class II fine-mapping revealed key amino acids in HLA-DQß1 explaining allelic and SNP associations with HCV outcomes. This mechanistic advance in understanding of natural recovery and immunogenetics of HCV might set the stage for much needed enhancement and design of vaccine to promote spontaneous clearance of HCV infection.

Utilization of a surgical database to provide care and assess perioperative treatment and outcomes in patients with bleeding disorders.

OBJECTIVES: To describe the Indiana Hemophilia and Thrombosis Center (IHTC) surgical database, its key components, and exploratory analyses of surgeries conducted between 1998 and 2019. METHODS: Surgical data across bleeding disorders collected retrospectively (1998-2006) and prospectively (2006-2019) were analyzed. Perioperative hemostasis, complications, and surgical plan deviations were compared by bleeding disorder diagnosis and data collection period. RESULTS: Within the 21-year period, 3246 procedures were conducted in 1413 patients with a diagnosis of von Willebrand disease (vWD), hemophilia A (HA), hemophilia B (HB), and other bleeding disorders. Majority of the procedures were minor (63.3%), and median number of surgeries per patient was 1 (range: 1-22). Adequate perioperative hemostasis was achieved in 90.9%, complications occurred in 13.6%, and surgical plan deviations occurred in 31.3% of procedures. Inadequate perioperative hemostasis and surgical plan deviations occurred more frequently in procedures involving HB compared with other bleeding disorders. Complications were not significantly different across bleeding disorders (p = .164). The prospective data collection period was associated with higher rates of hemostatic efficacy (92.4% vs. 88.3%; p < .001), complications (14.3% vs. 12.3%; p < .001), and plan deviations (34.2% vs. 25.1%; p < .001). CONCLUSION: The surgical database is an important resource in surgical management in patients with bleeding disorders. Further evaluation will facilitate use for the development of predictive models and principles of care.

A Multiancestry Sex-Stratified Genome-Wide Association Study of Spontaneous Clearance of Hepatitis C Virus.

BACKGROUND: Spontaneous clearance of acute hepatitis C virus (HCV) infection is more common in women than in men, independent of known risk factors. METHODS: To identify sex-specific genetic loci, we studied 4423 HCV-infected individuals (2903 male, 1520 female) of European, African, and Hispanic ancestry. We performed autosomal, and X chromosome sex-stratified and combined association analyses in each ancestry group. RESULTS: A male-specific region near the adenosine diphosphate-ribosylation factor-like 5B (ARL5B) gene was identified. Individuals with the C allele of rs76398191 were about 30% more likely to have chronic HCV infection than individuals with the T allele (OR, 0.69; P = 1.98 × 10-07), and this was not seen in females. The ARL5B gene encodes an interferon-stimulated gene that inhibits immune response to double-stranded RNA viruses. We also identified suggestive associations near septin 6 and ribosomal protein L39 genes on the X chromosome. In box sexes, allele G of rs12852885 was associated with a 40% increase in HCV clearance compared with the A allele (OR, 1.4; P = 2.46 × 10-06). Septin 6 facilitates HCV replication via interaction with the HCV NS5b protein, and ribosomal protein L39 acts as an HCV core interactor. CONCLUSIONS: These novel gene associations support differential mechanisms of HCV clearance between the sexes and provide biological targets for treatment or vaccine development.

Multi-ancestry fine mapping of interferon lambda and the outcome of acute hepatitis C virus infection.

Clearance of acute infection with hepatitis C virus (HCV) is associated with the chr19q13.13 region containing the rs368234815 (TT/ΔG) polymorphism. We fine-mapped this region to detect possible causal variants that may contribute to HCV clearance. First, we performed sequencing of IFNL1-IFNL4 region in 64 individuals sampled according to rs368234815 genotype: TT/clearance (N = 16) and ΔG/persistent (N = 15) (genotype-outcome concordant) or TT/persistent (N = 19) and ΔG/clearance (N = 14) (discordant). 25 SNPs had a difference in counts of alternative allele >5 between clearance and persistence individuals. Then, we evaluated those markers in an association analysis of HCV clearance conditioning on rs368234815 in two groups of European (692 clearance/1 025 persistence) and African ancestry (320 clearance/1 515 persistence) individuals. 10/25 variants were associated (P < 0.05) in the conditioned analysis leaded by rs4803221 (P value = 4.9 × 10-04) and rs8099917 (P value = 5.5 × 10-04). In the European ancestry group, individuals with the haplotype rs368234815ΔG/rs4803221C were 1.7× more likely to clear than those with the rs368234815ΔG/rs4803221G haplotype (P value = 3.6 × 10-05). For another nearby SNP, the haplotype of rs368234815ΔG/rs8099917T was associated with HCV clearance compared to rs368234815ΔG/rs8099917G (OR: 1.6, P value = 1.8 × 10-04). We identified four possible causal variants: rs368234815, rs12982533, rs10612351 and rs4803221. Our results suggest a main signal of association represented by rs368234815, with contributions from rs4803221, and/or nearby SNPs including rs8099917.

Identifying the immune interactions underlying HLA class I disease associations.

Variation in the risk and severity of many autoimmune diseases, malignancies and infections is strongly associated with polymorphisms at the HLA class I loci. These genetic associations provide a powerful opportunity for understanding the etiology of human disease. HLA class I associations are often interpreted in the light of 'protective' or 'detrimental' CD8+ T cell responses which are restricted by the host HLA class I allotype. However, given the diverse receptors which are bound by HLA class I molecules, alternative interpretations are possible. As well as binding T cell receptors on CD8+ T cells, HLA class I molecules are important ligands for inhibitory and activating killer immunoglobulin-like receptors (KIRs) which are found on natural killer cells and some T cells; for the CD94:NKG2 family of receptors also expressed mainly by NK cells and for leukocyte immunoglobulin-like receptors (LILRs) on myeloid cells. The aim of this study is to develop an immunogenetic approach for identifying and quantifying the relative contribution of different receptor-ligand interactions to a given HLA class I disease association and then to use this approach to investigate the immune interactions underlying HLA class I disease associations in three viral infections: Human T cell Leukemia Virus type 1, Human Immunodeficiency Virus type 1 and Hepatitis C Virus as well as in the inflammatory condition Crohn's disease.

When considering someone's risk of disease, every person is different but some similarities can be found when looking across populations. Some people are more likely to develop a certain disease, while others are protected in some way. Part of this variation is explained by the individual's genes, while their lifestyle and environment are other factors. Numerous studies have looked for associations between different versions of genes, known as gene variants, and the occurrence of disease to identify who is at risk. There is one cluster of genes called the HLA genes that is a well-known hotspot for disease associations. The HLA cluster is named for the group of proteins it encodes, called the human leukocyte antigen (HLA) complex. These cell-surface proteins regulate the immune system in humans. These proteins are present on the surface of cells, and they help the immune system distinguish foreign invaders such as viruses and bacteria from the body's own cells. Variants in the HLA genes are associated with more than 100 diseases, including infectious diseases like HIV, autoimmune conditions such as multiple sclerosis, and some cancers. However, while identifying which genetic variants are associated with an increased or decreased risk of disease is relatively simple, understanding why those genetic variants are associated with a particular disease is much harder. Debebe et al. have developed a new method to find out why certain gene variants in the HLA cluster are associated with disease in humans. They used this method to investigate known genetic variants associated with three viral infections: HIV, hepatitis C, and human leukemia virus ­ and one inflammatory disease: Crohn's disease. Critically, Debebe et al. looked at the interactions between different immune cells and the cell-surface proteins encoded by the HLA gene variants in different cases of these diseases. In doing so, the analysis was able to identify which cells of the immune system were responsible for the associations between gene variants and diseases. In principle, this method could be applied to study any disease in any species. It could also be used in classic gene association studies to test for false positive results and "passenger" mutations, two common problems that beset sound interpretations from these studies.

Joint comorbidities among Swedish carriers of haemophilia: A register-based cohort study over 22 years.

BACKGROUND: A significant fraction of women with an impaired factor VIII or IX gene in the X chromosome, carriers of haemophilia, will have clotting factor activities corresponding to those seen in males with non-severe haemophilia, hence, experience an increased bleeding tendency. Data describing the long-term joint outcomes among carriers are limited. We compared the age at onset, frequency of joint-related diagnoses as well as joint surgery and related hospitalizations among carriers of haemophilia with sex- and birthdate-matched controls from the general population. METHODS: Carriers of haemophilia born 1941-2008 were identified through the haemophilia treatment centres' (HTCs) databases and the National Patient Register of Sweden. For each carrier, we included up to five individuals using the Swedish population register as comparisons. Data for the period 1987-2008 were obtained. RESULTS: Among 539 potential carriers identified, 213 had a known factor activity. Carriers with reduced factor activity and those with unknown factor activity had received their first joint-related diagnosis at a significantly earlier age than their comparisons. The same subgroups showed an overall 2.3- and 2.4-fold higher hazard for joint-related diagnoses compared with the general population. In addition, the hazards of joint-related outpatient hospitalization were 3.2-fold (95% CI: 1.2, 9.1) and 2.5-fold (95% CI: 1.6, 3.7). This was not observed for those with normal factor activity. CONCLUSION: Carriers of haemophilia suffer a significant risk for joint comorbidities. This risk seems to correlate to the factor activity. Our findings underline the importance of regular clinical follow-up of carriers at HTCs.

Multi-Ancestry Genome-Wide Association Study of Spontaneous Clearance of Hepatitis C Virus.

BACKGROUND & AIMS: Spontaneous clearance of hepatitis C virus (HCV) occurs in approximately 30% of infected persons and less often in populations of African ancestry. Variants in major histocompatibility complex (MHC) and in interferon lambda genes are associated with spontaneous HCV clearance, but there have been few studies of these variants in persons of African ancestry. We performed a dense multi-ancestry genome-wide association study of spontaneous clearance of HCV, focusing on individuals of African ancestry. METHODS: We performed genotype analyses of 4423 people from 3 ancestry groups: 2201 persons of African ancestry (445 with HCV clearance and 1756 with HCV persistence), 1739 persons of European ancestry (701 with HCV clearance and 1036 with HCV persistence), and 486 multi-ancestry Hispanic persons (173 with HCV clearance and 313 with HCV persistence). Samples were genotyped using Illumina (San Diego, CA) arrays and statistically imputed to the 1000 Genomes Project. For each ancestry group, the association of single-nucleotide polymorphisms with HCV clearance was tested by log-additive analysis, and then a meta-analysis was performed. RESULTS: In the meta-analysis, significant associations with HCV clearance were confirmed at the interferon lambda gene locus IFNL4-IFNL3 (19q13.2) (P = 5.99 × 10-50) and the MHC locus 6p21.32 (P = 1.15 × 10-21). We also associated HCV clearance with polymorphisms in the G-protein-coupled receptor 158 gene (GPR158) at 10p12.1 (P = 1.80 × 10-07). These 3 loci had independent, additive effects of HCV clearance, and account for 6.8% and 5.9% of the variance of HCV clearance in persons of European and African ancestry, respectively. Persons of African or European ancestry carrying all 6 variants were 24-fold and 11-fold, respectively, more likely to clear HCV infection compared with individuals carrying none or 1 of the clearance-associated variants. CONCLUSIONS: In a meta-analysis of data from 3 studies, we found variants in MHC genes, IFNL4-IFNL3, and GPR158 to increase odds of HCV clearance in patients of European and African ancestry. These findings could increase our understanding of immune response to and clearance of HCV infection.

Inhibitory killer cell immunoglobulin-like receptors strengthen CD8+ T cell-mediated control of HIV-1, HCV, and HTLV-1.

Killer cell immunoglobulin-like receptors (KIRs) are expressed predominantly on natural killer cells, where they play a key role in the regulation of innate immune responses. Recent studies show that inhibitory KIRs can also affect adaptive T cell-mediated immunity. In mice and in human T cells in vitro, inhibitory KIR ligation enhanced CD8+ T cell survival. To investigate the clinical relevance of these observations, we conducted an extensive immunogenetic analysis of multiple independent cohorts of HIV-1-, hepatitis C virus (HCV)-, and human T cell leukemia virus type 1 (HTLV-1)-infected individuals in conjunction with in vitro assays of T cell survival, analysis of ex vivo KIR expression, and mathematical modeling of host-virus dynamics. Our data suggest that functional engagement of inhibitory KIRs enhances the CD8+ T cell response against HIV-1, HCV, and HTLV-1 and is a significant determinant of clinical outcome in all three viral infections.

Fine-mapping of genetic loci driving spontaneous clearance of hepatitis C virus infection.

Approximately three quarters of acute hepatitis C (HCV) infections evolve to a chronic state, while one quarter are spontaneously cleared. Genetic predispositions strongly contribute to the development of chronicity. We have conducted a genome-wide association study to identify genomic variants underlying HCV spontaneous clearance using ImmunoChip in European and African ancestries. We confirmed two previously reported significant associations, in the IL28B/IFNL4 and the major histocompatibility complex (MHC) regions, with spontaneous clearance in the European population. We further fine-mapped the association in the MHC to a region of about 50 kilo base pairs, down from 1 mega base pairs in the previous study. Additional analyses suggested that the association in MHC is stronger in samples from North America than those from Europe.

The importance of genetic factors for the development of arthropathy: a longitudinal study of children and adolescents with haemophilia A.

Haemophilia A is a congenital bleeding disorder characterised by recurrent haemorrhages into the major joints. Haemophilic arthropathy is a well-established outcome of recurrent joint bleeding; however, it is clear that multiple factors determine the extent and severity of its occurrence. We sought to identify genetic factors related to abnormalities in range of motion (ROM) in the knees, ankles and elbows in a cohort of children and adolescents with haemophilia A not treated primarily with regular prophylaxis. Using data from the Haemophilia Growth and Development Study, we examined associations between 13,342 genetic markers and ROM scores measured at six-month intervals for up to seven years. As a first step, ordered logistic regression models were fit for each joint separately. A subset of SNP markers showing significant effects (p<0.01) on the right and left sides for at least two joints were included in a full model fit using a multivariate generalised linear mixed model assuming an ordinal response. The models contained all ROM scores obtained at all visits. Twenty-five markers analysed in the full model showed either increased or decreased risk of ROM abnormalities at the p<0.001 level. Several genes identified at either the first or second stage of the analysis have been associated with arthritis in a variety of large studies. Our results support the likelihood that risk for haemophilic arthropathy is associated with genetic factors, the identification of which holds promise for further advancing the individualisation of treatment.

Genome-wide association study of spontaneous resolution of hepatitis C virus infection: data from multiple cohorts.

UNLABELLED: Chinese translation BACKGROUND: Hepatitis C virus (HCV) infections occur worldwide and either spontaneously resolve or persist and markedly increase the person's lifetime risk for cirrhosis and hepatocellular carcinoma. Although HCV persistence occurs more often in persons of African ancestry and persons with genetic variants near interleukin-28B (IL-28B), the genetic basis is not well-understood. OBJECTIVE: To evaluate the host genetic basis for spontaneous resolution of HCV infection. DESIGN: 2-stage, genome-wide association study. SETTING: 13 international multicenter study sites. PATIENTS: 919 persons with serum HCV antibodies but no HCV RNA (spontaneous resolution) and 1482 persons with serum HCV antibodies and HCV RNA (persistence). MEASUREMENTS: Frequencies of 792 721 single nucleotide polymorphisms (SNPs). RESULTS: Differences in allele frequencies between persons with spontaneous resolution and persistence were identified on chromosomes 19q13.13 and 6p21.32. On chromosome 19, allele frequency differences localized near IL-28B and included rs12979860 (overall per-allele OR, 0.45; P = 2.17 × 10-30) and 10 additional SNPs spanning 55 000 base pairs. On chromosome 6, allele frequency differences localized near genes for HLA class II and included rs4273729 (overall per-allele OR, 0.59; P = 1.71 × 10-16) near DQB1*03:01 and an additional 116 SNPs spanning 1 090 000 base pairs. The associations in chromosomes 19 and 6 were independent and additive and explain an estimated 14.9% (95% CI, 8.5% to 22.6%) and 15.8% (CI, 4.4% to 31.0%) of the variation in HCV resolution in persons of European and African ancestry, respectively. Replication of the chromosome 6 SNP, rs4272729, in an additional 745 persons confirmed the findings (P = 0.015). LIMITATION: Epigenetic effects were not studied. CONCLUSION: IL-28B and HLA class II are independently associated with spontaneous resolution of HCV infection, and SNPs marking IL-28B and DQB1*03:01 may explain approximately 15% of spontaneous resolution of HCV infection.

The polygenic nature of inhibitors in hemophilia A: results from the Hemophilia Inhibitor Genetics Study (HIGS) Combined Cohort.

Studies of determinants of development of inhibitory Abs to factor VIII in people with hemophilia A indicate a complex process involving multiple factors. The Hemophilia Inhibitor Genetics Study (HIGS) Combined Cohort was formed to extend our understanding of the genetic background of risk. The study group contains 833 subjects from 3 independent cohorts: brother pairs and singletons with and without a history of inhibitors, as well as 104 brother pairs discordant for inhibitor status. Using an Illumina iSelect platform, 13 331 single-nucleotide polymorphisms from 1081 genes, primarily immune response and immune modifier genes, were typed. Each cohort was analyzed separately with results combined using a meta-analytic technique. After adjustment for potential confounders, 53 single-nucleotide polymorphisms were found to be significant predictors of inhibitor status using the criteria of odds ratios in the same direction in all cohorts or allowing for a 20% interval around an odds ratio = 1 in 1 of the 3 and significant in at least 2. Of the 53 markers, 13 had meta P < .001. Eight of the 53 were significant predictors among the discordant pairs. Results support the complexity of the immune response and encourage further research with the goal of understanding the pathways involved.

KIR2DL2 enhances protective and detrimental HLA class I-mediated immunity in chronic viral infection.

Killer cell immunoglobulin-like receptors (KIRs) influence both innate and adaptive immunity. But while the role of KIRs in NK-mediated innate immunity is well-documented, the impact of KIRs on the T cell response in human disease is not known. Here we test the hypothesis that an individual's KIR genotype affects the efficiency of their HLA class I-mediated antiviral immune response and the outcome of viral infection. We show that, in two unrelated viral infections, hepatitis C virus and human T lymphotropic virus type 1, possession of the KIR2DL2 gene enhanced both protective and detrimental HLA class I-restricted anti-viral immunity. These results reveal a novel role for inhibitory KIRs. We conclude that inhibitory KIRs, in synergy with T cells, are a major determinant of the outcome of persistent viral infection.

Genetic variation in IL28B and spontaneous clearance of hepatitis C virus.

Hepatitis C virus (HCV) infection is the most common blood-borne infection in the United States, with estimates of 4 million HCV-infected individuals in the United States and 170 million worldwide. Most (70-80%) HCV infections persist and about 30% of individuals with persistent infection develop chronic liver disease, including cirrhosis and hepatocellular carcinoma. Epidemiological, viral and host factors have been associated with the differences in HCV clearance or persistence, and studies have demonstrated that a strong host immune response against HCV favours viral clearance. Thus, variation in genes involved in the immune response may contribute to the ability to clear the virus. In a recent genome-wide association study, a single nucleotide polymorphism (rs12979860) 3 kilobases upstream of the IL28B gene, which encodes the type III interferon IFN-3, was shown to associate strongly with more than a twofold difference in response to HCV drug treatment. To determine the potential effect of rs12979860 variation on outcome to HCV infection in a natural history setting, we genotyped this variant in HCV cohorts comprised of individuals who spontaneously cleared the virus (n = 388) or had persistent infection (n = 620). We show that the C/C genotype strongly enhances resolution of HCV infection among individuals of both European and African ancestry. To our knowledge, this is the strongest and most significant genetic effect associated with natural clearance of HCV, and these results implicate a primary role for IL28B in resolution of HCV infection.

Naturally occurring dominant resistance mutations to hepatitis C virus protease and polymerase inhibitors in treatment-naïve patients.

UNLABELLED: Resistance mutations to hepatitis C virus (HCV) nonstructural protein 3 (NS3) protease inhibitors in <1% of the viral quasispecies may still allow >1000-fold viral load reductions upon treatment, consistent with their reported reduced replicative fitness in vitro. Recently, however, an R155K protease mutation was reported as the dominant quasispecies in a treatment-naïve individual, raising concerns about possible full drug resistance. To investigate the prevalence of dominant resistance mutations against specifically targeted antiviral therapy for HCV (STAT-C) in the population, we analyzed HCV genome sequences from 507 treatment-naïve patients infected with HCV genotype 1 from the United States, Germany, and Switzerland. Phylogenetic sequence analysis and viral load data were used to identify the possible spread of replication-competent, drug-resistant viral strains in the population and to infer the consequences of these mutations upon viral replication in vivo. Mutations described to confer resistance to the protease inhibitors Telaprevir, BILN2061, ITMN-191, SCH6 and Boceprevir; the NS5B polymerase inhibitor AG-021541; and to the NS4A antagonist ACH-806 were observed mostly as sporadic, unrelated cases, at frequencies between 0.3% and 2.8% in the population, including two patients with possible multidrug resistance. Collectively, however, 8.6% of the patients infected with genotype 1a and 1.4% of those infected with genotype 1b carried at least one dominant resistance mutation. Viral loads were high in the majority of these patients, suggesting that drug-resistant viral strains might achieve replication levels comparable to nonresistant viruses in vivo. CONCLUSION: Naturally occurring dominant STAT-C resistance mutations are common in treatment-naïve patients infected with HCV genotype 1. Their influence on treatment outcome should further be characterized to evaluate possible benefits of drug resistance testing for individual tailoring of drug combinations when treatment options are limited due to previous nonresponse to peginterferon and ribavirin.

Evaluation of IL10, IL19 and IL20 gene polymorphisms and chronic hepatitis B infection outcome.

Hepatitis B virus (HBV) infection remains a serious global health problem despite the availability of a highly effective vaccine. Approximately 5% of HBV-infected adults develop chronic hepatitis B, which may result in liver cirrhosis or hepatocellular carcinoma. Variants of interleukin-10 (IL10) have been previously associated with chronic hepatitis B infection and progression to hepatocellular carcinoma. Single nucleotide polymorphisms (SNP; n = 42) from the IL10, IL19 and IL20 gene regions were examined for an association with HBV infection outcome, either chronic or recovered, in a nested case-control study of African Americans and European Americans. Among African Americans, three nominally statistically significant SNP associations in IL10, two in IL20, and one haplotype association were observed with different HBV infection outcomes (P = 0.005-0.04). A SNP (rs1518108) in IL20 deviated significantly from Hardy-Weinberg equilibrium in African Americans, with a large excess of heterozygotes in chronic HBV-infected cases (P = 0.0006), which suggests a strong genetic effect. Among European Americans, a nominally statistically significant SNP association in IL20 and an IL20 haplotype were associated with HBV recovery (P = 0.01-0.04). These results suggest that IL10 and IL20 gene variants influence HBV infection outcome and encourage the pursuit of further studies of these cytokines in HBV pathogenesis.

Platelet count is associated with plasma HIV type 1 RNA and disease progression.

Thrombocytopenia is a common finding among HIV-1-infected individuals. In addition to their function in hemostasis, platelets have been found to play a role in host immune defenses and to directly interact with HIV-1. To explore the role of platelets in HIV-1 infection, we examined the relationship between platelet number and the natural history of HIV-1 disease in the well-characterized Hemophilia Growth and Development Study cohort. In a multivariate analysis platelets were found to be inversely related to plasma HIV-1 RNA with increasing platelets associated with lower plasma HIV-1 RNA levels (p < 0.001). Despite this, increasing platelet count was independently associated with enhanced risk of progression to AIDS and death (p < 0.001 for both). While there may be multiple explanations for these novel observations, they do generate hypotheses related to the potential influence platelets may have on the natural history of HIV-1 disease.

Baseline HIV type 1 coreceptor tropism predicts disease progression.

BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) coreceptor tropism, the ability of the virus to enter cells via CCR5 or CXCR4, is a viral characteristic mediated by the envelope gene. The impact of coreceptor tropism on the natural history of HIV-1 infection has not been fully explored. METHODS: Coreceptor tropism was measured using a recombinant virus single-cycle assay on plasma specimens obtained at baseline from 126 children and adolescents in the Hemophilia Growth and Development Study cohort who were enrolled from 1989 through 1990 and underwent follow-up through 1997. RESULTS: Detectable CXCR4-using virus at baseline was associated with a lower baseline CD4(+) T cell count and a higher plasma HIV-1 RNA level. In addition, it independently predicted a greater decrease in CD4(+) T cell count over time (P<.001) and was associated with a 3.8-fold increased risk of progression to clinical AIDS. CONCLUSIONS: This study demonstrates that coreceptor tropism, as assessed by this single-cycle assay, independently influences the natural history of HIV-1 disease.

Delays in maturation among adolescents with hemophilia and a history of inhibitors.

Inhibitory antibodies to factors VIII or IX have the potential to affect a broad range of outcomes among people with hemophilia; however, their possible effect on growth and maturation has not been explored. We evaluated skeletal maturation (bone age), pubertal progression, serum testosterone levels, height velocity, and stature in the multicenter Hemophilia Growth and Development Study. A total of 333 children and adolescents (mean age, 12.4 years) were enrolled from 1989 to 1990 and followed for 7 years. Of these, 18% (n = 60) had a history of inhibitors. Bone age among HIV(-) adolescents with a history of inhibitors lagged 9 or more months behind those without inhibitors at every age from 12 to 15 years. Those with a history of inhibitors were older at every Tanner stage transition, attained a lower maximum growth velocity, and their serum testosterone levels were significantly lower compared with those without inhibitors. Delays were greater among HIV(+) patients with a history of inhibitors compared with those without inhibitors; however, the differences were generally small and not statistically significant. The results of this investigation underscore the importance of monitoring the growth and maturation of children and adolescents with hemophilia, particularly those with inhibitors.