A functional microsatellite of the macrophage migration inhibitory factor gene associated with meningococcal disease.

Macrophage migration inhibitory factor (MIF) is an abundantly expressed proinflammatory cytokine playing a critical role in innate immunity and sepsis and other inflammatory diseases. We examined whether functional MIF gene polymorphisms (-794 CATT(5-8) microsatellite and -173 G/C SNP) were associated with the occurrence and outcome of meningococcal disease in children. The CATT(5) allele was associated with the probability of death predicted by the Pediatric Index of Mortality 2 (P=0.001), which increased in correlation with the CATT(5) copy number (P=0.04). The CATT(5) allele, but not the -173 G/C alleles, was also associated with the actual mortality from meningoccal sepsis [OR 2.72 (1.2-6.4), P=0.02]. A family-based association test (i.e., transmission disequilibrium test) performed in 240 trios with 1 afflicted offspring indicated that CATT(5) was a protective allele (P=0.02) for the occurrence of meningococcal disease. At baseline and after stimulation with Neisseria meningitidis in THP-1 monocytic cells or in a whole-blood assay, CATT(5) was found to be a low-expression MIF allele (P=0.005 and P=0.04 for transcriptional activity; P=0.09 and P=0.09 for MIF production). Taken together, these data suggest that polymorphisms of the MIF gene affecting MIF expression are associated with the occurrence, severity, and outcome of meningococcal disease in children.

Comprehensive sequence analysis of nine Usher syndrome genes in the UK National Collaborative Usher Study.

BACKGROUND: Usher syndrome (USH) is an autosomal recessive disorder comprising retinitis pigmentosa, hearing loss and, in some cases, vestibular dysfunction. It is clinically and genetically heterogeneous with three distinctive clinical types (I-III) and nine Usher genes identified. This study is a comprehensive clinical and genetic analysis of 172 Usher patients and evaluates the contribution of digenic inheritance. METHODS: The genes MYO7A, USH1C, CDH23, PCDH15, USH1G, USH2A, GPR98, WHRN, CLRN1 and the candidate gene SLC4A7 were sequenced in 172 UK Usher patients, regardless of clinical type. RESULTS: No subject had definite mutations (nonsense, frameshift or consensus splice site mutations) in two different USH genes. Novel missense variants were classified UV1-4 (unclassified variant): UV4 is 'probably pathogenic', based on control frequency <0.23%, identification in trans to a pathogenic/probably pathogenic mutation and segregation with USH in only one family; and UV3 ('likely pathogenic') as above, but no information on phase. Overall 79% of identified pathogenic/UV4/UV3 variants were truncating and 21% were missense changes. MYO7A accounted for 53.2%, and USH1C for 14.9% of USH1 families (USH1C:c.496+1G>A being the most common USH1 mutation in the cohort). USH2A was responsible for 79.3% of USH2 families and GPR98 for only 6.6%. No mutations were found in USH1G, WHRN or SLC4A7. CONCLUSIONS: One or two pathogenic/likely pathogenic variants were identified in 86% of cases. No convincing cases of digenic inheritance were found. It is concluded that digenic inheritance does not make a significant contribution to Usher syndrome; the observation of multiple variants in different genes is likely to reflect polymorphic variation, rather than digenic effects.

Polymorphisms in PARP, IL1B, IL4, IL10, C1INH, DEFB1, and DEFA4 in meningococcal disease in three populations.

The pathogenesis of meningococcal infections involves activation of the complement system, proinflammatory and anti-inflammatory mediators, antimicrobial peptides, and apoptosis. We hypothesized that variations in genes encoding these products are involved in the susceptibility to and severity of pediatric meningococcal infections. Polymorphisms in poly (adenosine diphosphate-ribose) polymerase (PARP), serine protease C1 inhibitor (C1INH), IL4, IL10 and IL1B, alpha-defensin 4, and beta-defensin 1 (DEFB1) were analyzed in two independent Caucasian case control cohorts from the United Kingdom and the Netherlands and in a family-based transmission disequilibrium test cohort from the UK. In the UK case control cohort, the DEFB1 -44 G/G homozygous genotype was overrepresented in patients with meningococcal disease compared with the G/C and C/C genotypes when combined (odds ratio, 1.57; 95% confidence interval, 1.12-2.20). The transmission disequilibrium test analysis did not confirm this, but did find an association and linkage of the IL4 -524 and the C1INH 480 polymorphisms with susceptibility to meningococcal infection. Hematological failure was present more often in UK patients with the DEFB1 -44 G/G genotype compared with the C allele carriers (odds ratio, 2.17; 95% confidence interval, 1.22-3.85). Additional studies are necessary to elucidate the conflicting results obtained for the DEFB1, IL4, and C1INH polymorphisms and their role in susceptibility to and severity of meningococcal disease.

Development of a genotyping microarray for Usher syndrome.

BACKGROUND: Usher syndrome, a combination of retinitis pigmentosa (RP) and sensorineural hearing loss with or without vestibular dysfunction, displays a high degree of clinical and genetic heterogeneity. Three clinical subtypes can be distinguished, based on the age of onset and severity of the hearing impairment, and the presence or absence of vestibular abnormalities. Thus far, eight genes have been implicated in the syndrome, together comprising 347 protein-coding exons. METHODS: To improve DNA diagnostics for patients with Usher syndrome, we developed a genotyping microarray based on the arrayed primer extension (APEX) method. Allele-specific oligonucleotides corresponding to all 298 Usher syndrome-associated sequence variants known to date, 76 of which are novel, were arrayed. RESULTS: Approximately half of these variants were validated using original patient DNAs, which yielded an accuracy of >98%. The efficiency of the Usher genotyping microarray was tested using DNAs from 370 unrelated European and American patients with Usher syndrome. Sequence variants were identified in 64/140 (46%) patients with Usher syndrome type I, 45/189 (24%) patients with Usher syndrome type II, 6/21 (29%) patients with Usher syndrome type III and 6/20 (30%) patients with atypical Usher syndrome. The chip also identified two novel sequence variants, c.400C>T (p.R134X) in PCDH15 and c.1606T>C (p.C536S) in USH2A. CONCLUSION: The Usher genotyping microarray is a versatile and affordable screening tool for Usher syndrome. Its efficiency will improve with the addition of novel sequence variants with minimal extra costs, making it a very useful first-pass screening tool.

Factor H, a regulator of complement activity, is a major determinant of meningococcal disease susceptibility in UK Caucasian patients.

Defence against Neisseria meningitidis involves complement-mediated bactericidal activity. Factor H (fH) down-regulates complement activation. A putatively functional single-nucleotide-polymorphism (SNP) exists within a presumed nuclear-factor-kappa-B responsive element (NF-kB) in the fH gene (C-496T). Genetic and functional investigations were carried out to determine whether C-496T has a role in meningococcal disease (MD) susceptibility. Genetic susceptibility was investigated in 2 independent studies, a case-control and family-based transmission-disequilibrium-test (TDT), using 2 separate cohorts of UK Caucasian patients. MD susceptibility was both genetically associated with the C/C homozygous genotype (OR = 2.0, 95% CI 1.3 - 3.2, p = 0.001) and linked to the C allele (p = 0.04), the association being most significant in serogroup C infected patients (OR = 2.9, 95% CI 1.6 - 5.5, p = 0.0002). FH serum concentrations were also associated with C-496T genotype, with highest fH concentrations in C/C homozygous individuals (p = 0.01). Functional studies showed NF-kappa-B binding to the C-496T-containing region and that pre-incubation of fH with meningococci reduced bactericidal activity and increased meningococci B and C survival in blood. This study shows that C-496T is both associated and linked with MD and that individuals possessing the fH C-496T C/C genotype are more likely to have increased serum fH protein levels, have reduced bactericidal activity against meningococci and be at an increased risk of contracting MD.

Role of functional plasminogen-activator-inhibitor-1 4G/5G promoter polymorphism in susceptibility, severity, and outcome of meningococcal disease in Caucasian children.

OBJECTIVE: Meningococcal sepsis invariably is associated with coagulopathy. We have previously reported an association between mortality rate in meningococcal disease and the functional 4G/5G promoter polymorphism of the plasminogen-activator-inhibitor (PAI)-1 gene in a small patient cohort. In a much larger cohort, we aimed to confirm these results and further investigate the role of the 4G/5G polymorphism in determining susceptibility, outcome, and complications of disease.DESIGN Susceptibility was investigated in two separate studies, a case-control study and a family-based transmission study, each test using a separate patient cohort. Severity was investigated using clinical diagnosis, the presence of vascular complications, Pediatric Risk of Mortality (PRISM)-predicted morality, and actual mortality. SETTING: University hospital and laboratories. SUBJECTS: Subjects were 510 UK pediatric patients, 210 parents of patients, and 155 UK Caucasian controls. INTERVENTIONS: DNA extraction and 4G/5G PAI-1 genotyping was carried out using published techniques. MEASUREMENTS AND MAIN RESULTS: Predicted mortality distribution differed significantly between genotypes (p =.05) with a significantly higher median PRISM in the 4G/4G (41.1%) than the 4G/5G (23.4%) and 5G/5G (19.0%) genotyped patients combined (p =.02). Actual mortality rate was significantly associated with both genotype (chi-square = 14.8, p =.001) and allele frequencies (chi-square = 14.0, p <.0001), with more deaths in the 4G/4G (28.4%) than the 4G/5G and 5G/5G genotyped patients combined (14.9%; chi-square = 7.9; p =.005; risk ratio, 1.9; 95% confidence interval, 1.2-3.0). Logistic regression indicated a 40% and 91% reduction in the odds of dying if a patient was either 4G/5G or 5G/5G, respectively, in comparison to a 4G homozygous patient. When analyzed by clinical diagnosis, the association with death was found only in the sepsis group (chi-square = 18.7, p <.0001; risk ratio, 2.7; 95% confidence interval, 1.6-4.6). In survivors of disease, a significantly higher proportion of 4G/4G patients suffered from vascular complications (chi-square = 6.7, p =.03; risk ratio, 2.4; 95% confidence interval, 1.1-5.0). The 4G/5G polymorphism was not associated or linked with susceptibility (case-control result, p =.6; family-based transmission study results, p =.2). CONCLUSIONS: This study confirms that Caucasian pediatric patients carrying the functional PAI-1 4G/4G genotype are at an increased risk of developing vascular complications and dying from meningococcal disease.