Genetic discrimination—defined as the denial of rights, privileges, or opportunities or other adverse treatment based solely on genetic information (including family history)—is an important concern to patients, healthcare professionals, lawmakers, and family members at risk for carrying a deleterious gene. Data from the United States, Canada, and Australia were collected from 433 individuals at risk for Huntington disease (HD) who have tested either positive or negative for the gene that causes HD and family members of affected individuals who have a 50% risk for developing the disorder but remain untested. Across all three countries, a total of 46.2% of respondents report genetic discrimination or stigma based on either their family history of HD or genetic testing for the HD gene mutation. We report on the overall incidence of discrimination and stigma in the domains of insurance (25.9%), employment (6.5%), relationships (32.9%), and other transactions (4.6%) in the United States, Canada, and Australia combined. The incidence of self-reported discrimination is less than the overall worry about the risk of discrimination, which is more prevalent in each domain. Despite a relatively low rate of perceived genetic discrimination in the areas of health insurance and employment, compared to the perception of discrimination and stigma in personal relationships, the cumulative burden of genetic discrimination across all domains of experience represents a challenge to those at risk for HD. The effect of this cumulative burden on daily life decisions remains unknown.
survey; employment; insurance; family history; genetic testing
Deer mice (Peromyscus maniculatus) are the main reservoir host for Sin Nombre virus, the primary etiologic agent of hantavirus pulmonary syndrome in North America. Sequential changes in weather and plant productivity (trophic cascades) have been noted as likely catalysts of deer mouse population irruptions, and monitoring and modeling of these phenomena may allow for development of early-warning systems for disease risk. Relationships among weather variables, satellite-derived vegetation productivity, and deer mouse populations were examined for a grassland site east of the Continental Divide and a sage-steppe site west of the Continental Divide in Montana, USA. We acquired monthly deer mouse population data for mid-1994 through 2007 from long-term study sites maintained for monitoring changes in hantavirus reservoir populations, and we compared these with monthly bioclimatology data from the same period and gross primary productivity data from the Moderate Resolution Imaging Spectroradiometer sensor for 2000–06. We used the Random Forests statistical learning technique to fit a series of predictive models based on temperature, precipitation, and vegetation productivity variables. Although we attempted several iterations of models, including incorporating lag effects and classifying rodent density by seasonal thresholds, our results showed no ability to predict rodent populations using vegetation productivity or weather data. We concluded that trophic cascade connections to rodent population levels may be weaker than originally supposed, may be specific to only certain climatic regions, or may not be detectable using remotely sensed vegetation productivity measures, although weather patterns and vegetation dynamics were positively correlated.
Deer mice; hantavirus; MODIS; Peromyscus; prediction; satellites; trophic cascade
This study examines perceived stress and its relationship to depressive symptoms, life changes and functional capacity in a large sample of individuals who are positive for the Huntington disease (HD) gene expansion but not yet diagnosed. Participants were classified by estimated proximity to HD diagnosis (far, mid, near) and compared with a non gene-expanded comparison group. Persons in the mid group had the highest stress scores. A significant interaction between age and time since HD genetic testing was also found. Secondary analyses using data from a different data collection point and including a diagnosed group showed the highest stress scores in the diagnosed group. Possible explanations and implications are discussed.
Huntington disease; perceived stress; depression
Determining the microbiologic etiology of enteric infection remains an elusive goal. Conventional approaches, including culture, microscopy, and antigen-based tests have significant limitations such as limit of detection and the need for multiple procedures. Molecular diagnostics, especially PCR based tests, are rapidly changing research and practice in infectious diseases. Diarrheal disease, with its broad range of potential infectious etiologies, is well suited for multiplex molecular testing. This review highlights examples of currently employed molecular tests, as well as ways in which these tests can be applied in the future. The absence of a gold standard for the microbiologic cause of diarrhea means that the clinical significance of detected organisms may not always be clear. Conventional wisdom is that there should be one main pathogen causing diarrhea, however our thinking is challenged by increased detection of mixed infections. Thus, the successful incorporation of molecular diagnostics for diarrheal disease into practice will require both a careful understanding of the technical aspects and research to define their clinical utility.
diarrhea; molecular diagnosis; PCR; enteropathogens
The identification of clinical and biological markers of disease in persons at risk for Huntington Disease (HD) has increased in efforts to better quantify and characterize the epoch of prodrome prior to clinical diagnosis. Such efforts are critical in the design and implementation of clinical trials for HD so that interventions can occur at a time most likely to increase neuronal survival and maximize daily functioning. A prime consideration in the examination of prodromal individuals is their proximity to diagnosis. It is necessary to quantify proximity so that individual differences in key marker variables can be properly interpreted. We take a data-driven approach to develop an index that can be viewed as a proxy for time to HD diagnosis known as the CAG-Age Product Scaled or CAPS. CAPS is an observed utility variable computed for all genetically at-risk individuals based on age at study entry and CAG repeat length. Results of a longitudinal receiver operating characteristic (ROC) analysis showed that CAPS had a relatively strong ability to predict individuals who became diagnosed, especially in the first 2 years. Bootstrap validation provided evidence that CAPS computed on a new sample from the same population could have similar discriminatory power. Cutoffs for the empirical CAPS distribution can be used to create a classification for mutation-positive individuals (Low-Med-High) that is useful for comparison with the naturally occurring mutation-negative Control group. The classification is an improvement over the one currently in use as it is based on observed data rather than model-based estimated values.
survival analysis; prodromal Huntington disease; PREDICT-HD Study
Individual studies of the genetics of neural tube defects (NTDs) contain results on a small number of genes in each report. To identify genetic risk factors for NTDs, we evaluated potentially functional single nucleotide polymorphisms (SNPs) that are biologically plausible risk factors for NTDs but that have never been investigated for an association with NTDs, examined SNPs that previously showed no association with NTDs in published studies, and tried to confirm previously reported associations in folate-related and non-folate-related genes. We investigated 64 SNPs in 34 genes for association with spina bifida in up to 558 case-families (520 cases, 507 mothers, 457 fathers) and 994 controls in Ireland. Case-control and mother-control comparisons of genotype frequencies, tests of transmission disequilibrium, and log-linear regression models were used to calculate effect estimates. Spina bifida was associated with over-transmission of the LEPR (leptin receptor) rs1805134 minor C allele (genotype relative risk (GRR): 1.5; 95% confidence interval (CI): 1.0, 2.1; P = 0.0264) and the COMT (catechol-O-methyltransferase) rs737865 major T allele (GRR: 1.4; 95% CI: 1.1, 2.0; P = 0.0206). After correcting for multiple comparisons, these individual test P-values exceeded 0.05. Consistent with previous reports, spina bifida was associated with MTHFR 677C>T, T (Brachyury) rs3127334, LEPR K109R, and PDGFRA promoter haplotype combinations. The associations between LEPR SNPs and spina bifida suggest a possible mechanism for the finding that obesity is a NTD risk factor. The association between a variant in COMT and spina bifida implicates methylation and epigenetics in NTDs.
congenital abnormalities; folic acid; neural tube defects; single nucleotide polymorphism; spina bifida
Suggestive, but not conclusive, studies implicate many genetic variants in oral cleft etiology. We used a large, ethnically homogenous study population to test whether reported associations between nonsyndromic oral clefts and 12 genes (CLPTM1, CRISPLD2, FGFR2, GABRB3, GLI2, IRF6, PTCH1, RARA, RYK, SATB2, SUMO1, TGFA) could be confirmed.
Thirty-one single nucleotide polymorphisms (SNPs) in exons, splice sites, and conserved non-coding regions were studied in 509 patients with cleft lip with or without cleft palate (CLP), 383 with cleft palate only (CP), 838 mothers and 719 fathers of patients with oral clefts, and 902 controls from Ireland. Case-control and family-based statistical tests were performed using isolated oral clefts for the main analyses.
In case-control comparisons, the minor allele of PTCH1 A562A (rs2066836) was associated with reduced odds of CLP (OR: 0.29, 95% CI: 0.13–0.64 for homozygotes) whereas the minor allele of PTCH1 L1315P (rs357564) was associated with increased odds of CLP (OR: 1.36, 95% CI: 1.07–1.74 for heterozygotes and OR: 1.56, 95% CI: 1.09–2.24 for homozygotes). The minor allele of one SUMO1 SNP, rs3769817 located in intron 2, was associated with increased odds of CP (OR: 1.45, 95% CI: 1.06–1.99 for heterozygotes). Transmission disequilibrium was observed for the minor allele of TGFA V159V (rs2166975) which was over-transmitted to CP cases (P=0.041).
For 10 of the 12 genes, this is the largest candidate gene study of nonsyndromic oral clefts to date. The findings provide further evidence that PTCH1, SUMO1, and TGFA contribute to nonsyndromic oral clefts.
cleft lip; cleft palate; congenital abnormalities
Hantaviruses are distributed throughout the United States and are the etiologic agents for hantavirus pulmonary syndrome and hemorrhagic fever with renal syndrome. Hantavirus genotypes and epidemiologic patterns vary spatially across the United States. While several longitudinal studies have been performed in the western United States, little is known about the virus in the eastern United States. We undertook a longitudinal study of hantaviruses in the primary rodent reservoir host in central Pennsylvania, Peromyscus leucopus. Prevalence of hantavirus antibodies varied both by year and site, but was not correlated with host abundance. Males were significantly more likely to have antibodies to a hantavirus than females, and both antibody sero-conversion and antibody prevalence increased with mass class (indicator for age). Our findings suggest that one or more hantaviruses are present and circulating among P. leucopus of central Pennsylvania, and understanding the dynamics in this region could help prevent zoonotic transmission to humans. Our aim was to describe the differences in epizootiology of hantavirus infection in rodents from various geographical locations to enable improved analysis of the risk of rodent-to-human transmission and obtain insights that may indicate improved means of disease intervention.
Epizootiology; Hanta-specific antibodies; Hantavirus; Peromyscus; White-footed mouse
Sin Nombre hantavirus (SNV), hosted by the North American deermouse (Peromyscus maniculatus), causes hantavirus pulmonary syndrome (HPS) in North America. Most transmission studies in the host were conducted under artificial conditions, or extrapolated information from mark-recapture data. Previous studies using experimentally infected deermice were unable to demonstrate SNV transmission. We explored SNV transmission in outdoor enclosures using naturally infected deermice. Deermice acquiring SNV in enclosures had detectable viral RNA in blood throughout the acute phase of infection and acquired significantly more new wounds (indicating aggressive encounters) than uninfected deermice. Naturally-infected wild deermice had a highly variable antibody response to infection, and levels of viral RNA sustained in blood varied as much as 100-fold, even in individuals infected with identical strains of virus. Deermice that infected other susceptible individuals tended to have a higher viral RNA load than those that did not infect other deermice. Our study is a first step in exploring the transmission ecology of SNV infection in deermice and provides new knowledge about the factors contributing to the increase of the prevalence of a zoonotic pathogen in its reservoir host and to changes in the risk of HPS to human populations. The techniques pioneered in this study have implications for a wide range of zoonotic disease studies.
We report the results of an investigation of a small outbreak of hantavirus pulmonary syndrome in 2002 in the Department of Santa Cruz, Bolivia, where the disease had not previously been reported. Two cases were initially reported. The first case was a physician infected with Laguna Negra virus during a weekend visit to his ranch. Four other persons living on the ranch were IgM antibody-positive, two of whom were symptomatic for mild hantavirus pulmonary syndrome. The second case was a migrant sugarcane worker. Although no sample remained to determine the specific infecting hantavirus, a virus 90% homologous with Río Mamoré virus was previously found in small-eared pygmy rice rats (Oligoryzomys microtis) trapped in the area. An antibody prevalence study conducted in the region as part of the outbreak investigation showed 45 (9.1%) of 494 persons to be IgG positive, illustrating that hantavirus infection is common in Santa Cruz Department. Precipitation in the months preceding the outbreak was particularly heavy in comparison to other years, suggesting a possible climatic or ecological influence on rodent populations and risk of hantavirus transmission to humans. Hantavirus infection appears to be common in the Santa Cruz Department, but more comprehensive surveillance and field studies are needed to fully understand the epidemiology and risk to humans.
Hantaviruses can evoke a severe, acute disease in humans known as hantavirus pulmonary syndrome with case fatalities up to 70%. Pathogenic hantaviruses are carried by rodents, with each virus species usually carried by a specific species of rodent. Hantavirus-host reservoir pairs continue to be discovered and details of the epidemiology and risk of hantaviruses to humans continue to emerge. We report the results of an investigation of a small outbreak of hantavirus pulmonary syndrome in 2002 in the Department of Santa Cruz, Bolivia, where the disease had not previously been reported. Two cases were initially noted, with four additional persons shown to be recently infected with hantaviruses through thorough field investigation and antibody evidence. An antibody prevalence study conducted as part of the outbreak investigation showed over 9% of the population studied to have previous exposure to hantaviruses. Precipitation in the months preceding the outbreak was particularly heavy in comparison to other years, suggesting a possible climatic influence on rodent populations and risk of hantavirus transmission to humans. Hantavirus infection appears to be common in the Santa Cruz Department, but more comprehensive surveillance and field studies are needed to fully understand the epidemiology and risk to humans.
Neural tube defects (NTDs) are common birth defects (~1 in 1000 pregnancies in the US and Europe) that have complex origins, including environmental and genetic factors. A low level of maternal folate is one well-established risk factor, with maternal periconceptional folic acid supplementation reducing the occurrence of NTD pregnancies by 50-70%. Gene variants in the folate metabolic pathway (e.g., MTHFR rs1801133 (677 C > T) and MTHFD1 rs2236225 (R653Q)) have been found to increase NTD risk. We hypothesized that variants in additional folate/B12 pathway genes contribute to NTD risk.
A tagSNP approach was used to screen common variation in 82 candidate genes selected from the folate/B12 pathway and NTD mouse models. We initially genotyped polymorphisms in 320 Irish triads (NTD cases and their parents), including 301 cases and 341 Irish controls to perform case–control and family based association tests. Significantly associated polymorphisms were genotyped in a secondary set of 250 families that included 229 cases and 658 controls. The combined results for 1441 SNPs were used in a joint analysis to test for case and maternal effects.
Nearly 70 SNPs in 30 genes were found to be associated with NTDs at the p < 0.01 level. The ten strongest association signals (p-value range: 0.0003–0.0023) were found in nine genes (MFTC, CDKN2A, ADA, PEMT, CUBN, GART, DNMT3A, MTHFD1 and T (Brachyury)) and included the known NTD risk factor MTHFD1 R653Q (rs2236225). The single strongest signal was observed in a new candidate, MFTC rs17803441 (OR = 1.61 [1.23-2.08], p = 0.0003 for the minor allele). Though nominally significant, these associations did not remain significant after correction for multiple hypothesis testing.
To our knowledge, with respect to sample size and scope of evaluation of candidate polymorphisms, this is the largest NTD genetic association study reported to date. The scale of the study and the stringency of correction are likely to have contributed to real associations failing to survive correction. We have produced a ranked list of variants with the strongest association signals. Variants in the highest rank of associations are likely to include true associations and should be high priority candidates for further study of NTD risk.
Neural tube defects; Spina bifida; Folic acid; One-carbon metabolism; Candidate gene
Patients with peripheral arterial disease (PAD) have lower functional capacity and worse clinical outcomes than age and gender matched patients. Few data exist on the relationship of PAD with functional and clinical outcomes in heart failure (HF) patients. We sought to compare HF patients with and without PAD for baseline functional capacity, response to exercise training, and clinical outcomes. HF-ACTION was a randomized controlled trial comparing usual care to structured exercise training plus usual care in HF patients with an ejection fraction ≤ 35% and NYHA class II – IV heart failure symptoms. Cardiopulmonary exercise (CPX) testing occurred at enrollment, 3 months, and 1 year. Clinical follow-up occurred up to 4 years. Of the 2331 HF-ACTION patients, 157 (6.8%) had PAD. At baseline, HF patients with PAD had a lower exercise duration (8.0 vs. 9.8 minutes, p<0.001), lower peak oxygen consumption (VO2) (12.5 vs. 14.6 mL/kg/min, p<0.001), and shorter six minute walking distance (306 vs. 371 meters, p<0.001) compared to HF patients without PAD. At three months, HF patients with PAD had less improvement on CPX testing [exercise duration (0.5 vs. 1.1 minutes; p=0.002) and peak VO2 (mean change; 0.1 vs. 0.6 mL/kg/min; p=0.04)] compared to HF patients without PAD. PAD was an independent predictor of all-cause death or hospitalization [hazard ratio (95% CI); 1.31 (1.06 – 1.62), p=0.011]. PAD patients with HF have depressed baseline exercise capacity and decreased response to exercise training. In conclusion, PAD is an independent predictor of all-cause death or hospitalization in HF patients.
Peripheral Arterial Disease; Heart Failure; Exercise Training
Several studies have suggested a greater risk of suicide in Huntington disease (HD); however, unique risk factors for suicide in HD are not established.
We sought to determine risk factors for suicidal behavior, defined as suicide or attempted suicide, in prodromal HD.
From the prospective PREDICT-HD cohort, we identified 735 cases with HD gene expansion but no manifest symptoms of HD and 194 non-gene-expanded controls. In survival analysis, a number of potential risk factors for suicidal behavior were assessed, including symptoms of depression, hopelessness, substance abuse, marital status, gender, and psychiatric history.
During a mean of 3.7 years of prospective follow-up, 12 cases (1.6%) attempted suicide and 1 completed suicide (0.1%). No suicides were observed among controls. In univariate Cox proportional hazards regression models, a history of suicide attempts (HR 8.5, 95% CI 2.8–26.1, p < 0.0002) and a Beck Depression Inventory II score >13 (HR 7.2, 95% CI 2.3–22.0, p < 0.0006) were associated with suicidal behavior. These risk factors had independent effects in multivariate models. A history of incarceration in the past 2 years was also associated (HR 12.5, 95% CI 2.7–56.6, p < 0.002), though uncommon. No further risk factors were identified.
A history of suicide attempts and the presence of depression are strongly predictive of suicidal behavior in prodromal HD. As these risk factors are among the most robust risk factors for suicide, established suicide risk factors appear applicable to those with prodromal HD.
Copyright © 2011 S. Karger AG, Basel
Attempted suicide; Cohort study; Huntington disease; Major depressive disorder; Risk factors; Suicide
Surveys of wildlife host-pathogen systems often document clear seasonal variation in transmission; conclusions concerning the relationship between host population density and transmission vary. In the field, effects of seasonality and population density on natural disease cycles are challenging to measure independently, but laboratory experiments may poorly reflect what happens in nature. Outdoor manipulative experiments are an alternative that controls for some variables in a relatively natural environment. Using outdoor enclosures, we tested effects of North American deermouse (Peromyscus maniculatus) population density and season on transmission dynamics of Sin Nombre hantavirus. In early summer, mid-summer, late summer, and fall 2007–2008, predetermined numbers of infected and uninfected adult wild deermice were released into enclosures and trapped weekly or bi-weekly. We documented 18 transmission events and observed significant seasonal effects on transmission, wounding frequency, and host breeding condition. Apparent differences in transmission incidence or wounding frequency between high- and low-density treatments were not statistically significant. However, high host density was associated with a lower proportion of males with scrotal testes. Seasonality may have a stronger influence on disease transmission dynamics than host population density, and density effects cannot be considered independent of seasonality.
Both taking folic acid-containing vitamins around conception and consuming food fortified with folic acid have been reported to reduce omphalocele rates. Genetic factors are etiologically important in omphalocele as well; our pilot study showed a relationship with the folate metabolic enzyme gene methylenetetrahydrofolate reductase (MTHFR). We studied 169 non-aneuploid omphalocele cases and 761 unaffected, matched controls from all New York State births occurring between 1998 and 2005 to look for associations with single nucleotide polymorphisms (SNPs) known to be important in folate, vitamin B12, or choline metabolism. In the total study population, variants in the transcobalamin receptor gene (TCblR), rs2232775 (Q8R), and the MTHFR gene, rs1801131 (1298A>C), were significantly associated with omphalocele. In African-Americans significant associations were found with SNPs in genes for the vitamin B12 transporter (TCN2) and the vitamin B12 receptor (TCblR). A SNP in the homocysteine-related gene, betaine-homocysteine S-methyltransferase (BHMT), rs3733890 (R239Q), was significantly associated with omphalocele in both African-Americans and Asians. Only the TCblR association in the total population remained statistically significant if Bonferroni correction was applied. The finding that transcobalamin receptor (TCblR) and transporter (TCN2) SNPs and a BHMT SNP were associated with omphalocele suggests that disruption of methylation reactions, in which folate, vitamin B12, and homocysteine play critical parts, may be a risk factor for omphalocele. Our data, if confirmed, suggest that supplements containing both folic acid and vitamin B12 may be beneficial in preventing omphaloceles.
omphalocele; folate; vitamin B12; homocysteine; transcobalamin; transcobalamin receptor
Although methylenetetrahydrofolate reductase, a folate enzyme gene, has been associated with idiopathic male infertility, few studies have examined other folate-related metabolites and genes. We investigated whether idiopathic male infertility is associated with variants in folate, vitamin B12 (B12) and total homocysteine (tHcy)-related genes and measured these metabolites in blood. We conducted a case–control study that included 153 men with idiopathic infertility and 184 fertile male controls recruited at the Fertility Center and Antenatal Care Center, University Hospital, Malmö and Lund, Sweden. Serum folate, red cell folate (RCF), serum B12, plasma tHcy and semen quality were measured. Subjects were genotyped for 20 common variants in 12 genes related to folate/B12/homocysteine metabolism. Metabolite concentrations and genotype distributions were compared between cases and controls using linear and logistic regression with adjustment for covariates. The phosphatidylethanolamine N-methyltransferase (PEMT) M175V and TCblR rs173665 polymorphisms were significantly associated with infertility (P = 0.01 and P = 0.009, respectively), but not with semen quality. Among non-users of supplements, infertile men had lower serum folate concentrations than fertile men (12.89 vs. 14.73 nmol l−1; P = 0.02), but there were no significant differences in RCF, B12 or tHcy. Folate, B12 and tHcy concentrations were not correlated with any semen parameters. This study provides little support for low folate or B12 status in the pathogenesis of idiopathic male infertility. Although additional data are needed to confirm these initial findings, our results suggest that PEMT and TCblR, genes involved in choline and B12 metabolism, merit further investigation in idiopathic male infertility.
folate; idiopathic male infertility; semen quality; vitamin B12
Periconceptional use of folic acid prevents most neural tube defects (NTDs). Whether folic acid and/or multivitamins can prevent other congenital anomalies is not clear. This study tested whether maternal blood levels of folate and vitamin B12 in pregnancies affected by congenital malformations excluding NTDs are lower when compared to non-affected pregnancies.
We measured pregnancy red cell folate (RCF), vitamin B12, and homocysteine (tHcy) concentrations in blood samples taken at the first antenatal clinic in Dublin maternity hospitals in 1986–1990 when vitamin supplementation was rare. The cases were mothers who delivered a baby with a congenital malformation other than NTD identified by the Dublin EUROCAT Registry; controls were a systematic sample of mothers of offspring without congenital malformations from the same hospitals in the same time period.
The median maternal levels of RCF and tHcy did not differ significantly between cases and controls for any of the congenital malformation groups examined (RCF: all malformations 275.9 ug/L v controls 271.2; p=0.77; tHcy: all malformations 7.5 umol/L v controls 7.6; p=0.57). In an unadjusted analysis vitamin B12 was significantly higher in case-mothers whose babies had cleft palate only (p=0.006), musculoskeletal malformations (p=0.034) and midline defects (p=0.039) but not after adjustment for multiple testing.
Our data suggest that low maternal folate and B12 levels or high tHcy levels in early pregnancy are not associated with all congenital malformations excluding NTDs. Fortification with folic acid or B12 may not have a beneficial effect in the prevention of these anomalies.
Inhibition of N-myristoyltransferase has been validated pre-clinically as a target for the treatment of fungal and trypanosome infections, using species-specific inhibitors. In order to identify inhibitors of protozoan NMTs, we chose to screen a diverse subset of the Pfizer corporate collection against Plasmodium falciparum and Leishmania donovani NMTs. Primary screening hits against either enzyme were tested for selectivity over both human NMT isoforms (Hs1 and Hs2) and for broad-spectrum anti-protozoan activity against the NMT from Trypanosoma brucei. Analysis of the screening results has shown that structure-activity relationships (SAR) for Leishmania NMT are divergent from all other NMTs tested, a finding not predicted by sequence similarity calculations, resulting in the identification of four novel series of Leishmania-selective NMT inhibitors. We found a strong overlap between the SARs for Plasmodium NMT and both human NMTs, suggesting that achieving an appropriate selectivity profile will be more challenging. However, we did discover two novel series with selectivity for Plasmodium NMT over the other NMT orthologues in this study, and an additional two structurally distinct series with selectivity over Leishmania NMT. We believe that release of results from this study into the public domain will accelerate the discovery of NMT inhibitors to treat malaria and leishmaniasis. Our screening initiative is another example of how a tripartite partnership involving pharmaceutical industries, academic institutions and governmental/non-governmental organisations such as Medical Research Council and Wellcome Trust can stimulate research for neglected diseases.
Inhibition of N-myristoyltransferase has been validated pre-clinically as a target for the treatment of fungal and trypanosome infections, using species-specific inhibitors. In order to identify inhibitors of protozoan NMTs, we chose to screen a diverse subset of the Pfizer corporate collection against Plasmodium falciparum and Leishmania donovani NMTs. Primary screening hits against either enzyme were tested for selectivity over both human NMT isoforms (HsNMT1 and HsNMT2) and for broad-spectrum anti-protozoan activity against the NMT from Trypanosoma brucei. We have identified eight series of protozoan NMT inhibitors, six having good selectivity for either Plasmodium or Leishmania NMTs over the other orthologues in this study. We believe that all of these series could form the basis of medicinal chemistry programs to deliver drug candidates against either malaria or leishmaniasis. Our screening initiative is another example of how a tripartite partnership involving pharmaceutical industries, academic institutions and governmental/non-governmental organisations such as the UK Medical Research Council and Wellcome Trust can stimulate research for neglected diseases.
Polymorphisms within the MTHFD1L gene were previously associated with risk of neural tube defects in Ireland. We sought to test the most significant MTHFD1L polymorphisms for an association with risk of cleft in an Irish cohort. This required the development of a new melting curve assay to genotype the technically challenging MTHFD1L triallelic deletion/insertion polymorphism (rs3832406).
Melting curve analysis was used to genotype the MTHFD1L triallelic deletion/insertion polymorphism (rs3832406) and a Single Nucleotide Polymorphism rs17080476 in an Irish cohort consisting of 981 Irish case-parent trios and 1,008 controls. Tests for association with nonsyndromic cleft lip with or without cleft palate and cleft palate included case/control analysis, mother/control analysis and Transmission Disequilibrium Tests of case-parent trios.
A successful melting curve genotyping assay was developed for the deletion/insertion polymorphism (rs3832406). The TDT analysis initially showed that the rs3832406 polymorphism was associated with isolated cleft lip with or without cleft palate. However, corrected p-values indicated that this association was not significant.
Melting Curve Analysis can be employed to successfully genotype challenging polymorphisms such as the MTHFD1L triallelic deletion/insertion polymorphism (DIP) reported here (rs3832406) and is a viable alternative to capillary electrophoresis. Corrected p-values indicate no association between MTHFD1L and risk of cleft in an Irish cohort.
folic acid; folate; NHANES; folic acid fortification
New technology for large-scale genotyping has created new challenges for statistical analysis. Correcting for multiple comparison without discarding true positive results and extending methods to triad studies are among the important problems facing statisticians. We present a one-sample permutation test for testing transmission disequilibrium hypotheses in triad studies, and show how this test can be used for multiple single nucleotide polymorphism (SNP) testing. The resulting multiple comparison procedure is shown in the case of the transmission disequilibrium test to control the familywise error. Furthermore, this procedure can handle multiple possible modes of risk inheritance per SNP. The resulting permutational procedure is shown through simulation of SNP data to be more powerful than the Bonferroni procedure when the SNPs are in linkage disequilibrium. Moreover, permutations implicitly avoid any multiple comparison correction penalties when the SNP has a rare allele. The method is illustrated by analyzing a large candidate gene study of neural tube defects and an independent study of oral clefts, where the smallest adjusted p-values using the permutation procedure are approximately half those of the Bonferroni procedure. We conclude that permutation tests are more powerful for identifying disease-associated SNPs in candidate gene studies and are useful for analysis of triad studies.
Exchangeable; familywise error rate; linkage disequilibrium; power
Although delirium is a common medical comorbidity with altered cognition as its defining feature, few publications have addressed the neuropsychological prodrome, profile, and recovery of patients tested during delirium. We characterize neuropsychological performance in 54 hemapoietic stem cell/bone marrow transplantation (BMT) patients shortly before, during, and after delirium and in BMT patients without delirium and 10 healthy adults. Patients were assessed prospectively before and after transplantation using a brief battery. BMT patients with delirium performed more poorly than comparisons and those without delirium on cross-sectional and trend analyses. Deficits were in expected areas of attention and memory, but also in psychomotor speed and learning. The patients with delirium did not return to normative “average” on any test during observation. Most tests showed a mild decline in the visit before delirium, a sharp decline with delirium onset, and variable performance in the following days. This study adds to the few investigations of neuropsychological performance surrounding delirium and provides targets for monitoring and early detection; Trails A and B, RBANS Coding, and List Recall may be useful for delirium assessment.
Bone marrow transplantation; Cognition; Cancer; Attention; Delirium
To study the effect of in-utero alcohol exposure on the insulin-like growth factor axis (IGF) and leptin during infancy and childhood, considering that exposed children may exhibit pre- and postnatal growth retardation.
We prospectively identified heavily drinking pregnant women who consumed on average 4 or more drinks of ethanol per day (≥48 g/day) and assessed growth in 69 of their offspring and an unexposed control group of 83 children, measuring serum IGF-I (radioimmunoassay), IGF-II (immunoradiometric assay, IRMA), insulin-like growth factor-binding protein 3 (IGFBP-3) (IRMA) and leptin (IRMA) at 1 month and 1, 2, 3, 4, and 5 years of age.
IGF-II levels increased with age in both groups, but the rate of increase was significantly higher in exposed children, and levels were significantly higher in ethanol-exposed children at 3, 4, and 5 years of age. In exposed children, IGF-I levels were higher at 3 and 4 years and leptin levels were significantly lower at 1 and 2 years. Exposed subjects showed a much lower correlation between IGF-I and growth parameters than unexposed subjects.
Exposure to ethanol during pregnancy increases IGF-I and IGF-II and decreases leptin during early childhood. The increase in serum IGF-II concentrations in ethanol-exposed children suggests that this hormone should be explored as a potential marker for prenatal alcohol exposure.
Fetal alcohol syndrome; Pregnancy; Alcohol abuse; Insulin-like growth factor I; Insulin-like growth factor II
Delirium is associated with a host of negative outcomes, including increased risk of mortality, longer hospital stay, and poor long-term cognitive function. The pathophysiology of delirium is not well understood. Cancer patients undergoing a bone marrow transplant (BMT) are at high risk for developing delirium and Proton Magnetic Resonance Spectroscopy (1H-MRS) could lead to better understanding of the delirium process.
Fourteen BMT patients and 10 controls completed 1H-MRS, positioned above the corpus callosum, shortly after delirium onset or at study end if no delirium occurred.
In the BMT-delirium group, statistically significantly elevated tCho/tCr was found in contrast to the BMT-no delirium group (p<0.05). The BMT–delirium group also showed statistically significantly lesser NAA/tCho compared to both controls (p=0.01) and the BMT–no delirium group (p=0.04).
Elevated choline and reduced NAA indicate inflammatory processes and white matter damage as well as neuronal metabolic impairment. Further research is needed to separate the choline peaks, as well as more detailed collection of medication regimens to determine whether a higher choline concentration is a function of the delirium process or cancer treatment effects.
delirium; spectroscopy; choline; cancer; magnetic resonance imaging; cognition
Huntington’s disease is an autosomal dominant brain disease. Although conceptualized as a neurodegenerative disease of the striatum, a growing number of studies challenge this classic concept of Huntington’s disease aetiology. Intracranial volume is the tissue and fluid within the calvarium and is a representation of the maximal brain growth obtained during development. The current study reports intracranial volume obtained from an magnetic resonance imaging brain scan in a sample of subjects (n = 707) who have undergone presymptomatic gene testing. Participants who are gene-expanded but not yet manifesting the disease (prodromal Huntington’s disease) are compared with subjects who are non-gene expanded. The prodromal males had significantly smaller intracranial volume measures with a mean volume that was 4% lower compared with controls. Although the prodromal females had smaller intracranial volume measures compared with their controls, this was not significant. The current findings suggest that mutant huntingtin can cause abnormal development, which may contribute to the pathogenesis of Huntington’s disease.
brain; brain imaging; brain volumes