Biological monitoring of occupational exposure to low levels of benzene.

To obtain reference values for the biological monitoring of benzene, the kinetics of benzene were studied in volunteers. Benzene in blood and expired air could easily be followed until the next morning after a 4-h exposure to a benzene concentration of 10 cm3.m-3. Even after exposure to 1.7 cm3.m-3 the benzene levels in the morning blood and expired air samples differed from those in unexposed subjects. One hour after exposure to 10 and 1.7 cm3.m-3 the mean levels of benzene were 238 and 25 nmol.l-1 in blood and 13.2 and 2.5 mumol.m-3 in exhaled air, respectively. It was concluded that, at high benzene levels (approximately 10 cm3.m-3), samples collected 16 h after exposure reflect the body burden of benzene, while at low exposure (< 1 cm3.m-3) samples collected 1 h after exposure may be used to estimate the exposure over the preceding few hours. Exposure to benzene from smoking is a potential confounder in estimating occupational exposure to low levels of benzene.     

PATHOLOGY OF LONG-CHAIN 3-HYDROXYACYL-COA DEHYDROGENASE DEFICIENCY CAUSED BY THE G1528C MUTATION

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency is a recently discovered disorder affecting the mitochondrial-oxidation of fatty acids. There have been few reports of the pathologic findings in-oxidation defects. We examined pathologic specimens from 16 patients with this disorder (11 patients were homozygous for the common mutation G1528C, 5 patients were siblings with a similar clinical presentation). Autopsies were performed on all 15 patients who died, and liver biopsy specimens were available from 8 patients. Hepatomegaly and steatosis of the liver, found in every patient, were often combined with fibrosis or cirrhosis. Cardiomegaly and accumulation of fat in the myocardium, renal tubules, and skeletal muscle were found in many patients. A detailed neuropathologic examination was performed on six patients, and brain specimens obtained at autopsy were examined in four others. In general, neuropathologic findings were mild and unspecific, but vacuolization was detected in the deep gray matter and in the cerebellum and brain stem nuclei of five patients. In one patient the vacuolization was prominent; in the other four it was milder and more focal. The vacuoles seemed to be either in the neuropil or associated with swollen hydropic cells. The uniform pattern of histopathologic changes facilitates the diagnostics in this severe disorder, allowing opportunities for therapy and prenatal diagnosis.     

Analysis of exome sequence in 604 trios for recessive genotypes in schizophrenia

Genetic associations involving both rare and common alleles have been reported for schizophrenia but there have been no systematic scans for rare recessive genotypes using fully phased trio data. Here, we use exome sequencing in 604 schizophrenia proband–parent trios to investigate the role of recessive (homozygous or compound heterozygous) nonsynonymous genotypes in the disorder. The burden of recessive genotypes was not significantly increased in probands at either a genome-wide level or in any individual gene after adjustment for multiple testing. At a system level, probands had an excess of nonsynonymous compound heterozygous genotypes (minor allele frequency, MAF ⩽1%) in voltage-gated sodium channels (VGSCs; eight in probands and none in parents, P=1.5 × 10⁻⁴). Previous findings of multiple de novo loss-of-function mutations in this gene family, particularly SCN2A, in autism and intellectual disability provide biological and genetic plausibility for this finding. Pointing further to the involvement of VGSCs in schizophrenia, we found that these genes were enriched for nonsynonymous mutations (MAF ⩽0.1%) in cases genotyped using an exome array, (5585 schizophrenia cases and 8103 controls), and that in the trios data, synaptic proteins interacting with VGSCs were also enriched for both compound heterozygosity (P=0.018) and de novo mutations (P=0.04). However, we were unable to replicate the specific association with compound heterozygosity at VGSCs in an independent sample of Taiwanese schizophrenia trios (N=614). We conclude that recessive genotypes do not appear to make a substantial contribution to schizophrenia at a genome-wide level. Although multiple lines of evidence, including several from this study, suggest that rare mutations in VGSCs contribute to the disorder, in the absence of replication of the original findings regarding compound heterozygosity, this conclusion requires evaluation in a larger sample of trios.     

Plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism, coronary thrombosis, and myocardial infarction in middle-aged Finnish men who died suddenly

High plasminogen activator inhibitor-1 (PAI-1) plasma levels increase future risk of myocardial infarction (MI). The 4G allele of the 4G/5G polymorphism of the PAI-1 gene has been associated with increased plasma levels of PAI-1. The association of the PAI-1 polymorphism with coronary narrowings, coronary thrombosis and myocardial infarction (MI) was studied in a prospective autopsy series of 300 middle-aged Caucasian Finnish men (33 to 69 yrs) suffering sudden out-of-hospital death (Helsinki Sudden Death Study). The 4G allele was found in 76.8% of men with sudden cardiac death (SCD) compared to 67.5% in men who died accidentally and 63.2% in men who died of other diseases (p = 0.08 and p = 0.055, respectively). Men possessing the 4G allele had more often acute MI (OR 3.5; p <0.05) and coronary thrombosis (OR 5.5. p = 0.01) compared to 5G homozygotes. 5G homozygotes, comprising one third of the men in our study, seem to be at a decreased risk of thrombosis, whereas carriers of the common 4G allele have an increased risk of thrombosis, AMI and possibly SCD compared to 5G homozygotes.     

Analysis of the Na,K-ATPase alpha- and beta-subunit expression profiles of bladder cancer using tissue microarrays

BACKGROUND: The purpose of this study was to determine the clinical significance of Na,K-ATPase alpha- and beta-subunit expression in a histopathologically well-characterized group of patients representing a wide spectrum of tumor grades and disease stages with transitional cell carcinomas (TCC). METHODS: Na,K-ATPase alpha- and beta-subunit protein expression patterns were analyzed using immunohistochemistry on urothelial cancer tissue microarrays (TMA) of 146 patients diagnosed with urothelial carcinoma. For each subunit, the maximum staining intensity and the percentage of positive cells staining at the maximal intensity were analyzed. RESULTS: Compared with the benign fields, the mean protein expression for both Na,K-ATPase alpha- and beta-subunits were found to be decreased overall in in situ and invasive tumors, as well as in tumor-adjacent dysplastic fields. When Na,K-ATPase alpha- and beta-subunit expression levels were dichotomized into distinct groups, they were both found to be significant predictors of recurrence risk in multivariate logistic regression analysis (P = 0.0062, odds ratio [OR] = 2.6 and P = 0.013, OR = 0.43, for Na,K-ATPase alpha- and beta-subunits, respectively). The authors also found that patients with high alpha- and low beta-subunit expression had a high risk for early recurrence, whereas patients with a low alpha- and high beta-subunit expression had a significantly longer median recurrence-free time (17 months and 125 months, respectively, log rank statistics P = 0.0005). CONCLUSIONS: The results suggested that Na,K-ATPase alpha- and beta-subunit expression levels may be useful predictors of clinical outcomes such as recurrence-free time of bladder cancer patients.     

A novel missense ATP1A2 mutation in a Finnish family with familial hemiplegic migraine type 2

Familial hemiplegic migraine (FHM), a rare autosomal dominant subtype of migraine with aura, has been linked to two chromosomal loci, 19p13 and 1q23. Mutations in the Na⁺,K⁺-ATPase 2 subunit gene, ATP1A2, on 1q23 have recently been shown to cause familial hemiplegic migraine type 2 (FHM2). We sequenced the coding regions of this gene in a Finnish chromosome 1q23-linked FHM family with associated symptoms such as coma and identified a novel A1033G mutation in exon 9. This mutation results in a threonine-to-alanine substitution at codon 345. This residue is located in a highly conserved N-terminal region of the M4–5 loop of the Na⁺,K⁺-ATPase. Furthermore, the T345A mutation co-segregated with the disorder in our family and was not present in 132 healthy Finnish control individuals. For these reasons it is most likely the FHM-causing mutation in this family.     

Geographical structure and differential natural selection among North European populations

Population structure can provide novel insight into the human past, and recognizing and correcting for such stratification is a practical concern in gene mapping by many association methodologies. We investigate these patterns, primarily through principal component (PC) analysis of whole genome SNP polymorphism, in 2099 individuals from populations of Northern European origin (Ireland, United Kingdom, Netherlands, Denmark, Sweden, Finland, Australia, and HapMap European-American). The major trends (PC1 and PC2) demonstrate an ability to detect geographic substructure, even over a small area like the British Isles, and this information can then be applied to finely dissect the ancestry of the European-Australian and European-American samples. They simultaneously point to the importance of considering population stratification in what might be considered a small homogeneous region. There is evidence from F_ST-based analysis of genic and nongenic SNPs that differential positive selection has operated across these populations despite their short divergence time and relatively similar geographic and environmental range. The pressure appears to have been focused on genes involved in immunity, perhaps reflecting response to infectious disease epidemic. Such an event may explain a striking selective sweep centered on the rs2508049-G allele, close to the HLA-G gene on chromosome 6. Evidence of the sweep extends over a 8-Mb/3.5-cM region. Overall, the results illustrate the power of dense genotype and sample data to explore regional population variation, the events that have crafted it, and their implications in both explaining disease prevalence and mapping these genes by association.Patterns of genetic variation within and between human populations have long provided novel insights into the origin and history of different groups. The advent of whole genome association (WGA) mapping has also highlighted the practical importance of identifying and understanding these patterns. A mismatch in the ancestry of individuals in a simple case/control association paradigm can lead to false positives and/or reduced power to detect associations.Studies of population-level whole genome (WG) polymorphism were initially restricted to the International HapMap populations (Yoruban, Japanese, Chinese, and European-Americans) but provided valuable information on intercontinental variation across the human genome, including structural variation, recombination, and selection (International HapMap Consortium 2005, 2007). The whole genome approach has now begun to be applied to more nuanced intracontinental variation within Europe. First generation studies using European-Americans or small numbers of in situ Europeans (but with relatively few markers) quickly identified a clear North–South split in the continent''s population and hinted at further structure (Seldin et al. 2006; Bauchet et al. 2007; Price et al. 2008; Seldin and Price 2008; Tian et al. 2008). Analysis of WG variation in larger numbers of individuals sampled in situ from multiple European populations has recently extended these findings. Using principal component analysis (PCA) of up to ≈300,000 SNPs, they have shown a remarkable correlation of an individual''s position in genetic space to their geographic origin (Heath et al. 2008; Lao et al. 2008; Novembre et al. 2008).We continue this progression by exploring subcontinental WG (300K) variation in 2099 individuals from six Northern European populations (Ireland, United Kingdom, Netherlands, Sweden, Denmark, and Finland), as well as two descendent New World populations (European-Australians and the European-American HapMap sample). The data demonstrate and confirm an ability to dissect regional to subregional geographic structure and also point to the discernable impact of differential natural selection on the recently diverged Northern European populations. Both of these observations have important present-day consequences in explaining disease incidence and in mapping complex traits through association methods.     

CD14 and TNfa promoter polymorphisms in patients with acute arthritis. Special reference to development of chronic spondyloarthropathy

OBJECTIVE: To examine CD14 and TNFalpha gene polymorphisms in early arthritis in relation to clinical outcome. METHODS: We studied 141 Caucasians who had had early arthritis 10 to 38 years earlier. We analysed CD14 (-159) and TNFalpha (-238, -308, -376) polymorphisms using a novel cycle minisequencing method. DNA pools from 370 Caucasian blood donors served as controls. RESULTS: CD14 (-159)C-->T allele frequencies were comparable among patients and controls (39% vs 40%). Fifty men and 42 women had recovered while 24 men and six women had chronic spondyloarthropathy (SpA). Mutant T allele frequency was higher in the chronic SpA group than in the recovered group in women (75% vs 32%, relative risk 1.3, 95% confidence limit 1.1 to 1.6, P = 0.011), but not in men (38% vs 44%). All female patients with chronic SpA had CD14 (-159)T allele and none had a possibly protective TNFalpha (-308)G-->A allele. CONCLUSIONS: Possession of CD14 (-159)T allele does not increase risk of ReA but may increase susceptibility of female patients to development of chronic SpA.     

Multiallelic polymorphism of the cartilage collagen gene: no association with osteoarthrosis.

OBJECTIVES--To determine whether any of the type II collagen alleles are associated with generalised osteoarthrosis or osteoarthrosis of the finger joints in the genetically isolated Finnish population. METHODS--Two patient cohorts with evidence for only primary osteoarthrosis and a cohort of healthy control subjects were selected from the Helsinki University Central Hospital and the Rheumatism Foundation Hospital in Finland. Forty one patients with primary generalised osteoarthrosis, 49 patients with osteoarthrosis of the finger joints, and 48 control subjects were included. Two markers of the type II collagen gene, a PvuII polymorphism and a VNTR polymorphism, were analysed from each subject. RESULTS--Four different alleles of the VNTR marker were observed and the relative risks associated with the different VNTR alleles varied between 0.39 and 1.24 among the patients with generalised osteoarthrosis and between 0.67 and 2.33 among the patients with osteoarthrosis of the finger joints. The PvuII polymorphism detected two different alleles and the associated relative risks were 0.82 and 1.82 for the patients with generalised osteoarthrosis, and 1.04 and 0.96 for the patients with osteoarthrosis of the finger joints. CONCLUSIONS--A major predisposing allele of the type II collagen gene as the causative factor for osteoarthrosis could be excluded in this population. A spectrum of mutations associated with different alleles of this gene could not be excluded, however. Further, these two forms of cartilage disease can be caused by gene defects with reduced penetrance and the effect of such an allele is easily masked under the high frequency of normal alleles.