Association between family history and mismatch repair in colorectal cancer.

BACKGROUND AND AIMS: Germline mutations in mismatch repair (MMR) genes cause a greatly increased risk of cancer of the gastrointestinal and female reproductive tracts (hereditary non-polyposis colorectal cancer (HNPCC)). Loss of MMR expression is common in colorectal cancer (CRC) overall. Such loss is assumed to be acquired predominantly, although a population of CRC cases will include individuals with unrecognised MMR mutations. This study examines the association between MMR gene expression and family history of cancer among the CRC population. METHODS: Individuals with CRC were identified from two well characterised populations: (1) consecutive hospital patients (n = 644) and (2) a population based cases series (n = 249). CRC was examined for expression of hMLH1 and hMSH2 using immunohistochemistry, and expression was related to family history using logistic regression. RESULTS: hMLH1 and hMSH2 expression was assessed in 732 CRCs with 8% showing loss of expression. No association was seen overall for hMLH1 or hMSH2 expression and family history of CRC. Loss of hMSH2 was predicted by family history of extracolonic cancer (odds ratio (OR) 5.78 (95% confidence interval (CI) 0.95-35.18)) and family history suggestive of HNPCC (OR 27.84 (95% CI 4.37-177.56)). Loss of hMLH1 was not predicted by family history of extracolonic cancer or a family history suggestive of HNPCC but was for a family history of at least two affected relatives (OR 4.88 (95% CI 1.25-19.03)). CONCLUSIONS: Individuals with hMSH2 deficient CRC in the general population exhibit a family history and other characteristics suggestive of HNPCC, and may carry germline MMR mutations. Loss of hMLH1 is only associated with a strong family history of extracolonic cancer at older ages, suggesting a novel mechanism of susceptibility.

Somatic mutations of KIT in familial testicular germ cell tumours.

Somatic mutations of the KIT gene have been reported in mast cell diseases and gastrointestinal stromal tumours. Recently, they have also been found in mediastinal and testicular germ cell tumours (TGCTs), particularly in cases with bilateral disease. We screened the KIT coding sequence (except exon 1) for germline mutations in 240 pedigrees with two or more cases of TGCT. No germline mutations were found. Exons 10, 11 and 17 of KIT were examined for somatic mutations in 123 TGCT from 93 multiple-case testicular cancer families. Five somatic mutations were identified; four were missense amino-acid substitutions in exon 17 and one was a 12 bp in-frame deletion in exon 11. Two of seven TGCT from cases with bilateral disease carried KIT mutations compared with three out of 116 unilateral cases (P=0.026). The results indicate that somatic KIT mutations are implicated in the development of a minority of familial as well as sporadic TGCT. They also lend support to the hypothesis that KIT mutations primarily take place during embryogenesis such that primordial germ cells with KIT mutations are distributed to both testes.

Segregation analysis comparing liability and quantitative trait models for hypertension using the Genetic Analysis Workshop 13 simulated data.

Discrete (qualitative) data segregation analysis may be performed assuming the liability model, which involves an underlying normally distributed quantitative phenotype. The appropriateness of the liability model for complex traits is unclear. The Genetic Analysis Workshop 13 simulated data provides measures on systolic blood pressure, a highly complex trait, which may be dichotomized into a discrete trait (hypertension). We perform segregation analysis under the liability model of hypertensive status as a qualitative trait and compare this with results using systolic blood pressure as a quantitative trait (without prior knowledge at that stage of the true underlying simulation model) using 1050 pedigrees ascertained from four replicates on the basis of at least one affected member. Both analyses identify models with major genes and polygenic components to explain the family aggregation of systolic blood pressure. Neither of the methods estimates the true parameters well (as the true model is considerably more complicated than those considered for the analysis), but both identified the most complicated model evaluated as the preferred model. Segregation analysis of complex diseases using relatively simple models is unlikely to provide accurate parameter estimates but is able to indicate major gene and/or polygenic components in familial aggregation of complex diseases.

Using single nucleotide polymorphisms to investigate association between a candidate gene and disease.

A range of study designs, using unrelated or family controls, were used to investigate the pattern of association with disease of single nucleotide polymorphisms (SNPs) within candidate gene 1 (simulated data). Strong evidence of disease association at the functional locus was detected using all study designs, and in the "general" but not the "isolated" population the functional polymorphism displayed considerably higher association than surrounding SNPs. There was much variation in the strength of association of SNPs with disease, up to 70% of which was explained by SNP allele frequency and distance from the functional polymorphism. Some common polymorphisms very close to the functional locus however showed no association with disease. Analysis of short haplotypes of SNPs reduced but did not totally remove this feature.

Localization to Xq27 of a susceptibility gene for testicular germ-cell tumours.

Testicular germ-cell tumours (TGCT) affect 1 in 500 men and are the most common cancer in males aged 15-40 in Western European populations. The incidence of TGCT has risen dramatically over the last century. Known risk factors for TGCT include a history of undescended testis (UDT), testicular dysgenesis, infertility, previously diagnosed TGCT (ref. 7) and a family history of the disease. Brothers of men with TGCT have an 8-10-fold risk of developing TGCT (refs 8,9), whereas the relative risk to fathers and sons is fourfold (ref. 9). This familial relative risk is much higher than that for most other types of cancer. We have collected samples from 134 families with two or more cases of TGCT, 87 of which are affected sibpairs. A genome-wide linkage search yielded a heterogeneity lod (hlod) score of 2.01 on chromosome Xq27 using all families compatible with X inheritance. We obtained a hlod score of 4.7 from families with at least one bilateral case, corresponding to a genome-wide significance level of P=0.034. The proportion of families with UDT linked to this locus was 73% compared with 26% of families without UDT (P=0.03). Our results provide evidence for a TGCT susceptibility gene on chromosome Xq27 that may also predispose to UDT.

Analysis of simulated data: evidence for genetic and environmental effects.

We approached the simulation as though it were an international study with similar but not identical information being collected from different populations. In keeping with this we analyzed one replicate from each population. Initially we examined the risk of disease in relatives of cases to determine whether the disease appeared to be "more genetic" in one population than in the others and we examined the evidence for environmental risk factors in each population. Nonparametric linkage analysis and transmission/disequilibrium testing (TDT) were used to search for loci linked to the disease in each population. Using these methods we identified several candidate regions for a susceptibility gene which on examination of the answers are explicable in terms of the underlying model.

Linkage studies of non-syndromic recessive deafness (NSRD) in a family originating from the Mirpur region of Pakistan maps DFNB1 centromeric to D13S175.

Autosomal recessive non-syndromal hearing impairment (NSRD) is genetically heterogeneous. Five loci have been identified to date which map to chromosomes 13 (DFNB1), 11 (DFNB2), 17 (DFNB3), 7 (DFNB4) and 14 (DFBN5). We report definite linkage of NSRD to the locus DFNB1 in a single family of 27 families studied of Pakistani origin. Haplotype analysis of markers in the pericentromeric region of chromosome 13q revealed a recombination event which maps DFNB1 proximal to the marker D13S175 and in the vicinity of D13S143.

Genetic linkage analysis in familial breast and ovarian cancer: results from 214 families. The Breast Cancer Linkage Consortium.

Breast cancer is known to have an inherited component, consistent in some families with autosomal dominant inheritance; in such families the disease often occurs in association with ovarian cancer. Previous genetic linkage studies have established that in some such families disease occurrence is linked to markers on chromosome 17q. This paper reports the results of a collaborative linkage study involving 214 breast cancer families, including 57 breast-ovarian cancer families; this represents almost all the known families with 17q linkage data. Six markers on 17q, spanning approximately 30 cM, were typed in the families. The aims of the study were to define more precisely the localization of the disease gene, the extent of genetic heterogeneity and the characteristics of linked families and to estimate the penetrance of the 17q gene. Under the assumption of no genetic heterogeneity, the strongest linkage evidence was obtained with D17S588 (maximum LOD score [Zmax] = 21.68 at female recombination fraction [theta f] = .13) and D17S579 (Zmax = 13.02 at theta f = .16). Multipoint linkage analysis allowing for genetic heterogeneity provided evidence that the predisposing gene lies between the markers D17S588 and D17S250, an interval whose genetic length is estimated to be 8.3 cM in males and 18.0 cM in females. This position was supported over other intervals by odds of 66:1. The location of the gene with respect to D17S579 could not be determined unequivocally. Under the genetic model used in the analysis, the best estimate of the proportion of linked breast-ovarian cancer families was 1.0 (lower LOD-1 limit 0.79). In contrast, there was significant evidence of genetic heterogeneity among the families without ovarian cancer, with an estimated 45% being linked. These results suggest that a gene(s) on chromosome 17q accounts for the majority of families in which both early-onset breast cancer and ovarian cancer occur but that other genes predisposing to breast cancer exist. By examining the fit of the linkage data to different penetrance functions, the cumulative risk associated with the 17q gene was estimated to be 59% by age 50 years and 82% by age 70 years. The corresponding estimates for the breast-ovary families were 67% and 76%, and those for the families without ovarian cancer were 49% and 90%; these penetrance functions did not differ significantly from one another.

Linkage analysis of early-onset breast and ovarian cancer families, with markers on the long arm of chromosome 17.

We have conducted linkage analysis in 16 breast cancer families, 13 of which are classified as site-specific breast cancer families and 3 of which are classified as breast-ovary families. Linkage analysis has largely focused on a single extended breast-ovary family. Analysis of all families combined shows significant evidence for linkage to 17q (LOD = 3.63 at theta = .0, for linkage to NME1), confirming the observations of Hall et al. and Narod et al. Many families were consistent with linkage, but their limited size and informativeness precluded confirmation of linkage. A putative recombinant in a breast-ovary family suggests that BRCA1 is distal to D17S250.

Sweat lead levels in persons with high blood lead levels: experimental elevation of blood lead by ingestion of lead chloride.

Blood lead levels were experimentally elevated in two subjects by ingestion of single oral doses of lead as lead chloride. Serial samples of blood, urine and sweat were collected subsequently. Sweat samples were collected in polythene armbags while subjects cycled on a bicycle ergometer in a hot chamber. In spite of increases in blood and urinary lead levels, no increases in sweat lead levels were recorded. Possible reasons for this observation are discussed.

Lead in sweat and its relationship to salivary and urinary levels in normal healthy subjects.

Sweat was collected from the arms of 24 normal healthy subjects while they sat in a hot chamber. Blood, urine and saliva samples were also collected. These were analyzed for lead by atomic absorption spectrophotometry. Sweat lead levels recorded in this study are lower than those previously reported. Subjects with mean blood lead levels of 8.62 micrograms dl-1 (range 6-13.6) had mean sweat levels of 5.2 micrograms l-1 (range 1.5-13.0), approximately 25% of their urinary levels. Although salivary lead levels with a mean of 4.8 micrograms l-1 (range 2.5-10) are comparable to sweat levels, their relationship to blood lead levels is poor (r = -0.186 compared with r values of 0.7208 and 0.234 for sweat and urinary levels, respectively).

Epidemiology of shingles.

One thousand and nineteen patients with acute varicella zoster viral infection were referred to the physiotherapy department for treatment between 1978 and 1986. Sixty per cent were women and 40% were men with a mean age of 58 years (range 9-96 years). The prevalence varied between 1.3 and 1.6 per 1000 per annum. The left side was affected in 52% while the right was affected in 48%. The thoracic dermatomes were the most commonly affected (56%) followed by cervical (17%), lumbar (10%), sacral (5%), and the trigeminal nerve was infected in 12%. There was a significant seasonal (P less than 0.001) variation in the prevalence of acute varicella zoster virus infection, most common in the summer and least common in the spring. There was no clustering in time and space so that it is unlikely that the varicella zoster virus is infective or that re-exposure to the virus causes reactivation of the latent virus.

Lipopolysaccharide-free Escherichia coli OmpF and Pseudomonas aeruginosa protein P porins are functionally active in lipid bilayer membranes.

Escherichia coli porin OmpF and Pseudomonas aeruginosa porin protein P were eluted from sodium dodecyl sulfate-polyacrylamide gels. The resultant porin preparations were found to be devoid of detectable lipopolysaccharide (LPS) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining for LPS, direct enzyme-linked immunosorbent assays with LPS-specific monoclonal antibodies, and 2-keto-3-deoxyoctulosonic acid assays. The average conductances, ionic selectivities and incorporation rates of the electroeluted porins were identical to those of their conventionally purified counterparts. These data suggest that LPS is not required per se for porin function.

Outer membrane protein NmpC of Escherichia coli: pore-forming properties in black lipid bilayers.

The purified NmpC outer membrane protein from Escherichia coli, when incorporated into planar lipid bilayers, gave rise to channels with a single-channel conductance of 1.8 nS in 1 M KCl. This suggests that the NmpC protein is a porin.

Monoclonal antibodies specific for Escherichia coli J5 lipopolysaccharide: cross-reaction with other gram-negative bacterial species.

Four monoclonal antibodies against Escherichia coli J5 were studied. Each of these monoclonal antibodies reacted with purified lipopolysaccharides from E. coli J5, the deep rough mutant Salmonella minnesota Re595, Agrobacterium tumefaciens, and Pseudomonas aeruginosa PAO1 as well as with the purified lipid A of P. aeruginosa. Enzyme-linked immunosorbent assays using the outer membranes from a variety of gram-negative bacteria demonstrated that these lipid A-specific monoclonal antibodies interacted with between 84 and 97% of the gram-negative bacterial species tested. One of the monoclonal antibodies, 5E4, was shown to interact with 34 of the 35 outer membrane or lipopolysaccharide antigens tested. Immunoenzymatic staining of Western electrophoretic blots of separated P. aeruginosa outer membrane components was used to demonstrate that antibody 5E4 interacted with a similar fast-migrating band, corresponding to rough lipopolysaccharide, from all 17 serotype strains and all 14 clinical isolates of P. aeruginosa. Similarly, iodinated goat anti-mouse immunoglobulin was used to detect the binding of monoclonal antibody 8A1 to a fast-migrating band on Western electrophoretic blots of purified lipopolysaccharides from Klebsiella pneumoniae and both smooth and rough strains of E. coli, Salmonella typhimurium, and S. minnesota. These results suggest considerable conservation of single antigenic sites in the lipid A of gram-negative bacteria.

Measurement of the clothing ventilation index.

In order to achieve thermal comfort while wearing protective clothing, heat loss from the body by convection and by the evaporation of sweat must be readily controlled by the wearer's thermoregulatory system. This can only be achieved if air is flowing through the clothing micro-environment in sufficient quantity to remove sensible and insensible heat as required. The volume flow of air through the clothing assembly is therefore an important determinant of thermal comfort. This paper describes a new procedure for estimating under working conditions, the volume of air flowing through the micro-environment. The method is based on two techniques: the first gives a measure of the volume of the micro-environment; the other uses a trace gas to measure the rate of air exchange. Algebraic combination of the results enables the air exchange characteristics of a garment to be described in terms of a Ventilation Index. It is proposed that this index be used to describe the performance of protective clothing assemblies.