Uncovering Hereditary Tumor Syndromes: Emerging Role of Surgical Pathology

With the increased use of modern next generation sequencing technologies in routine molecular pathology practice, the proportion of cancer cases with a definite or probable hereditary background seems to be steadily increasing. Currently, it is assumed that ≥10% of all malignancies develop in the setting of germline predisposition. Diagnosis and recognition of cancer predisposition syndromes relies not rarely on distinctive histopathological features that proved to be highly valuable and reproducible in uncovering those diseases that would otherwise have gone undetected by clinicians as being hereditary in nature. This is especially true in case of new mutations without suspicious family history. Example of such entities are fumarate hydratase-deficient renal cell carcinoma (RCC), succinate dehydrogenase-deficient RCC, hereditary gastrointestinal stromal tumor syndromes and many other diseases. It is remarkable that many of these inherited cancer syndromes do present as unifocal disease with highly variable age of onset so that many of them are misinterpreted as sporadic on clinical grounds. Availability of specialized cancer screening programs and disease-specific follow-up schemes for several hereditary cancer syndromes encourages the recognition of such disorders, so that "at risk patients" can be enrolled in such programs for early detection and timely intervention/ treatment of these malignancies which are in the majority of cases aggressive. In several conditions, as in familial adenomatous polyposis coli (FAP), well established prophylactic surgical interventions may be adopted to prevent the disease manifestations, highlighting the importance of the timely recognition of these potentially life-limiting neoplasms. In this review, the clinicopathological, demographic and histological features that are considered highly suggestive of a hereditary basis of "a neoplasm under consideration" are highlighted and discussed briefly. The details of some of these entities are in addition dealt with in reviews devoted to them in this special issue     

High-sensitivity C-reactive protein,low-grade systemic inflammation and type 2 diabetes mellitus: A two-sample Mendelian randomization study

Background and aims

The role of inflammation in type 2 diabetes mellitus (T2D) remains unclear. We investigated the associations of high sensitivity C-reactive protein (hsCRP) concentration with T2D and glycemic traits using two-sample Mendelian Randomization.

Iron Status and NAFLD among European Populations: A Bidirectional Two-Sample Mendelian Randomization Study

Background and aim: Previous observational studies have suggested a paradoxical relationship between iron status and the risk of non-alcoholic fatty liver disease (NAFLD). Observed associations in these epidemiological studies fail to show sequential temporality and suffer from problems of confounding. Therefore, we performed a bidirectional two-sample Mendelian randomization (MR) to evaluate the relationship between serum iron status and NAFLD. Methods: The inverse weighted method (IVW) meta-analysis with the fixed-effect model was the main method to estimate the relationship between iron status, including serum ferritin, iron, transferrin saturation (TSAT) and total iron-binding capacity (TIBC), and NAFLD. Weighted median, penalized weighted median, and MR Robust Adjusted Profile Score (MR RAPS) methods were used as additional analyses. Sensitivity analyses were performed with Cochran’s Q test, MR–Egger regression, Steiger filtering, and the MR PRESSO test. Results: Iron status, including serum ferritin, iron, and TSAT, was associated with an increased risk of NAFLD (odds ratio (OR) (95% confidence interval (CI)): 1.25 (1.06, 1.48); 1.24 (1.05, 1.46), 1.16 (1.02, 1.31), respectively). In contrast, minimal effects of NAFLD on serum ferritin, iron, TSAT, and TIBC were observed (OR (95% CI): 1.01 (1.00, 1.02), 1.01 (1.00, 1.02), 1.03 (1.01, 1.05), 1.03 (1.01, 1.05), respectively). Conclusions: Our findings corroborated the causal associations between serum ferritin, iron, TSAT, and NAFLD, which might suggest the potential benefits of iron-related therapy. In addition, NAFLD might, in turn, slightly affect iron homeostasis indicated as serum ferritin, iron, TSAT, and TIBC, but this needs to be further confirmed.     

Role of Inflammatory Factors in Mediating the Effect of Lipids on Nonalcoholic Fatty Liver Disease: A Two-Step,Multivariable Mendelian Randomization Study

Aims/hypothesis: 20–80% of Nonalcoholic Fatty Liver Disease (NAFLD) have been observed to have dyslipidemia. Nevertheless, the probable mechanism of dyslipidemia’s effect on NAFLD remains unclear. Mendelian randomization (MR) was utilized to investigate the relationship between lipids, inflammatory factors, and NAFLD; and also, to determine the proportion mediated by interleukin-17(IL-17) and interleukin-1β(IL-1β) for the effect between lipids and NAFLD. Methods: Summary statistics of traits were obtained from the latest and largest genome-wide association study (GWAS). The UK Biobank provided a summary of lipid statistics, which comprised up to 500,000 participants of European descent. And NAFLD GWAS summary statistics were obtained from the FinnGen Biobank which included a total sample size of 218,792 participants of European ancestry. In order to gain an overall picture of how lipids affect NAFLD, MR with two samples was carried out. Multivariable MR determined lipids direct effects on NAFLD after adjusting for inflammatory factors, namely IL-1β, interleukin-6(IL-6), interleukin-16(IL-16), IL-17, and interleukin-18(IL-18); those lipids comprise HDL cholesterol (HDL-C), LDL cholesterol (LDL-C), triglycerides (TGs), apolipoprotein A1 (ApoA1), and apolipoprotein B (ApoB). For the purpose of determining the MR impact, an inverse variance weighted (IVW) meta-analysis of each Wald Ratio was carried out, while other methods were also performed for sensitivity analysis. Results: We discovered a positive association between genetically predicted TGs levels and a 45.5% elevated risk of NAFLD, while genetically predicted IL-1β [(IVW: OR 1.315 (1.060–1.630), p = 0.012) and IL-17 [(IVW: OR 1.468 (1.035–2.082), p = 0.032] were positively associated with 31.5% and 46.8% increased risk of NAFLD, respectively. Moreover, TG was positively associated with 10.5% increased risk of IL-1β and 17.3% increased risk of IL-17. The proportion mediated by IL-17 and IL-1β respectively and both was 2.6%, 3.1%, 14.1%. Conclusion: Genetically predicted TGs, IL-1β, and IL-17 were positively associated with increased risk of NAFLD, with evidence that IL-1β and IL-17 mediated TGs effect upon NAFLD risk. It indicated that early diet management, weight management, lipid-lowering and anti-inflammatory treatment should be carried out for patients with hyperlipidemia to prevent the NAFLD.     

The effect of unbalanced randomization on the progressively censored savage test

Equal allocation of patients to treatment in a randomized clinical trial may have disadvantages ethically if the new treatment is believed to be at least as beneficial as the standard treatment. Others have considered, in a non-sequential setting, unbalanced randomized designs which allocate fewer patients to the potentially inferior standard treatment. This paper examines unbalanced randomized designs in a sequential comparison of two exponential survival distributions using the progressively censored Savage test. The results reveal no substantial sacrifice in asymptotic power or early stopping properties.     

Utility of the Randomization Test and Importance of Nonstatis-tical Inference in Experimental Teratology

The implausibility of random sampling assumption in experimental teratology is pointed out. It is emphasized that nonstatistical inference remains a standard scientific approach, in spite of widespread use of many statistical tests. The randomization test can be introduced to experimental teratologjsts as an alternative to conventional statistical procedures for nonrandom sampling data. A program list for the randomization test written in BASIC for microcompter is given.     

ADVANTAGES OF PERMUTATION (RANDOMIZATION) TESTS IN CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY

1. The statistical procedures that are used most commonly in clinical and experimental pharmacology and physiology are designed to test for differences between two means. 2. The classical procedures for detecting such differences are those in which, under the population model of inference, the test statistic is referred to the t- or F-distributions. The validity of statistical inferences from these tests depends on a number of assumptions. Foremost among these is that the experimental groups have been constructed by taking random samples from defined populations. The statistical inferences then apply to the sampled populations. 3. In biomedical research this sampling process is seldom followed. Instead, samples are usually acquired by non-random selection, and are then divided by randomization into experimental groups. This being the case, it is theoretically invalid to use the classical t- or F-tests to analyse the experimental results. 4. The validity of inferences from the classical tests also depends on other assumptions, such as that the sampled populations are normal in form and of equal variance. It is difficult to be certain that these assumptions are fulfilled when group sizes are small, as they usually are in pharmacology and physiology. Breach of them, especially if the groups are unequal in size, can lead to serious statistical errors. 5. Exact permutation tests are designed to make statistical inferences under the randomization model. These conclusions apply only to the results of experiments actually performed. By permuting the statistic of interest, such as the difference between arithmetic means, geometric means, medians, mid-ranges or mean-ranks of randomized groups of observations, the probability is calculated that the observed difference or a more extreme one could have occurred by chance. This inferential process is consistent with the way most biomedical experiments are designed and conducted. 6. Exact permutation tests, or sampled permutation tests based on Monte Carlo random sampling of all possible permutations, can now be performed on personal computers. They are commended to biomedical investigators as being superior to the classical tests for analysing their experimental results when the central tendencies of two independent groups, or of two sets of measurements on the same group, are compared. 7. When there is doubt that the assumptions for t-tests are satisfied, investigators sometimes use non-parametric rank-order procedures such as the Wilcoxon-Mann-Whitney rank-sum test for independent groups or the Wilcoxon signed rank-sum test for paired observations. These procedures are permutation tests for differences between mean-ranks and are invalid tests for differences between medians or means. 8. When experiments are complex and based on randomization rather than random sampling, as in randomized block, Latin square, factorial or split-unit designs, analysis of these by permutation tests is to be preferred on theoretical grounds, though the necessary computer software is not readily available.     

Lack of association between the MTHFR (C677T) polymorphism and atopic disease

Background: Impaired folate metabolism has been suggested as a potential risk factor for the development of asthma and atopic disease. However, there have been conflicting reports on the potential association between atopic disease and a common polymorphism of the methylene‐tetrahydrofolate reductase (MTHFR)‐gene, a well‐known marker of impaired folate metabolism. Objectives: The aim of this study was to investigate the association between the MTHFR (C677T) polymorphism and different outcome variables of asthma and atopic disease. Methods: This study was a population‐based study of 1189 participants aged 15–77 years living in Copenhagen, the Capital of Denmark. Examinations included measurements of specific IgE and skin prick tests against inhalant allergens, metacholine bronchial hyper‐reactivity, and serum eosinophilic cationic protein, and a self‐administered questionnaire about diagnoses and symptoms of allergy and asthma. In addition, participants were genotyped for the MTHFR (C677T) polymorphism. Results: None of the examined outcomes were significantly associated with the MTHFR (C677T) polymorphism. Conclusions: The results of this study using detailed objective markers of atopic disease do not support the hypothesis that impaired folate metabolism as reflected by the MTHFR genotype is involved in the development of atopic disease. Please cite this paper as: Thuesen BH, Husemoen LLN, Fenger M and Linneberg A. Lack of association between the MTHFR (C677T) polymorphism and atopic disease. The Clinical Respiratory Journal 2009; 3: 102–108.     

New insights into tetrahydrobiopterin pharmacodynamics from Pah, a mouse model for compound heterozygous tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency

Phenylketonuria (PKU), an autosomal recessive disease with phenylalanine hydroxylase (PAH) deficiency, was recently shown to be a protein misfolding disease with loss-of-function. It can be treated by oral application of the natural PAH cofactor tetrahydrobiopterin (BH₄) that acts as a pharmacological chaperone and rescues enzyme function in vivo. Here we identified Pah^enu1/2 bearing a mild and a severe mutation (V106A/F363S) as a new mouse model for compound heterozygous mild PKU. Although BH₄ treatment has become established in clinical routine, there is substantial lack of knowledge with regard to BH₄ pharmacodynamics and the effect of the genotype on the response to treatment with the natural cofactor. To address these questions we applied an elaborate methodological setup analyzing: (i) blood phenylalanine elimination, (ii) blood phenylalanine/tyrosine ratios, and (iii) kinetics of in vivo phenylalanine oxidation using ¹³C-phenylalanine breath tests. We compared pharmacodynamics in wild-type, Pah^enu1/1, and Pah^enu1/2 mice and observed crucial differences in terms of effect size as well as effect kinetics and dose response. Results from in vivo experiments were substantiated in vitro after overexpression of wild-type, V106A, and F263S in COS-7 cells. Pharmacokinetics did not differ between Pah^enu1/1 and Pah^enu1/2 indicating that the differences in pharmacodynamics were not induced by divergent pharmacokinetic behavior of BH₄. In conclusion, our findings show a significant impact of the genotype on the response to BH₄ in PAH deficient mice. This may lead to important consequences concerning the diagnostic and therapeutic management of patients with PAH deficiency underscoring the need for individualized procedures addressing pharmacodynamic aspects.