Universal fluctuations in correlated systems

The probability density function (PDF) of a global measure in a large class of highly correlated systems has been suggested to be of the same functional form. Here, we identify the analytical form of the PDF of one such measure, the order parameter in the low temperature phase of the 2D XY model. We demonstrate that this function describes the fluctuations of global quantities in other correlated equilibrium and nonequilibrium systems. These include a coupled rotor model, Ising and percolation models, models of forest fires, sandpiles, avalanches, and granular media in a self-organized critical state. We discuss the relationship with both Gaussian and extremal statistics.

A de novo frameshift in HNRNPK causing a Kabuki-like syndrome with nodular heterotopia

Kabuki syndrome is a heterogeneous condition characterized by distinctive facial features, intellectual disability, growth retardation, skeletal abnormalities and a range of organ malformations. Although at least two major causative genes have been identified, these do not explain all cases. Here we describe a patient with a complex Kabuki-like syndrome that included nodular heterotopia, in whom testing for several single-gene disorders had proved negative. Exome sequencing uncovered a de novo c.931_932insTT variant in HNRNPK (heterogeneous nuclear ribonucleoprotein K). Although this variant was identified in March 2012, its clinical relevance could only be confirmed following the August 2015 publication of two cases with HNRNPK mutations and an overlapping phenotype that included intellectual disability, distinctive facial dysmorphism and skeletal/connective tissue abnormalities. Whilst we had attempted (unsuccessfully) to identify additional cases through existing collaborators, the two published cases were 'matched' using GeneMatcher, a web-based tool for connecting researchers and clinicians working on identical genes. Our report therefore exemplifies the importance of such online tools in clinical genetics research and the benefits of periodically reviewing cases with variants of unproven significance. Our study also suggests that loss of function variants in HNRNPK should be considered as a molecular basis for patients with Kabuki-like syndrome.

Carbon dating cancer: defining the chronology of metastatic progression in colorectal cancer

Background

Patients often ask oncologists how long a cancer has been present before causing symptoms or spreading to other organs. The evolutionary trajectory of cancers can be defined using phylogenetic approaches but lack of chronological references makes dating the exact onset of tumours very challenging.

Patients and methods

Here, we describe the case of a colorectal cancer (CRC) patient presenting with synchronous lung metastasis and metachronous thyroid, chest wall and urinary tract metastases over the course of 5 years. The chest wall metastasis was caused by needle tract seeding, implying a known time of onset. Using whole genome sequencing data from primary and metastatic sites we inferred the complete chronology of the cancer by exploiting the time of needle tract seeding as an in vivo 'stopwatch'. This approach allowed us to follow the progression of the disease back in time, dating each ancestral node of the phylogenetic tree in the past history of the tumour. We used a Bayesian phylogenomic approach, which accounts for possible dynamic changes in mutational rate, to reconstruct the phylogenetic tree and effectively 'carbon date' the malignant progression.

Results

The primary colon cancer emerged between 5 and 8 years before the clinical diagnosis. The primary tumour metastasized to the lung and the thyroid within a year from its onset. The thyroid lesion presented as a tumour-to-tumour deposit within a benign Hurthle adenoma. Despite rapid metastatic progression from the primary tumour, the patient showed an indolent disease course. Primary cancer and metastases were microsatellite stable and displayed low chromosomal instability. Neo-antigen analysis suggested minimal immunogenicity.

Conclusion

Our data provide the first in vivo experimental evidence documenting the timing of metastatic progression in CRC and suggest that genomic instability might be more important than the metastatic potential of the primary cancer in dictating CRC fate.

Disordered eating in French high-level athletes: association with type of sport, doping behavior, and psychological features

PURPOSE

Over the last few years, disordered eating in athletes has received increasing attention. According to several studies, athletes could be more vulnerable to disordered eating and some characteristics specific to the athletic community could be in favour of an increased risk of poor body image and disturbed eating habits in athletes. However, the literature is sparse and some methodological issues in studies have been pointed out. In this context, we aimed at determining the prevalence of disordered eating in French high-level athletes using clinical interviews of three different clinicians and identifying what are the factors associated with disordered eating in athletes.

METHODS

In France, all athletes registered on the French high-level list have to undergo a yearly evaluation. Data collected during the somatic assessment, the dietary consultation, and the psychological of the yearly evaluation were used. Multivariate analysis was performed for identification of factors associated with disordered eating.

RESULTS

Out of the 340 athletes included, 32.9% have been detected with a disordered eating. They were difficult to detect by clinicians, as usual criteria did not seem to be reliable for athletes. Competing in sports emphasizing leanness or low body weight was associated with disordered eating; however, gender was not.

CONCLUSION

These results highlight the need for the development of specific screening tools for high-level athletes. Furthermore, the identification of factors associated with disordered eating could improve early detection and prevention program effectiveness.

Self-organized criticality and universality in a nonconservative earthquake model

We make an extensive numerical study of a two-dimensional nonconservative model proposed by Olami, Feder, and Christensen to describe earthquake behavior [Phys. Rev. Lett. 68, 1244 (1992)]. By analyzing the distribution of earthquake sizes using a multiscaling method, we find evidence that the model is critical, with no characteristic length scale other than the system size, in agreement with previous results. However, in contrast to previous claims, we find a convergence to universal behavior as the system size increases, over a range of values of the dissipation parameter alpha. We also find that both "free" and "open" boundary conditions tend to the same result. Our analysis indicates that, as L increases, the behavior slowly converges toward a power law distribution of earthquake sizes P(s) approximately equal s(-tau) with an exponent tau approximately equal 1.8. The universal value of tau we find numerically agrees quantitatively with the empirical value (tau=B+1) associated with the Gutenberg-Richter law.

Scaling in a nonconservative earthquake model of self-organized criticality

We numerically investigate the Olami-Feder-Christensen model for earthquakes in order to characterize its scaling behavior. We show that ordinary finite size scaling in the model is violated due to global, system wide events. Nevertheless we find that subsystems of linear dimension small compared to the overall system size obey finite (subsystem) size scaling, with universal critical coefficients, for the earthquake events localized within the subsystem. We provide evidence, moreover, that large earthquakes responsible for breaking finite-size scaling are initiated predominantly near the boundary.