Alternative strategies for deciphering the genetic architecture of childhood Pre-B acute lymphoblastic leukemia

La leucémie lymphoblastique aigüe (LLA) est une maladie génétique complexe. Malgré que cette maladie hématologique soit le cancer pédiatrique le plus fréquent, ses causes demeurent inconnues. Des études antérieures ont démontrées que le risque à la LLA chez l’enfant pourrait être influencé par des gènes agissant dans le métabolisme des xénobiotiques, dans le maintient de l’intégrité génomique et dans la réponse au stress oxydatif, ainsi que par des facteurs environnementaux. Au cours de mes études doctorales, j’ai tenté de disséquer davantage les bases génétiques de la LLA de l’enfant en postulant que la susceptibilité à cette maladie serait modulée, au moins en partie, par des variants génétiques agissant dans deux voies biologiques fondamentales : le point de contrôle G1/S du cycle cellulaire et la réparation des cassures double-brin de l’ADN. En utilisant une approche unique reposant sur l’analyse d’une cohorte cas-contrôles jumelée à une cohorte de trios enfants-parents, j’ai effectué une étude d’association de type gènes/voies biologiques candidats. Ainsi, j’ai évaluer le rôle de variants provenant de la séquence promotrice de 12 gènes du cycle cellulaire et de 7 gènes de la voie de réparation de l’ADN, dans la susceptibilité à la LLA. De tels polymorphismes dans la région promotrice (pSNPs) pourraient perturber la liaison de facteurs de transcription et mener à des différences dans les niveaux d’expression des gènes pouvant influencer le risque à la maladie. En combinant différentes méthodes analytiques, j’ai évalué le rôle de différents mécanismes génétiques dans le développement de la LLA chez l’enfant. J’ai tout d’abord étudié les associations avec gènes/variants indépendants, et des essaies fonctionnels ont été effectués afin d’évaluer l’impact des pSNPs sur la liaison de facteurs de transcription et l’activité promotrice allèle-spécifique. Ces analyses ont mené à quatre publications. Il est peu probable que ces gènes de susceptibilité agissent seuls; j’ai donc utilisé une approche intégrative afin d’explorer la possibilité que plusieurs variants d’une même voie biologique ou de voies connexes puissent moduler le risque de la maladie; ces travaux ont été soumis pour publication. En outre, le développement précoce de la LLA, voir même in utero, suggère que les parents, et plus particulièrement la mère, pourraient jouer un rôle important dans le développement de cette maladie chez l’enfant. Dans une étude par simulations, j’ai évalué la performance des méthodes d’analyse existantes de détecter des effets fœto-maternels sous un design hybride trios/cas-contrôles. J’ai également investigué l’impact des effets génétiques agissant via la mère sur la susceptibilité à la LLA. Cette étude, récemment publiée, fût la première à démontrer que le risque de la leucémie chez l’enfant peut être modulé par le génotype de sa mère. En conclusions, mes études doctorales ont permis d’identifier des nouveaux gènes de susceptibilité pour la LLA pédiatrique et de mettre en évidence le rôle du cycle cellulaire et de la voie de la réparation de l’ADN dans la leucémogenèse. À terme, ces travaux permettront de mieux comprendre les bases génétiques de la LLA, et conduiront au développement d’outils cliniques qui amélioreront la détection, le diagnostique et le traitement de la leucémie chez l’enfant.Childhood acute lymphoblastic leukemia (ALL) is a complex and heterogeneous genetic disease. Although it is the most common pediatric cancer, its etiology remains poorly understood. Previous studies provided evidence that childhood ALL might originate through the collective contribution of different genes controlling the efficiency of carcinogen metabolism, the capacity of maintaining DNA integrity and the response to oxidative stress, as well as environmental factors. In my doctoral research project I attempted to further dissect the genetic intricacies underlying childhood ALL. I postulated that a child’s susceptibility to ALL may be influenced, in part, by functional sequence variation in genes encoding components of two core biologic pathways: G1/S cell cycle control and DNA double-strand break repair. Using a unique two-tiered study design consisting of both unrelated ALL cases and healthy controls, as well as case-parent trios, I performed a pathway-based candidate-gene association study to investigate the role of sequence variants in the promoter regions of 12 candidate cell cycle genes and 7 DNA repair genes, in modulating ALL risk among children. Polymorphisms in promoter regions (pSNPs) could perturb transcription factor binding and lead to differences in gene expression levels that in turn could modify the risk of disease. To better depict the complex genetic architecture of childhood ALL, I used multiple analytical approaches. First, individual genes/variants were tested for association with disease, while functional in vitro validation was performed to evaluate the impact of the pSNPs on differential transcription factor binding and allele-specific promoter activity. These analyses led to four published articles. Given that these genes are not likely to act alone to confer disease risk I used an integrative approach to explore the possibility that combinations of functionally relevant pSNPs among several components of the same or of interconnected pathways, could contribute to modified childhood ALL risk either through pathway-specific or epistatic effects; this work was recently submitted for publication. Finally, childhood ALL is thought to arise in utero suggesting that the parents, and in particular the mother, may play an important role in shaping disease susceptibility in their offspring. Using simulations, I investigated the performance of existing methods to test for maternal genotype associations using a case-parent trio/case-control hybrid design, and then assessed the impact of maternally-mediated genetic effects on ALL susceptibility among children. This published work was the first to show that the mother’s genotype can indeed influence the risk of leukemia in children, further corroborating the importance of considering parentally-mediated effects in the study of early-onset diseases. In conclusion, my doctoral work lead to the identification of novel genetic susceptibility loci for childhood ALL and provided evidence for the implication of the cell cycle control and DNA repair pathways in leukemogenesis. Better elucidation of the genetic mechanisms underlying the pathogenesis of ALL in children could be of great diagnostic value and provide data to help guide risk-directed therapy and improve disease management and outcome. Ultimately, this study brings us one step closer to unraveling the genetic architecture of childhood ALL and provides a stepping-stone towards disease prevention

Detection of Fetomaternal Genotype Associations in Early-Onset Disorders: Evaluation of Different Methods and Their Application to Childhood Leukemia

Several designs and analytical approaches have been proposed to dissect offspring from maternal genetic contributions to early-onset diseases. However, lack of parental controls halts the direct verification of the assumption of mating symmetry (MS) required to assess maternally-mediated effects. In this study, we used simulations to investigate the performance of existing methods under mating asymmetry (MA) when parents of controls are missing. Our results show that the log-linear, likelihood-based framework using a case-triad/case-control hybrid design provides valid tests for maternal genetic effects even under MA. Using this approach, we examined fetomaternal associations between 29 SNPs in 12 cell-cycle genes and childhood pre-B acute lymphoblastic leukemia (ALL). We identified putative fetomaternal effects at loci CDKN2A rs36228834 (P = .017) and CDKN2B rs36229158 (P = .022) that modulate the risk of childhood ALL. These data further corroborate the importance of the mother's genotype on the susceptibility to early-onset diseases

Ancient Human Parasites in Ethnic Chinese Populations

Whilst archaeological evidence for many aspects of life in ancient China is well studied, there has been much less interest in ancient infectious diseases, such as intestinal parasites in past Chinese populations. Here, we bring together evidence from mummies, ancient latrines, and pelvic soil from burials, dating from the Neolithic Period to the Qing Dynasty, in order to better understand the health of the past inhabitants of China and the diseases endemic in the region. Seven species of intestinal parasite have been identified, namely roundworm, whipworm, Chinese liver fluke, oriental schistosome, pinworm, Taenia sp. tapeworm, and the intestinal fluke Fasciolopsis buski. It was found that in the past, roundworm, whipworm, and Chinese liver fluke appear to have been much more common than the other species. While roundworm and whipworm remained common into the late 20th century, Chinese liver fluke seems to have undergone a marked decline in its prevalence over time. The iconic transport route known as the Silk Road has been shown to have acted as a vector for the transmission of ancient diseases, highlighted by the discovery of Chinese liver fluke in a 2,000 year-old relay station in northwest China, 1,500 km outside its endemic range

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Increasing frailty is associated with higher prevalence and reduced recognition of delirium in older hospitalised inpatients: results of a multi-centre study

Purpose: Delirium is a neuropsychiatric disorder delineated by an acute change in cognition, attention, and consciousness. It is common, particularly in older adults, but poorly recognised. Frailty is the accumulation of deficits conferring an increased risk of adverse outcomes. We set out to determine how severity of frailty, as measured using the CFS, affected delirium rates, and recognition in hospitalised older people in the United Kingdom. Methods: Adults over 65 years were included in an observational multi-centre audit across UK hospitals, two prospective rounds, and one retrospective note review. Clinical Frailty Scale (CFS), delirium status, and 30-day outcomes were recorded. Results: The overall prevalence of delirium was 16.3% (483). Patients with delirium were more frail than patients without delirium (median CFS 6 vs 4). The risk of delirium was greater with increasing frailty [OR 2.9 (1.8–4.6) in CFS 4 vs 1–3; OR 12.4 (6.2–24.5) in CFS 8 vs 1–3]. Higher CFS was associated with reduced recognition of delirium (OR of 0.7 (0.3–1.9) in CFS 4 compared to 0.2 (0.1–0.7) in CFS 8). These risks were both independent of age and dementia. Conclusion: We have demonstrated an incremental increase in risk of delirium with increasing frailty. This has important clinical implications, suggesting that frailty may provide a more nuanced measure of vulnerability to delirium and poor outcomes. However, the most frail patients are least likely to have their delirium diagnosed and there is a significant lack of research into the underlying pathophysiology of both of these common geriatric syndromes

La leucémie de l’enfant

Le cancer affecte 1 enfant sur 500 avant l’âge de 14 ans et constitue la cause majeure de mortalité par maladie dans cette population. L’étiologie de ce groupe de maladies hétérogènes est encore très mal connue. Du fait de leur plus grande prévalence, les efforts de recherche en oncogénétique pédiatrique se sont concentrés sur les leucémies, particulièrement sur la leucémie lymphoblastique aiguë (LLA). Bien que l’importance de la variabilité interindividuelle dans la susceptibilité au cancer soit acceptée, il existe peu d’études analysant l’impact des polymorphismes sur la susceptibilité aux leucémies de l’enfant. Les principales voies biologiques contribuant à la susceptibilité au cancer peuvent être regroupées comme suit : (1) croissance et différenciation cellulaires, (2) réplication et réparation de l’ADN, (3) métabolisme des xénobiotiques, (4) apoptose, (5) réponse au stress oxydant, (6) cycle cellulaire. Des études d’association ciblant des gènes candidats engagés dans ces processus biologiques ont été entreprises afin d’analyser les déterminants génétiques de la leucémogenèse chez l’enfant. Nous avons démontré que celle-ci est associée à des variants génétiques et que la combinaison des génotypes a une plus grande valeur prédictive du risque que les génotypes pris indépendamment les uns des autres. La complexité des interactions entre l’environnement et la variabilité interindividuelle face à la susceptibilité au cancer, que montrent ces résultats, suggère que la compréhension de la physiopathologie des leucémies de l’enfant passe par l’étude génétique de plusieurs enzymes (ou voies métaboliques)

The surgical admissions proforma: Does it make a difference?

Admissions records are essential in communicating key information regarding unwell patients and at handover of care. We designed, implemented and evaluated the impact of a standardised surgical clerking proforma on documentation and clinician acceptability in comparison to freehand clerking. A clerking proforma was implemented for all acute general surgical admissions. Documentation was assessed according to 32 criteria based on the Royal College of Surgeons of England guidelines, for admissions before (n = 72) and after (n = 96) implementation. Fisher's exact test and regression analysis were used to compare groups. Surgical team members were surveyed regarding attitudes towards the new proforma. Proforma uptake was 73%. After implementation, documentation increased in 28/32 criteria. This was statistically significant in 17 criteria, including past surgical history (p < 0.01), medication history (p = 0.03), ADLs (p = 0.02), systems review (p < 0.01), blood pressure (p < 0.01), blood results (p = 0.02) and advice given to the patient (p = 0.02). The proforma remained beneficial after regression analysis accounted for differences in time of day, seniority of the doctor and nights or weekends (coefficient = 0.12 [p < 0.01]). 89% of the surgical team felt the form improved quality of documentation and preferred its use to freehand clerking. 94% felt it was beneficial on the post-take ward-round. Audit quality control was also more reliable with the proforma (inter-observer agreement = 99.3% [κ = 0.997]) versus freehand clerking (97.1% [κ = 0.941]). Our study demonstrates that a standardised surgical clerking proformas improves the quantity and quality of documentation in comparison to freehand clerking, is preferred by health professionals and improves reliability of the audit quality control process