Pioneer transcription factors have key roles in development as master regulators of cell fate specification. Only a small fraction of all transcription factors have the pioneer ability that confers access to target genomic DNA sites embedded in so-called “closed” heterochromatin. This ability to seek and bind target sites within the silenced portion of the epigenome is the basis for their role in changing cell fate. Upon binding heterochromatin sites, pioneer factors trigger remodelling of chromatin from a repressed into an active organization. This action is typically exerted at enhancer regulatory sequences, thus allowing activation of new gene subsets. During pituitary development, the only pioneer with a well-documented role is Pax7 that specifies the intermediate lobe melanotrope cell fate. In this review, a particular focus is placed on this Pax7 function but its properties are also considered within the general context of pioneer factor action. Given their potent activity to reprogram gene expression, it is not surprising that many pioneers are associated with tumor development. Over-expression or chromosomal translocations leading to production of chimeric pioneers have been implicated in different cancers. We review here the current knowledge on the mechanism of pioneer factor action.
Juliette Harris, Arthur Gouhier, and Jacques Drouin
Rolf H H Groenwold and Olaf M Dekkers
The validity of clinical research is potentially threatened by missing data. Any variable measured in a study can have missing values, including the exposure, the outcome, and confounders. When missing values are ignored in the analysis, only those subjects with complete records will be included in the analysis. This may lead to biased results and loss of power. We explain why missing data may lead to bias and discuss a commonly used classification of missing data.
C A Lebbink, B L Dekker, G Bocca, A J A T Braat, J P M Derikx, M P Dierselhuis, B de Keizer, S Kruijff, A B G Kwast, F H van Nederveen, E J M Nieveen van Dijkum, R A J Nievelstein, R P Peeters, C E J Terwisscha van Scheltinga, W J E Tissing, K van der Tuin, M R Vriens, J Zsiros, A S P van Trotsenburg, T P Links, and H M van Santen
Currently, there are no European recommendations for the management of pediatric thyroid cancer. Other current international guidelines are not completely concordant. In addition, medical regulations differ between, for instance, the US and Europe. We aimed to develop new, easily accessible national recommendations for differentiated thyroid carcinoma (DTC) patients <18 years of age in the Netherlands as a first step toward a harmonized European Recommendation.
A multidisciplinary working group was formed including pediatric and adult endocrinologists, a pediatric radiologist, a pathologist, endocrine surgeons, pediatric surgeons, pediatric oncologists, nuclear medicine physicians, a clinical geneticist and a patient representative. A systematic literature search was conducted for all existing guidelines and review articles for pediatric DTC from 2000 until February 2019. The Appraisal of Guidelines, Research and Evaluation (AGREE) instrument was used for assessing quality of the articles. All were compared to determine dis- and concordances. The American Thyroid Association (ATA) pediatric guideline 2015 was used as framework to develop specific Dutch recommendations. Discussion points based upon expert opinion and current treatment management of DTC in children in the Netherlands were identified and elaborated.
Based on the most recent evidence combined with expert opinion, a 2020 Dutch recommendation for pediatric DTC was written and published as an online interactive decision tree (www.oncoguide.nl).
Pediatric DTC requires a multidisciplinary approach. The 2020 Dutch Pediatric DTC Recommendation can be used as a starting point for the development of a collaborative European recommendation for treatment of pediatric DTC.
Maria Cristina Campopiano, Debora Podestà, Francesca Bianchi, Carlotta Giani, Laura Agate, Valeria Bottici, Virginia Cappagli, Loredana Lorusso, Antonio Matrone, Luciana Puleo, Laura Valerio, David Viola, Paolo Piaggi, Rossella Elisei, and Eleonora Molinaro
At present, recombinant TSH cannot be used for the treatment of metastatic differentiated thyroid cancer patients. The aim of this study was to evaluate if the type of TSH stimulation, recombinant or endogenous, had an impact on the outcome of these patients.
Design and methods:
We compared the outcome of two propensity score-matched groups of metastatic patients, stimulated by either only recombinant TSH (n = 43) or only endogenous TSH (n = 34).
As expected from the matching procedure, the clinical–pathological features and the cumulative 131-I activities administered to the two groups were very similar. After 4 years of follow-up, 4% of patients were cured, 3% had biochemical disease and 93% had structural disease. However, 91% of patients obtained a clinical benefit from this therapy in terms of stabilization of the disease or complete remission or partial response. When considering the two groups separately, we did not find any difference in their outcome. When considering the response to 131-I therapy of the single type of metastases, 8% of lymph node metastases and 8% of lung metastases disappeared but none of the bone metastases. The response to 131-I therapy of the single type of metastases was similar when we looked at the two groups separately.
This study shows (i) an overall clinical benefit of the 131-I therapy, since the majority of patients remained affected but with a stable disease, and (ii) that the preparation with either recombinant or endogenous TSH has no impact on the 131-I therapy efficacy and the outcome of our two groups of patients.
Ronit Marom, Brien M Rabenhorst, and Roy Morello
Osteogenesis imperfecta (OI) is an inherited skeletal dysplasia characterized by bone fragility and skeletal deformities. While the majority of cases are associated with pathogenic variants in COL1A1 and COL1A2, the genes encoding type I collagen, up to 25% of cases are associated with other genes that function within the collagen biosynthesis pathway or are involved in osteoblast differentiation and bone mineralization. Clinically, OI is heterogeneous in features and variable in severity. In addition to the skeletal findings, it can affect multiple systems including dental and craniofacial abnormalities, muscle weakness, hearing loss, respiratory and cardiovascular complications. A multi-disciplinary approach to care is recommended to address not only the fractures, reduced mobility, growth and bone pain but also other extra-skeletal manifestations. While bisphosphonates remain the mainstay of treatment in OI, new strategies are being explored, such as sclerostin inhibitory antibodies and TGF beta inhibition, to address not only the low bone mineral density but also the inherent bone fragility. Studies in animal models have expanded the understanding of pathomechanisms of OI and, along with ongoing clinical trials, will allow to develop better therapeutic approaches for these patients.
Nuria Valdés, Amit Tirosh, Meg Keil, Constantine A Stratakis, and Maya Lodish
Objective: Due to the rarity of Cushing´s syndrome (CS) in children and adolescents, data are scarce about body mass index (BMI) during active disease and following remission. Therefore, our aim was to analyze BMI after long term-remission and determine predictive factors for promptly identifying patients at risk of being overweight or obese after remission for CS.
Design: Retrospective cohort study.
Patients: 73 patients: 58 (79.4%) had Cushing disease, 40 males (58%), median age of 12 years (IQR: 9-15). The mean follow-up time was 22.4±18.2 months (range: 4-98).
Methods: Main Outcome Measures: BMI, lipid profile, blood pressure, HOMA-IR.
Results: At diagnosis, only 8 (11%) patients had a normal weight. Although the BMI z-score at the last follow-up improved (2.0±0.7 to 1.0±1.2,P<0.001), 44% remained overweight or obese after 2 years of remission according to the Kaplan-Meier curves. The BMI z-scores at the last follow-up correlated only with HOMA-IR levels (r:0.49,P=0.027). We found 2 independent factors related to reaching a normal weight: BMI z-score at diagnosis (HR:0.156, 95%CI:0.038-0.644;P=0.01) and BMI z-score change at 6±2 months (HR:2.980, 95%CI:1.473-6.028;P=0.002), which had high accuracy when a cutoff of 0.5 was used for ROC analysis (AUC=0.828 (0.67-0.97;P<0.001).
Conclusions: Children and adolescents with CS have a high risk of being overweight or obese after successful treatment for their disease. At risk patients can be identified quickly based on their baseline BMI and initial weight loss after surgery. Efforts should focus on adopting healthy diet and lifestyle in the immediate postoperative period.
Robin Michelet, Johanna Melin, Zinnia P. Parra-Guillen, Uta Neumann, J Martin Whitaker, Viktoria Stachanow, Wilhelm Huisinga, John Porter, Oliver Blankenstein, Richard J. Ross, and Charlotte Kloft
Accurate hydrocortisone dosing in children with adrenal insufficiency is important to avoid the risks of over and under treatment including iatrogenic Cushing’s syndrome and adrenal crisis.
To establish a population pharmacokinetic model of hydrocortisone in children and use this to refine hydrocortisone replacement regimens.
Design and methods:
Pharmacokinetic study of hydrocortisone granules, available in 0.5, 1, 2 and 5 mg dose strengths, in 24 children with adrenal insufficiency aged 2 weeks to 6 years. Cortisol concentrations quantified by LC-MS/MS were used to refine an adult pharmacokinetic model to a paediatric population model which was then used to simulate seven different hydrocortisone treatment regimens.
Pre-dose cortisol levels were undetectable in 54% of the 24 children. The developed pharmacokinetic model had good predictive performance. Simulations for the seven treatment regimens using either three- or four-times daily dosing showed treatment regimens delivered an AUC0- 24h within the 90% reference range for healthy children except in neonates where two regimens had an AUC below the 5th percentile. Cortisol concentrations at individual time points in the 24 h were outside the 90% reference range for healthy individuals in 50%, 55–65% and 70–75% for children, infants and neonates, respectively, with low cortisol levels being most prevalent.
Current paediatric hydrocortisone treatment regimens based on either three- or four-times daily administration replicate cortisol exposure based on AUC0- 24h, but the majority of cortisol levels are above or below physiological cortisol levels with low levels very common before the next dose.
Tal Oron, Liora Lazar, Ilan Feldhamer, Mira Manor, Nira Koren-Morag, Ariel Tenenbaum, and Joseph Meyerovitch
The need for personalization of the reference values of thyroid function tests has been previously suggested. We aimed at determining TSH reference values in a large cohort of children according to age, sex, BMI, and ethnicity.
A population-based cohort study.
The study cohort included 75 549 healthy children aged 5–18 years. Data analyzed included age, gender, TSH, FT4 levels, BMI and ethnicity. Multivariate logistic regression analysis examined the associations between the study parameters.
TSH in the Jewish population is lower than in the non-Jewish population (median: 2.1 IU/L (IQR: 1.5) vs 2.2 IU/L (IQR: 1.5), P < 0.0001). TSH is significantly affected by BMI for children defined as underweight, normal weight, overweight or obese, levels increased as weight diverged from the normal range (median levels: 2.1 IU/L (IQR: 1.4), 2.0 IU/L (IQR: 1.3), 2.1 IU/L (IQR: 1.4), 2.4 (IQR: 1.5), respectively, P < 0.001). The 2.5 percentile is affected by gender and BMI (P < 0.02 and P < 0.001, respectively), while the 97.5 percentile is affected by ethnic origin and BMI (P < 0.001 for both). New TSH reference intervals (RI) adjusted according to BMI and ethnicity are suggested. Comparison of the old and new RI demonstrate the significance of RI personalization: 25.1% of the children with TSH levels above the old RI are within the new RI, while 2.3% of the children who were in the old RI are below the new RI.
TSH reference values in children are affected by BMI and ethnicity. Reference values should be individualized accordingly to improve future clinical decision-making and treatment.
Bruno Donadille, Sophie Tuffet, Clement Cholet, Mariana Nedelcu, Nathalie Bourcigaux, Laurence Iserin, Laurence Monnier-Cholley, Alexandra Rousseau, and Sophie Christin-Maitre
Turner syndrome (TS) is a rare disorder affecting 1/2500 female newborn. Aortic dilatation (AD) and aortic dissection represent a major concern in TS. The aims of our study were to describe the aortic root growth, potential aortic dilatation (AD) risk factors and cardiovascular outcomes in a cohort of patients with TS.
Among 204 adult patients included, 197 were studied using a standardized 1.5 Tesla MRI protocol. AD was defined as an aortic diameter ≥20 mm/m2 at the Valsalva sinuses and/or at the ascending aorta, when indexed to body surface area.
At baseline, AD was present in 81/197 (41.1%) and 32/197 (16.2%) of patients, at the levels of Valsalva and ascending aorta, respectively. The aortic Valsalva diameter was larger in patients treated for thyroiditis (P < 0.001). Potential risk factors of AD were aging (P < 0.001) and the presence of bicuspid aortic valve (BAV) (P = 0.002). The hazard ratio (HR) of AD occurrence in the presence of BAV was 2.2 (95% CI: 1.33–3.71). After a median follow-up period of 5.1 years (n = 143), AD was present in 58/143 (40.6%) and 25/143 (17.5%) of patients at the levels of Valsalva and ascending aorta, respectively. The median aortic growth of the Valsalva sinuses remained stable. At the ascending aorta, it increased by 0.14 ± 0.61 mm/year. Only one aortic-related death was observed.
AD is common in adult patients with TS. However, our results are rather reassuring, as the median aortic diameters remained stable after 5.1 years and few aortic events were observed.
I C M Pelsma, N R Biermasz, A M Pereira, W R van Furth, N M Appelman-Dijkstra, M Kloppenburg, H M Kroon, and K M J A Claessen
Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) excess results in both reversible and irreversible musculoskeletal damage, including increased vertebral fracture (VF) risk. The prevalence of VFs is approximately 60% in controlled acromegaly patients, and these VFs can progress in time. We aimed to identify the course of VFs in a cohort of acromegaly patients in long-term remission and their associated risk factors during prolonged follow-up.
Thirty-one patients with acromegaly (49% female, median age 60 years (IQR 53–66)), who were in remission for ≥2 years, were included in this longitudinal, prospective, follow-up study. Spine radiographs of vertebrae Th4 to L4 were assessed for VFs using the Genant score, at baseline, after 2.6 years and 9.1 years. Progression was defined as either a new fracture or a ≥1-point increase in Genant score.
The prevalence of VF at baseline was 87% (27/31 patients). Progression of VFs was observed in eleven patients (35.5%) during the 9.1-year follow-up period, with a total incidence rate of 65.5 per 1000 person years (males 59.8 per 1000 person years vs females 71.6 per 1000 person years). Patients treated with surgery or radiotherapy had a higher risk of VF progression in this cohort (P = 0.030).
In this cohort of long-term, well-controlled acromegalic patients, the prevalence and progression of VFs was high, showing that the deleterious effects of GH and IGF-1 excess on bone persist despite achievement of longstanding remission.