Heterozygous loss-of-function SMC3 variants are associated with variable growth and developmental features.

Heterozygous missense variants and in-frame indels in SMC3 are a cause of Cornelia de Lange syndrome (CdLS), marked by intellectual disability, growth deficiency, and dysmorphism, via an apparent dominant-negative mechanism. However, the spectrum of manifestations associated with SMC3 loss-of-function variants has not been reported, leading to hypotheses of alternative phenotypes or even developmental lethality. We used matchmaking servers, patient registries, and other resources to identify individuals with heterozygous, predicted loss-of-function (pLoF) variants in SMC3, and analyzed population databases to characterize mutational intolerance in this gene. Here, we show that SMC3 behaves as an archetypal haploinsufficient gene: it is highly constrained against pLoF variants, strongly depleted for missense variants, and pLoF variants are associated with a range of developmental phenotypes. Among 14 individuals with SMC3 pLoF variants, phenotypes were variable but coalesced on low growth parameters, developmental delay/intellectual disability, and dysmorphism, reminiscent of atypical CdLS. Comparisons to individuals with SMC3 missense/in-frame indel variants demonstrated an overall milder presentation in pLoF carriers. Furthermore, several individuals harboring pLoF variants in SMC3 were nonpenetrant for growth, developmental, and/or dysmorphic features, and some had alternative symptomatologies with rational biological links to SMC3. Analyses of tumor and model system transcriptomic data and epigenetic data in a subset of cases suggest that SMC3 pLoF variants reduce SMC3 expression but do not strongly support clustering with functional genomic signatures of typical CdLS. Our finding of substantial population-scale LoF intolerance in concert with variable growth and developmental features in subjects with SMC3 pLoF variants expands the scope of cohesinopathies, informs on their allelic architecture, and suggests the existence of additional clearly LoF-constrained genes whose disease links will be confirmed only by multilayered genomic data paired with careful phenotyping.

Heterozygous loss-of-function SMC3 variants are associated with variable and incompletely penetrant growth and developmental features.

Heterozygous missense variants and in-frame indels in SMC3 are a cause of Cornelia de Lange syndrome (CdLS), marked by intellectual disability, growth deficiency, and dysmorphism, via an apparent dominant-negative mechanism. However, the spectrum of manifestations associated with SMC3 loss-of-function variants has not been reported, leading to hypotheses of alternative phenotypes or even developmental lethality. We used matchmaking servers, patient registries, and other resources to identify individuals with heterozygous, predicted loss-of-function (pLoF) variants in SMC3, and analyzed population databases to characterize mutational intolerance in this gene. Here, we show that SMC3 behaves as an archetypal haploinsufficient gene: it is highly constrained against pLoF variants, strongly depleted for missense variants, and pLoF variants are associated with a range of developmental phenotypes. Among 13 individuals with SMC3 pLoF variants, phenotypes were variable but coalesced on low growth parameters, developmental delay/intellectual disability, and dysmorphism reminiscent of atypical CdLS. Comparisons to individuals with SMC3 missense/in-frame indel variants demonstrated a milder presentation in pLoF carriers. Furthermore, several individuals harboring pLoF variants in SMC3 were nonpenetrant for growth, developmental, and/or dysmorphic features, some instead having intriguing symptomatologies with rational biological links to SMC3 including bone marrow failure, acute myeloid leukemia, and Coats retinal vasculopathy. Analyses of transcriptomic and epigenetic data suggest that SMC3 pLoF variants reduce SMC3 expression but do not result in a blood DNA methylation signature clustering with that of CdLS, and that the global transcriptional signature of SMC3 loss is model-dependent. Our finding of substantial population-scale LoF intolerance in concert with variable penetrance in subjects with SMC3 pLoF variants expands the scope of cohesinopathies, informs on their allelic architecture, and suggests the existence of additional clearly LoF-constrained genes whose disease links will be confirmed only by multi-layered genomic data paired with careful phenotyping.

Incidence of Hospital-Acquired Conditions During Pediatric Clinical Research Inpatient Hospitalizations: A Matched Cohort Study.

OBJECTIVES: In this matched cohort study using data from pediatric hospitals, we compared the incidence of hospital-acquired conditions (HACs) during clinical research hospitalizations to nonresearch hospitalizations. METHODS: Using Pediatric Health Information System data for inpatient discharges January 2017-June 2022, we matched research hospitalizations (identified by International Classification of Diseases, Tenth Revision, diagnosis code) to nonresearch hospitalizations within hospital on age (±3 y), sex, discharge year (±2), and All Patients Refined Diagnosis Related Groups classification, severity of illness (±1), and risk of mortality (±1). We calculated the incidence (per 1000 discharges) and incidence rate (per 10,000 patient days) of HAC identified by International Classification of Diseases, Tenth Revision, codes and compare research versus nonresearch using logistic and Poisson regression, accounting for matching using generalized estimating equations and adjusting for sociodemographic factors and hospital utilization. RESULTS: We matched 7000 research hospitalizations to 26,447 nonresearch from 28 hospitals. Median age was 6.0 years (interquartile range, 10.6 y). Median length of stay was 4.0 days (interquartile range, 11.0 days) with longer stays among research hospitalizations ( P < 0.001). Incidence of HAC among research hospitalizations was 13.1 versus 7.2 per 1000 for nonresearch ( P < 0.001) and incidence rate 6.7 versus 4.5 per 10,000 patient days. Adjusting for sociodemographic and clinical factors, research stays had 1.65 times the odds of any HAC (95% confidence interval, 1.27-2.16; P < 0.001) and 1.38 times the incidence rate (95% confidence interval, 1.09-1.75; P = 0.009). CONCLUSIONS: Our findings indicate that pediatric research hospitalizations are more likely to experience HACs compared with nonresearch hospitalizations. These findings have important safety implications for pediatric inpatient clinical research that warrant further study.

Timing of Pubertal Onset in Girls and Boys With Constitutional Delay.

CONTEXT: The decision whether to treat a child with delayed puberty with sex steroids is primarily based on patient, family, and provider preference. Knowing when children with constitutional delay eventually enter puberty would inform this decision. OBJECTIVE, DESIGN, SETTING, PARTICIPANTS, AND OUTCOME MEASURES: To estimate and compare rates of pubertal entry, we conducted a retrospective cohort study by reviewing medical records of children evaluated for delayed puberty at a large academic medical center between 2000 and 2015, extracting data on pubertal status for all clinical visits, then conducting time-to-event analyses. RESULTS: Of 392 girls and 683 boys with delayed puberty, constitutional delay was the most common cause, found in 32% of girls and 70% of boys. In a subcohort of 97 girls and 243 boys who were prepubertal at one or more visits, we observed a broad age range for pubertal entry, up to >16 years for girls and >17 years for boys. The probability of entering puberty within the next year for 12- to 15.5-year-old girls and 13.5- to 16.5-year-old boys with delayed puberty ranged between 38% and 74%. No differences in the rates of pubertal entry were seen between girls and boys after data harmonization. CONCLUSION: The broad range of ages at pubertal entry for children with constitutional delay challenges the concept that constitutional delay is merely an extreme of normal variation. Discussions with patients and families about management should consider the possibility that some children may need to wait years after presentation until puberty starts.

A Pilot Study of Inspiratory Muscle Training to Improve Exercise Capacity in Patients with Fontan Physiology.

While the Fontan procedure has improved life expectancy, patients with single ventricle physiology have impaired exercise capacity due to limited increase in pulmonary blood flow during activity. Enhancing the "thoracic pump" using inspiratory muscle training (IMT) may ameliorate this impairment. Adult nonsmokers with Fontan physiology were recruited through Boston Children's Hospital's outpatient clinic. Participants underwent cardiopulmonary exercise testing and pulmonary function testing, followed by 12 weeks of IMT and then repeat testing. The primary endpoint was change in % predicted peak oxygen consumption (VO2). Secondary endpoints were changes in other exercise metrics. Eleven patients (6 male) were enrolled. Median ages at time of enrollment and Fontan completion were 28.8 years (25.7, 45.5) and 7.8 years (3.9, 16.5), respectively. Average baseline maximal inspiratory pressure (MIP) was normal; only 2 patients had MIP <70% predicted. Peak work rate improved significantly from baseline after 12 weeks of IMT (116.5 ± 45.0 to 126.8 ± 47.0 W, P = 0.019). Peak VO2 tended to improve (baseline 68.1 ± 14.3, change + 5.3 ± 9.6% predicted, P = 0.12), as did VE/VCO2 slope (34.1 ± 6.7 to 31.4 ± 3.6, P = 0.12). There was no change in peak tidal volume or MIP. In a small cohort of Fontan patients with mostly normal MIP, IMT was associated with significant improvement in peak work rate and a trend toward higher peak VO2 and improved ventilatory efficiency. Larger studies are needed to determine if this reflects true lack of effect or whether this pilot study was underpowered for effect size, and whether IMT is more narrowly useful for patients with impaired MIP.

Factors Associated with Clinical Research Recruitment in a Pediatric Academic Medical Center--A Web-Based Survey.

BACKGROUND: One of the most difficult aspects of conducting clinical research is the ability to successfully recruit participants. Pediatric clinical research presents unique recruitment challenges that relate to the need for parental consent on behalf of a minor, child assent, and school attendance. Yet, this has been less well studied. We conducted a survey of investigators performing human subjects research in a single large academic pediatric hospital to better understand characteristics of studies with successful recruitment. METHODS: We conducted a web-based survey from September 2011 to December 2011 of all principal investigators with an Institutional Review Board approved human subjects protocol at Boston Children's Hospital, a pediatric Academic Medical Center. The survey captured various characteristics of the protocols including study design, staffing, resources, and investigator experience and training as well as respondents' perceived barriers and facilitators to recruitment. We used chi square tests and Mantel-Haenszel test for linear trend to examine the relationship between selected predictor variables and the binary outcome of successful vs. unsuccessful recruitment and multivariable logistic regression analyses to examine the simultaneous influence of potential predictors on each outcome. RESULTS: Among the 349 eligible investigators, 52% responded to the survey, and 181 with valid data were included in the analyses. Two-thirds of the 87 protocols closed to enrollment reached 80% or more of their target enrollment, whereas, only one-third of the 94 protocols actively recruiting were meeting 80% of their target. Recruitment method appeared to be the only significant and independent factor associated with achieving 80% or more of target enrollment in closed to enrollment protocols. Closed to enrollment protocols that used recruitment in person were 4.55 times (95% CI 1.30 to 15.93; p = 0.02) more likely to achieve 80% or more of their target enrollment when compared to those that used other recruitment methods. Other potentially modifiable factors such as number of study visits, study duration and investigator experience were suggestive of being meaningfully related to recruitment. CONCLUSION: Recruiting in person may promote reaching an acceptable target enrollment in pediatric as well as adult clinical research. Future research is needed on larger and more diverse samples to gain a better understanding of how the characteristics and qualifications of the individuals who conduct recruitment influence participant enrollment as well as how best to approach patient and families for their participation.

Providing food to treat adolescents at risk for cardiovascular disease.

OBJECTIVE: Diet modification is recommended to treat childhood cardiovascular (CV) risk factors; however, the optimal dietary strategy is unknown. METHODS: In a randomized trial, the effect of a low-fat (LF) and a low-glycemic-load (LGL) reduced-calorie diet were examined in youth with overweight/obesity with CV risk factors. Using a novel intervention, we delivered LF or LGL meals and nutrition education to the home for 8 weeks (Intensive Phase), followed by 4 months Maintenance without food provision. Between-group differences in the change in insulin area under the curve (InsAUC) by oral glucose tolerance test and other risk factors were analyzed. RESULTS: Overall, participants (n = 27) showed substantial improvement during the Intensive Phase, including InsAUC (-59 ± 18.2 µU/ml × 120 min, P = 0.004), total cholesterol (-9.9 ± 3.6 mg/dl, P = 0.01), weight (-2.7 ± 0.5 kg, P < 0.001), waist circumference (-3.1 ± 0.8 cm, P < 0.001), HOMA-IR (-1.7 ± 0.4, P < 0.001), systolic blood pressure (-5 ± 1.4 mm Hg, P = 0.002), and CRP (-0.1 ± 0.1 mg/dl, P = 0.04). There were minimal between-group differences; the LF group showed greater declines in HDL (P = 0.005) and fasting glucose (P = 0.01) compared to the LGL group. Improvements waned during Maintenance. CONCLUSIONS: Home delivery of LF or LGL diets resulted in rapid and clinically important improvements in CV risk factors that diminished without food delivery and did not differ based on dietary intervention. If scalable, food provision may represent an alternative nutrition treatment strategy.

Associations of total and abdominal adiposity with risk marker patterns in children at high-risk for cardiovascular disease.

BACKGROUND: While body mass index percentiles (BMI%) are commonly used to assess childhood cardiovascular risk, waist circumference percentiles (WC%) are not commonly used nor universally accepted. We tested whether BMI% or WC% should be used to identify risk factor patterns in children at high-risk for developing cardiovascular disease (CVD). A total of 107 children (8-19 years) with cardiovascular risk factors or a family history of CVD were studied. Tobacco exposure, screen-time, blood pressure and anthropometric measures were made, as well as serum risk markers. Principal component analysis (PCA) was used to identify patterns explaining risk factor variance. Multiple linear regression was used to test for associations between risk factor patterns, BMI% and WC%. RESULTS: An adverse lipid pattern (low HDL, high triglycerides and LDL), a pro-inflammatory pattern (high ICAM and TNFαR2), a high blood pressure pattern (high SBP and DBP) and a high Lp(a) pattern were identified. Higher BMI% and WC% were associated with significantly higher levels of the lipid pattern (p < 0.05). BMI% explained 20% of variance in this pattern, whereas WC% explained 22%. When both BMI% and WC% were used together, neither BMI% nor WC% were significantly associated with the lipid pattern. However, BMI% was significantly associated with lower levels of the pro-inflammatory pattern, and WC% was associated higher levels of the pro-inflammatory pattern - together explaining 12% of variance. CONCLUSION: In children at high-risk for CVD, BMI% or WC% explained similar variance in an adverse lipid pattern; however, the combination of BMI% and WC% explained greater variance in a pro-inflammatory pattern than either alone. Both WC% and BMI% should both be used in anthropometric assessments of high-risk children.

Using high-dose omega-3 fatty acid supplements to lower triglyceride levels in 10- to 19-year-olds.

BACKGROUND: Omega-3 fatty acids supplements lower triglyceride (TG) levels in adults; little pediatric information is available. We evaluated their effect in hypertriglyceridemic adolescents. METHODS: Twenty-five patients aged 10 to 19 years with TG levels 150 to 1000 mg/dL were randomized to 6 months double-blind trial of Lovaza (~3360 mg docosahexaenoic acid + eicosapentaenoic acid per day) versus placebo. RESULTS: Baseline mean TG levels were 227 mg/dL (standard deviation = 49). TG levels declined at 3 months in the Lovaza group by 54 ± 27 mg/dL (mean ± standard error; P = .02) and by 34 ± 26 mg/dL (P = .16) in the placebo group. The difference in TG lowering between groups was not significant (P = .52). There were no between-group differences in endothelial function, blood pressure, body mass index, C-reactive protein, or side effects. CONCLUSIONS: High-dose omega-3 fatty acid supplements are well tolerated in adolescents. However, declines in TG levels did not differ significantly from Placebo in this small study.