Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders.

Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism and hair anomalies. PNPLA6 encodes neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a systematic evidence-based review of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6-associated clinical diagnoses unambiguously reclassified 36 variants as pathogenic and 10 variants as likely pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship, and the generation of a preclinical animal model, pave the way for therapeutic trials, using NTE as a biomarker.

The qMini assay identifies an overlooked class of splice variants.

Splice variants are known to cause diseases by utilizing alternative splice sites, potentially resulting in protein truncation or mRNA degradation by nonsense-mediated decay. Splice variants are verified when altered mature mRNA sequences are identified in RNA analyses or minigene assays. Using a quantitative minigene assay, qMini, we uncovered a previously overlooked class of disease-associated splice variants that did not alter mRNA sequence but decreased mature mRNA level, suggesting a potentially new pathogenic mechanism.

Neuropathy target esterase activity predicts retinopathy among PNPLA6 disorders.

Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism, and hair anomalies. PNPLA6 encodes Neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a clinical meta-analysis of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6 -associated clinical diagnoses unambiguously reclassified 10 variants as likely pathogenic and 36 variants as pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship and the generation of a preclinical animal model pave the way for therapeutic trials, using NTE as a biomarker.

Associations between weight-based teasing and disordered eating behaviors among youth.

Weight-based teasing (WBT) is commonly reported among youth and is associated with disinhibited and disordered eating. Specifically, youth who experience WBT may engage in disordered eating behaviors to cope with the resultant negative affect. Therefore, we examined associations between WBT and disordered eating behaviors among youth and assessed whether negative affect mediated these relationships. Two hundred one non-treatment seeking youth (8-17y) completed questionnaires assessing WBT, disinhibited eating, depression, and anxiety. Disordered eating and loss-of-control (LOC) eating were assessed via semi-structured interview. Analyses of covariance were conducted to examine relationships between WBT and eating-related variables, and bootstrapping mediation models were used to evaluate negative affect (a composite of depressive and anxiety symptoms) as a mediator of these associations. All models were adjusted for sex, race, age, and adiposity. Among 201 participants (13.1 ± 2.8y; 54.2% female; 30.3% Black; 32.8% with overweight/obesity), WBT was associated with emotional eating, eating in the absence of hunger, and disordered eating attitudes and behaviors (ps ≤ 0.02). These associations were all mediated by negative affect. WBT was also associated with a threefold greater likelihood of reporting a recent LOC eating episode (p = .049). Among boys and girls across weight strata, WBT was associated with multiple aspects of disordered eating and these relationships were mediated by negative affect. Longitudinal studies are needed to clarify the directionality of these associations and to identify subgroups of youth that may be particularly vulnerable to WBT and its sequelae.

Inhibitory control and negative affect in relation to food intake among youth.

Negative affect and poor inhibitory control are related to disinhibited eating behaviors in youth and may contribute to the development and/or maintenance of obesity. Although few studies have jointly examined these constructs in youth, it has been theorized that poor inhibitory control may be driven by negative affect. If supported, impaired inhibitory control, driven by negative affect, could represent a modifiable neurocognitive treatment target for disinhibited eating. The current study examined whether inhibitory control mediates the relationship between negative affect and eating among youth. Youth (8-17 years) participated in a Food Go/No-Go neurocognitive task to measure inhibitory control as the percentage of commission errors. A composite negative affect score was created from self-report measures of anxiety and depression. A laboratory buffet meal modeled to simulate disinhibited eating was used to measure total and snack food intake. Cross-sectional mediation models with bias-corrected bootstrap confidence intervals (CI) were conducted using negative affect as the independent variable, inhibitory control as the mediator, and intake patterns as dependent variables. One-hundred-eighty-one youths (13.2 ± 2.7y; 55% female; BMIz 0.6 ± 1.0) were studied. Total Go/No-Go commission errors mediated the relationship between negative affect and total intake (95%CI = [0.3, 31.6]), but not snack intake (95%CI = [-2.5, 7.3]). Commission errors for Food-Go blocks significantly mediated the relationship between negative affect and total intake (95%CI = [7.7, 44.4]), but not snack intake (95%CI = [-3.4, 9.5]). Commission errors on Neutral-Go blocks did not significantly mediate any of these relationships. Negative affect may lead to poorer inhibitory control as well as a stronger approach tendency toward food, increasing the likelihood of engaging in disinhibited eating. Future research should determine if, in combination with approaches to reduce negative affect, improved inhibitory control could help prevent overeating in youths with depressive or anxiety symptoms.

Assessment of loss-of-control eating in healthy youth by interview and questionnaire.

OBJECTIVE: The aim of this study is to evaluate two questionnaires, an updated youth version of the questionnaire on eating and weight patterns (Questionnaire on Eating and Weight Patterns-5 Children/Adolescent [QEWP-C-5]) and the Loss-of-Control (LOC) Eating Disorder Questionnaire (LOC-ED-Q), against the Eating Disorder Examination (EDE) interview to assess the presence of LOC-eating among youth. METHOD: Two-hundred and eighteen youths (12.8 ± 2.7 years) completed the QEWP-C-5, LOC-ED-Q, and EDE, depressive and anxiety questionnaires, and adiposity assessment. Sensitivity, specificity, positive-predictive value, negative-predictive value, and diagnostic accuracy were calculated; Cochran's Q and McNemar's tests were used to compare measures. Receiver operating characteristic area under the curve (AUC) analyses were performed. Mood and adiposity based on LOC-eating presence and absence based on each measure were examined. RESULTS: The QEWP-C-5 and LOC-ED-Q demonstrated poor sensitivity (33%; 30%) and high specificity (95%; 96%) compared with the EDE. The AUCs suggested neither the QEWP-C-5 (0.64) nor the LOC-ED-Q (0.62) demonstrated acceptable diagnostic accuracy. Comparing distributions of LOC-eating presence between assessments, the QEWP-C-5 and EDE did not differ significantly (p = .10), while the LOC-ED-Q and EDE had significantly different distributions (p = .03). LOC-eating presence was associated with higher depressive and anxiety symptoms across all measures (ps < .02). Greater adiposity (ps < .02) was associated with LOC-eating presence on the EDE and LOC-ED-Q, and higher BMI z-score (p = .02) on the LOC-ED-Q. DISCUSSION: Neither the QEWP-C-5 nor the LOC-ED-Q was sensitive for identifying LOC-eating presence as determined by the EDE, although both were associated with greater mood symptoms. Research is needed to improve self-report questionnaires to better screen for LOC-eating presence among pediatric populations.