Dhamija, Radhika

Abstract Background DDX3X- syndrome is a rare neurodevelopmental disorder characterized by varying degrees of intellectual disability, predominantly affecting females. We present an institutional cohort supplemented by a systematic literature review, expanding the cardiovascular phenotype of DDX3X- syndrome. Methods We conducted a retrospective chart review of patients diagnosed with DDX3X -syndrome at Mayo Clinic. Additionally, we performed a systematic literature review to identify studies reporting cardiovascular abnormalities in patients with DDX3X -syndrome. Results A total of 200 patients with DDX3X -syndrome were analyzed, comprising 14 patients from our institutional cohort and 186 patients identified through a systematic review of 9 published studies. Our institutional cohort included 14 patients (12 females and 2 males) from 13 unrelated families diagnosed with DDX3X -syndrome, at a median age of 4.5 years (IQR 1.2–9.5). Echocardiogram was performed on nine patients, and cardiovascular abnormalities were found in 7 out of 9 patients who underwent echocardiography (78%), two of whom had major congenital heart defect (CHD) requiring surgical intervention. At the time of assessment, 13 individuals were still alive, while one had died at age six due to extracardiac complications. The systematic review included 9 studies involving 186 patients, of whom 32 (17.4%, 25 females and 7 males) had reported cardiovascular abnormalities, ranging from simple CHDs to more complex defects. Conclusion DDX3X -syndrome carries a significant cardiovascular burden, which is possibly higher than previously reported, including complex congenital heart disease requiring surgical repair. A thorough cardiovascular assessment, including an electrocardiogram and echocardiogram, should be universally recommended for all patients at the time of diagnosis.

Glutathione synthetase (GSS) deficiency is an extremely rare autosomal recessive inborn error of metabolism. This metabolic disorder is caused by mutations in the GSS gene, which encodes GSS—an enzyme that catalyses the ATP-dependent conversion of γ-glutamyl-cysteine and glycine to glutathione. Low glutathione impairs the cellular antioxidant defence mechanism, leaving cells susceptible to oxidative stress and damage.

PURPOSE Pharmacologic therapies for neurofibromatosis type 1-associated plexiform neurofibromas (NF1-PNs) are limited; currently, none are US Food and Drug Administration–approved for adults. METHODS ReNeu is an open-label, multicenter, pivotal, phase IIb trial of mirdametinib in 58 adults (≥18 years of age) and 56 children (2 to 17 years of age) with NF1-PN causing significant morbidities. Patients received mirdametinib capsules or tablets for oral suspension (2 mg/m 2 twice daily, maximum 4 mg twice daily), regardless of food intake, in 3 weeks on/1 week off 28-day cycles. The primary end point was confirmed objective response rate (ORR; proportion of patients with a ≥20% reduction of target PN volume from baseline on consecutive scans during the 24-cycle treatment phase) assessed by blinded independent central review (BICR) of volumetric magnetic resonance imaging. RESULTS Twenty-four of 58 adults (41%) and 29 of 56 children (52%) had a BICR-confirmed objective response during the 24-cycle treatment phase; in addition, two adults and one child had confirmed responses during long-term follow-up. Median (range) target PN volumetric best response was –41% (−90 to 13) in adults and –42% (−91 to 48) in children. Both cohorts reported significant and clinically meaningful improvement in patient- or parent proxy-reported outcome measures of worst tumor pain severity, pain interference, and health-related quality of life (HRQOL) that began early and were sustained during treatment. The most commonly reported treatment-related adverse events were dermatitis acneiform, diarrhea, and nausea in adults and dermatitis acneiform, diarrhea, and paronychia in children. CONCLUSION In ReNeu, the largest multicenter NF1-PN trial reported to date, mirdametinib treatment demonstrated significant confirmed ORRs by BICR, deep and durable PN volume reductions, and early, sustained, and clinically meaningful improvement in pain and HRQOL. Mirdametinib was well-tolerated in adults and children.

Background/Objectives: Pectus excavatum (PEx) is considered, at least partially, a familial disorder. A variety of inheritance patterns, associations with genetic syndromes, and pathogenic variants have been reported. However, the etiology of this condition is still not completely understood, and no known genes have been identified as definitive contributors. Methods: Family members with a confirmed PEx diagnosis (one proband and two first-degree relatives) and non-affected members were recruited into this study. Exome sequencing was performed on all affected familial PEx cases to systematically screen for candidate genes that are likely to be causative for PEx, and on non-affected family members for variant segregation analysis. Results: Ten families, with three affected members each, participated, providing thirty familial PEx cases. Different inheritance patterns were represented across the ten pedigrees, with possible incomplete penetrance. Genetic variants in REST (essential for neuronal development and associated with pectus deformities in prior studies), SMAD4 (variants can predispose individuals to thoracic aortic diseases), and COL5A (associated with Ehlers–Danlos syndrome and Fibromuscular dysplasia) were initially identified as potentially linked to the development of pectus deformities and segregated with the phenotype. No variants were shared across families in the studied population. Conclusions: Germline exome sequencing of families with multiple individuals affected by PEx in our study identified potential gene candidates linked to PEx. These candidates are private to individual families and no strong candidates shared across multiple families were identified. These findings suggest that the inheritance of PEx may not be strongly related to a shared single genetic variant in known genes. Given the accumulating evidence for the genetic basis of familial PEx, further studies, including polygenic analyses, as well as assessment of the non-coding genome and possible epigenetic markers are warranted.