Progesterone for Neurodevelopment in Fetuses With Congenital Heart Defects: A Randomized Clinical Trial.

Importance: Neurodevelopmental outcomes for children with congenital heart defects (CHD) have improved minimally over the past 20 years. Objectives: To assess the feasibility and tolerability of maternal progesterone therapy as well as the magnitude of the effect on neurodevelopment for fetuses with CHD. Design, Setting, and Participants: This double-blinded individually randomized parallel-group clinical trial of vaginal natural progesterone therapy vs placebo in participants carrying fetuses with CHD was conducted between July 2014 and November 2021 at a quaternary care children's hospital. Participants included maternal-fetal dyads where the fetus had CHD identified before 28 weeks' gestational age and was likely to need surgery with cardiopulmonary bypass in the neonatal period. Exclusion criteria included a major genetic or extracardiac anomaly other than 22q11 deletion syndrome and known contraindication to progesterone. Statistical analysis was performed June 2022 to April 2024. Intervention: Participants were 1:1 block-randomized to vaginal progesterone or placebo by diagnosis: hypoplastic left heart syndrome (HLHS), transposition of the great arteries (TGA), and other CHD diagnoses. Treatment was administered twice daily between 28 and up to 39 weeks' gestational age. Main Outcomes and Measures: The primary outcome was the motor score of the Bayley Scales of Infant and Toddler Development-III; secondary outcomes included language and cognitive scales. Exploratory prespecified subgroups included cardiac diagnosis, fetal sex, genetic profile, and maternal fetal environment. Results: The 102 enrolled fetuses primarily had HLHS (n = 52 [50.9%]) and TGA (n = 38 [37.3%]), were more frequently male (n = 67 [65.7%]), and without genetic anomalies (n = 61 [59.8%]). The mean motor score differed by 2.5 units (90% CI, -1.9 to 6.9 units; P = .34) for progesterone compared with placebo, a value not statistically different from 0. Exploratory subgroup analyses suggested treatment heterogeneity for the motor score for cardiac diagnosis (P for interaction = .03) and fetal sex (P for interaction = .04), but not genetic profile (P for interaction = .16) or maternal-fetal environment (P for interaction = .70). Conclusions and Relevance: In this randomized clinical trial of maternal progesterone therapy, the overall effect was not statistically different from 0. Subgroup analyses suggest heterogeneity of the response to progesterone among CHD diagnosis and fetal sex. Trial Registration: ClinicalTrials.gov Identifier: NCT02133573.

Lmod2 is necessary for effective skeletal muscle contraction.

Muscle contraction is a regulated process driven by the sliding of actin-thin filaments over myosin-thick filaments. Lmod2 is an actin filament length regulator and essential for life since human mutations and complete loss of Lmod2 in mice lead to dilated cardiomyopathy and death. To study the little-known role of Lmod2 in skeletal muscle, we created a mouse model with Lmod2 expressed exclusively in the heart but absent in skeletal muscle. Loss of Lmod2 in skeletal muscle results in decreased force production in fast- and slow-twitch muscles. Soleus muscle from rescued Lmod2 knockout mice have shorter thin filaments, increased Lmod3 levels, and present with a myosin fiber type switch from fast myosin heavy chain (MHC) IIA to the slower MHC I isoform. Since Lmod2 regulates thin-filament length in slow-twitch but not fast-twitch skeletal muscle and force deficits were observed in both muscle types, this work demonstrates that Lmod2 regulates skeletal muscle contraction, independent of its role in thin-filament length regulation.

Efficient in vivo prime editing corrects the most frequent phenylketonuria variant, associated with high unmet medical need.

The c.1222C>T (p.Arg408Trp) variant in the phenylalanine hydroxylase gene (PAH) is the most frequent cause of phenylketonuria (PKU), the most common inborn error of metabolism. This autosomal-recessive disorder is characterized by accumulation of blood phenylalanine (Phe) to neurotoxic levels. Using real-world data, we observed that despite dietary and medical interventions, most PKU individuals harboring at least one c.1222C>T variant experience chronic, severe Phe elevations and do not comply with Phe monitoring guidelines. Motivated by these findings, we generated an edited c.1222C>T hepatocyte cell line and humanized c.1222C>T mouse models, with which we demonstrated efficient in vitro and in vivo correction of the variant with prime editing. Delivery via adeno-associated viral (AAV) vectors reproducibly achieved complete normalization of blood Phe levels in PKU mice, with up to 52% whole-liver corrective PAH editing. These studies validate a strategy involving prime editing as a potential treatment for a large proportion of individuals with PKU.

The Importance of Succinylacetone: Tyrosinemia Type I Presenting with Hyperinsulinism and Multiorgan Failure Following Normal Newborn Screening.

Tyrosinemia type 1 (TT1) is an inborn error of tyrosine metabolism with features including liver dysfunction, cirrhosis, and hepatocellular carcinoma; renal dysfunction that may lead to failure to thrive and bone disease; and porphyric crises. Once fatal in most infantile-onset cases, pre-symptomatic diagnosis through newborn screening (NBS) protocols, dietary management, and pharmacotherapy with nitisinone have improved outcomes. Succinylacetone provides a sensitive and specific marker for the detection of TT1 but is not universally utilized in screening protocols for the disease. Here, we report an infant transferred to our facility for evaluation and management of hyperinsulinism who subsequently developed acute-onset liver, respiratory, and renal failure around one month of life. She was found to have TT1 caused by novel pathogenic variant in fumarylacetoacetate hydrolase (c.1014 delC, p.Cys 338 Ter). Her NBS, which utilized tyrosine as a primary marker, had been reported as normal, with a tyrosine level of 151 µmol/L (reference: < 280 µmol/L). Retrospective analysis of dried blood spot samples via tandem mass spectrometry showed detectable succinylacetone ranging 4.65-10.34 µmol/L. To our knowledge, this is the first patient with TT1 whose initial presenting symptom was hyperinsulinemic hypoglycemia. The case highlights the importance of maintaining a high suspicion for metabolic disease in critically ill children, despite normal NBS. We also use the case to advocate for NBS for TT1 using succinylacetone quantitation.

Multiple Sulfatase Deficiency: A Disease Comprising Mucopolysaccharidosis, Sphingolipidosis, and More Caused by a Defect in Posttranslational Modification.

Multiple sulfatase deficiency (MSD, MIM #272200) is an ultra-rare disease comprising pathophysiology and clinical features of mucopolysaccharidosis, sphingolipidosis and other sulfatase deficiencies. MSD is caused by impaired posttranslational activation of sulfatases through the formylglycine generating enzyme (FGE) encoded by the sulfatase modifying factor 1 (SUMF1) gene, which is mutated in MSD. FGE is a highly conserved, non-redundant ER protein that activates all cellular sulfatases by oxidizing a conserved cysteine in the active site of sulfatases that is necessary for full catalytic activity. SUMF1 mutations result in unstable, degradation-prone FGE that demonstrates reduced or absent catalytic activity, leading to decreased activity of all sulfatases. As the majority of sulfatases are localized to the lysosome, loss of sulfatase activity induces lysosomal storage of glycosaminoglycans and sulfatides and subsequent cellular pathology. MSD patients combine clinical features of all single sulfatase deficiencies in a systemic disease. Disease severity classifications distinguish cases based on age of onset and disease progression. A genotype- phenotype correlation has been proposed, biomarkers like excreted storage material and residual sulfatase activities do not correlate well with disease severity. The diagnosis of MSD is based on reduced sulfatase activities and detection of mutations in SUMF1. No therapy exists for MSD yet. This review summarizes the unique FGE/ sulfatase physiology, pathophysiology and clinical aspects in patients and their care and outlines future perspectives in MSD.