Mitochondrial Protein Interaction Mapping Identifies Regulators of Respiratory Chain Function.

Mitochondria are essential for numerous cellular processes, yet hundreds of their proteins lack robust functional annotation. To reveal functions for these proteins (termed MXPs), we assessed condition-specific protein-protein interactions for 50 select MXPs using affinity enrichment mass spectrometry. Our data connect MXPs to diverse mitochondrial processes, including multiple aspects of respiratory chain function. Building upon these observations, we validated C17orf89 as a complex I (CI) assembly factor. Disruption of C17orf89 markedly reduced CI activity, and its depletion is found in an unresolved case of CI deficiency. We likewise discovered that LYRM5 interacts with and deflavinates the electron-transferring flavoprotein that shuttles electrons to coenzyme Q (CoQ). Finally, we identified a dynamic human CoQ biosynthetic complex involving multiple MXPs whose topology we map using purified components. Collectively, our data lend mechanistic insight into respiratory chain-related activities and prioritize hundreds of additional interactions for further exploration of mitochondrial protein function.

D-bifunctional protein deficiency caused by splicing variants in a neonate with severe peroxisomal dysfunction and persistent hypoglycemia.

D-bifunctional protein (DBP) deficiency is a rare, autosomal recessive peroxisomal enzyme deficiency resulting in a high burden of morbidity and early mortality. Patients with DBP deficiency resemble those with a severe Zellweger phenotype, with neonatal hypotonia, seizures, craniofacial dysmorphisms, psychomotor delay, deafness, blindness, and death typically within the first 2 years of life, although patients with residual enzyme function can survive longer. The clinical severity of the disease depends on the degree of enzyme deficiency. Loss-of-function variants typically result in no residual enzyme activity; however, splice variants may result in protein with residual function. We describe a full-term newborn presenting with hypotonia, seizures, and unexplained hypoglycemia, who was later found to have rickets at follow up. Rapid whole genome sequencing identified two HSD17B4 variants in trans; one likely pathogenic variant and one variant of uncertain significance (VUS) located in the polypyrimidine tract of intron 13. To determine the functional consequence of the VUS, we analyzed RNA from the patient's father with RNA-seq which showed skipping of Exon 14, resulting in a frameshift mutation three amino acids from the new reading frame. This RNA-seq analysis was correlated with virtually absent enzyme activity, elevated very-long-chain fatty acids in fibroblasts, and a clinically severe phenotype. Both variants are reclassified as pathogenic. Due to the clinical spectrum of DBP deficiency, this provides important prognostic information, including early mortality. Furthermore, we add persistent hypoglycemia to the clinical spectrum of the disease, and advocate for the early management of fat-soluble vitamin deficiencies to reduce complications.

Pediatricians' Reports of Interaction with Infant Formula Companies.

Introduction: Seventy percent of countries follow the World Health Organization International Code of Marketing Breast Milk Substitutes that prohibits infant formula companies (IFC) from providing free products to health care facilities, providing gifts to health care staff, or sponsoring meetings. The United States rejects this code, which may impact breastfeeding rates in certain areas. Objective: We aimed at gathering exploratory data about interactions between IFC and pediatricians. Methods: We distributed an electronic survey to U.S. pediatricians asking about practice demographics, interactions with IFC, and breastfeeding practices. Using the zip code of the practice, we obtained additional information from the 2018 American Communities Survey, including median income, percent of mothers who had graduated college, percent of mothers working, and racial and ethnic identity. We compared demographic data for those pediatricians who had a formula company representative visit versus not and those who had a sponsored meal versus not. Results: Of 200 participants, the majority reported a formula company representative visit to their clinic (85.5%) and receiving free formula samples (90%). Representatives were more likely to visit areas with higher-income patients (median = $100K versus $60K, p < 0.001). They tended to visit and sponsor meals for pediatricians at private practices and in suburban areas. Most of the reported conferences attended (64%) were formula company-sponsored. Conclusion: Interactions between IFC and pediatricians are prevalent and occur in many forms. Future studies may reveal whether these interactions influence the advice of pediatricians or the behavior of mothers who had planned to exclusively breastfeed.

Ethical considerations in the use of artificial womb/placenta technology.

Despite improvements in survival over the past few decades, pulmonary immaturity and the use of mechanical ventilation have stunted reduction in short- and long-term morbidities for infants at the borderline of viability (22-24 weeks of gestation). It has long been suspected that the use of an artificial womb or artificial placenta to preserve native fetal physiology and maintain fluid- rather than air-filled lungs would help to improve outcomes for these infants. As such, several institutions have ongoing efforts to develop this technology, bringing the field of neonatology within sight of clinical trials. Prior to use in humans, several important ethical issues should be considered and discussed, including the moral status of these patients and the term used to describe them, whether neonate, fetus, or another term entirely. These determinations will guide when it is appropriate to use the technology and when it is permissible to withdraw this support, as well as how to ascribe parental rights and the legal status of these patients.