Clinical and biochemical characterization of four patients with mutations in ECHS1

Short-chain enoyl-CoA hydratase (SCEH, encoded by ECHS1) catalyzes hydration of 2-trans-enoyl-CoAs to 3(S)-hydroxy-acyl-CoAs. SCEH has a broad substrate specificity and is believed to play an important role in mitochondrial fatty acid oxidation and in the metabolism of branched-chain amino acids. Recently, the first patients with SCEH deficiency have been reported revealing only a defect in valine catabolism. We investigated the role of SCEH in fatty acid and branched-chain amino acid metabolism in four newly identified patients. In addition, because of the Leigh-like presentation, we studied enzymes involved in bioenergetics. Metabolite, enzymatic, protein and genetic analyses were performed in four patients, including two siblings. Palmitate loading studies in fibroblasts were performed to study mitochondrial β-oxidation. In addition, enoyl-CoA hydratase activity was measured with crotonyl-CoA, methacrylyl-CoA, tiglyl-CoA and 3-methylcrotonyl-CoA both in fibroblasts and liver to further study the role of SCEH in different metabolic pathways. Analyses of pyruvate dehydrogenase and respiratory chain complexes were performed in multiple tissues of two patients. All patients were either homozygous or compound heterozygous for mutations in the ECHS1 gene, had markedly reduced SCEH enzymatic activity and protein level in fibroblasts. All patients presented with lactic acidosis. The first two patients presented with vacuolating leukoencephalopathy and basal ganglia abnormalities. The third patient showed a slow neurodegenerative condition with global brain atrophy and the fourth patient showed Leigh-like lesions with a single episode of metabolic acidosis. Clinical picture and metabolite analysis were not consistent with a mitochondrial fatty acid oxidation disorder, which was supported by the normal palmitate loading test in fibroblasts. Patient fibroblasts displayed deficient hydratase activity with different substrates tested. Pyruvate dehydrogenase activity was markedly reduced in particular in muscle from the most severely affected patients, which was caused by reduced expression of E2 protein, whereas E2 mRNA was increased. Despite its activity towards substrates from different metabolic pathways, SCEH appears to be only crucial in valine metabolism, but not in isoleucine metabolism, and only of limited importance for mitochondrial fatty acid oxidation. In severely affected patients SCEH deficiency can cause a secondary pyruvate dehydrogenase deficiency contributing to the clinical presentatio

Familial pulmonary alveolar proteinosis caused by mutations in CSF2RA

Primary pulmonary alveolar proteinosis (PAP) is a rare syndrome characterized by accumulation of surfactant in the lungs that is presumed to be mediated by disruption of granulocyte/macrophage colony-stimulating factor (GM-CSF) signaling based on studies in genetically modified mice. The effects of GM-CSF are mediated by heterologous receptors composed of GM-CSF binding (GM-CSF-Rα) and nonbinding affinity-enhancing (GM-CSF-Rβ) subunits. We describe PAP, failure to thrive, and increased GM-CSF levels in two sisters aged 6 and 8 yr with abnormalities of both GM-CSF-Rα–encoding alleles (CSF2RA). One was a 1.6-Mb deletion in the pseudoautosomal region of one maternal X chromosome encompassing CSF2RA. The other, a point mutation in the paternal X chromosome allele encoding a G174R substitution, altered an N-linked glycosylation site within the cytokine binding domain and glycosylation of GM-CSF-Rα, severely reducing GM-CSF binding, receptor signaling, and GM-CSF–dependent functions in primary myeloid cells. Transfection of cloned cDNAs faithfully reproduced the signaling defect at physiological GM-CSF concentrations. Interestingly, at high GM-CSF concentrations similar to those observed in the index patient, signaling was partially rescued, thereby providing a molecular explanation for the slow progression of disease in these children. These results establish that GM-CSF signaling is critical for surfactant homeostasis in humans and demonstrate that mutations in CSF2RA cause familial PAP

Pathogenic variants in glutamyl-tRNAGln amidotransferase subunits cause a lethal mitochondrial cardiomyopathy disorder.

Mitochondrial protein synthesis requires charging mt-tRNAs with their cognate amino acids by mitochondrial aminoacyl-tRNA synthetases, with the exception of glutaminyl mt-tRNA (mt-tRNAGln). mt-tRNAGln is indirectly charged by a transamidation reaction involving the GatCAB aminoacyl-tRNA amidotransferase complex. Defects involving the mitochondrial protein synthesis machinery cause a broad spectrum of disorders, with often fatal outcome. Here, we describe nine patients from five families with genetic defects in a GatCAB complex subunit, including QRSL1, GATB, and GATC, each showing a lethal metabolic cardiomyopathy syndrome. Functional studies reveal combined respiratory chain enzyme deficiencies and mitochondrial dysfunction. Aminoacylation of mt-tRNAGln and mitochondrial protein translation are deficient in patients' fibroblasts cultured in the absence of glutamine but restore in high glutamine. Lentiviral rescue experiments and modeling in S. cerevisiae homologs confirm pathogenicity. Our study completes a decade of investigations on mitochondrial aminoacylation disorders, starting with DARS2 and ending with the GatCAB complex

Primary and metastatic lung tumors in the pediatric population: a review and 25-year experience at a large children\u27s hospital.

CONTEXT: Primary lung neoplasms are rare in children, but they comprise a broad and interesting spectrum of lesions, some of which are familiar from other tissue sites, and some of which are unique to the pediatric lung. OBJECTIVE: To determine the relative incidence of primary and metastatic lung tumors in children and adolescents through a single-institution case series, to compare these data to reports in the medical literature, to discuss the clinical and pathologic features of primary tumors of the tracheobronchial tree and lung parenchyma in children, and to provide recommendations for handling pediatric lung cysts and tumors. DATA SOURCES: A 25-year single institutional experience with pediatric lung tumors, based on surgical biopsies and resections at Texas Children\u27s Hospital from June 1982 to May 2007, an additional 40 lung tumors referred in consultation, and a review of the medical literature. CONCLUSIONS: A total of 204 pediatric lung tumors were diagnosed at our institution, including 20 primary benign lesions (9.8%), 14 primary malignant lesions (6.9%), and 170 secondary lung lesions (83.3%). The ratio of primary benign to primary malignant to secondary malignant neoplasms is 1.4:1:11.6. The common types of lung cancer in adults are exceptional occurrences in the pediatric population. The most common primary lung malignancies in children are pleuropulmonary blastoma and carcinoid tumor. Other primary pediatric lung tumors include congenital peribronchial myofibroblastic tumor and other myofibroblastic lesions, sarcomas, carcinoma, and mesothelioma. Children with primary or acquired immunodeficiency are at risk for Epstein-Barr virus-related smooth muscle tumors, lymphoma, and lymphoproliferative disorders. Metastatic lung tumors are relatively common in children and also comprise a spectrum of neoplasia distinct from the adult population

Idiopathic Sclerosing Inflammation Presenting as Sinusitis

Idiopathic sclerosing orbital inflammation is a rare finding that is poorly delineated, immune mediated, and causes severe symptoms and disability. It has been described affecting the orbit in addition to other sites within the head and neck, but has rarely been described presenting as sinusitis. A case report and literature review were performed. A 14-year-old girl with right-sided face and eye pain and pressure for >1 month presented 3 days after endoscopic sinus surgery for presumed acute sinusitis. She subsequently developed ipsilateral vision loss and hypesthesia of the infraorbital nerve. MRI revealed a mildly enhancing soft tissue intensity lesion extending from the right maxillary sinus into the pterygopalatine fossa and orbital apex through the inferior orbital fissure. Biopsy specimens of the lesion were consistent with a sclerosing inflammatory lesion. High-dose steroids led to rapid improvement in vision and pain; however, the patient was unable to tolerate steroid weaning because of recurrence of eye pain and headache. Repeat imaging showed progression of the lesion. Rheumatology was consulted and the patient's steroid therapy was altered and her medications were expanded to include azathioprine. The patient's symptoms improved and subsequent imaging showed a reduction in the size and extent of the lesion. Idiopathic sclerosing inflammation is characterized by primary, chronic, and immunologically mediated fibrosis. Patients typically have a poor response to corticosteroid treatment or radiotherapy. Immunosuppressive therapy in addition to corticosteroids is the recommended treatment

Survival of an Infant with Homozygous Surfactant Protein C (SFTPC) Mutation

Lung diseases caused by surfactant protein C (SFTPC) mutations are inherited as autosomal traits with variable penetrance and severity or as sporadic disease caused by a de novo mutation on one allele. Here, we report the case of a child surviving with a homozygous surfactant protein C mutation after aggressive clinical management unlike his six siblings who died in infancy. This presentation raises the suspicion of an autosomal recessive inheritence that is discussed in this report. Pediatr Pulmonol. 2014; 49:E112-E115. (c) 2013 Wiley Periodicals, Inc