Heteroplasmic pathogenic m.12315G>A variant in MT-TL2 presenting with MELAS syndrome and depletion of nitric oxide donors

The MT-TL2 m.12315G>A pathogenic variant has previously been reported in five individuals with mild clinical phenotypes. Herein we report the case of a 5-year-old child with heteroplasmy for this variant who developed neurological regression and stroke-like episodes similar to those observed in mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). Biochemical evaluation revealed depletion of arginine on plasma amino acid analysis and low z-scores for citrulline on untargeted plasma metabolomics analysis. These findings suggested that decreased availability of nitric oxide may have contributed to the stroke-like episodes. The use of intravenous arginine during stroke-like episodes and daily enteral L-citrulline supplementation normalized her biochemical values of arginine and citrulline. Untargeted plasma metabolomics showed the absence of nicotinamide and 1-methylnicotinamide, and plasma total glutathione levels were low; thus, nicotinamide riboside and N-acetylcysteine therapies were initiated. This report expands the phenotype associated with the rare mitochondrial variant MT-TL2 m.12315G>A to include neurological regression and a MELAS-like phenotype. Individuals with this variant should undergo in-depth biochemical analysis to include untargeted plasma metabolomics, plasma amino acids, and glutathione levels to help guide a targeted approach to treatment.

NAXE deficiency: A neurometabolic disorder of NAD(P)HX repair amenable for metabolic correction

The NAD(P)HX repair system is a metabolite damage repair mechanism responsible for restoration of NADH and NADPH after their inactivation by hydration. Deficiency in either of its two enzymes, NAD(P)HX dehydratase (NAXD) or NAD(P)HX epimerase (NAXE), causes a fatal neurometabolic disorder characterized by decompensations precipitated by inflammatory stress. Clinical findings include rapidly progressive muscle weakness, ataxia, ophthalmoplegia, and motor and cognitive regression, while neuroimaging abnormalities are subtle or nonspecific, making a clinical diagnosis challenging. During stress, nonenzymatic conversion of NAD(P)H to NAD(P)HX increases, and in the absence of repair, NAD(P)H is depleted, and NAD(P)HX accumulates, leading to decompensation; however, the contribution of each to the metabolic derangement is not established. Herein, we summarize the clinical knowledge of NAXE deficiency from 30 cases and lessons learned about disease pathogenesis from cell cultures and model organisms and describe a metabolomics signature obtained by untargeted metabolomics analysis in one case at the time of crisis and after initiation of treatment. Overall, biochemical findings support a model of acute depletion of NAD⁺, signs of mitochondrial dysfunction, and altered lipidomics. These findings are further substantiated by untargeted metabolomics six months post-crisis showing that niacin supplementation reverses primary metabolomic abnormalities concurrent with improved clinical status.

ABCD1 and X-linked adrenoleukodystrophy: A disease with a markedly variable phenotype showing conserved neurobiology in animal models

X-linked adrenoleukodystrophy (X-ALD) is a phenotypically heterogeneous disorder involving defective peroxisomal β-oxidation of very long-chain fatty acids (VLCFAs), due to mutation in the ABCD1 gene. X-ALD is the most common peroxisomal inborn error of metabolism and confers a high degree of morbidity and mortality. Remarkably, a subset of patients exhibit a cerebral form with inflammatory invasion of the central nervous system and extensive demyelination, while in others only dying-back axonopathy or even isolated adrenal insufficiency is seen, without genotype-phenotype correlation. X-ALD's biochemical signature is marked elevation of VLCFAs in blood, a finding that has been utilized for massive newborn screening for early diagnosis. Investigational gene therapy approaches hold promises for improved outcomes. However, the pathophysiological mechanisms of the disease remain poorly understood, limiting investigation of targeted therapeutic options. Animal models for the disease recapitulate the biochemical signature of VLCFA accumulation and demonstrate mitochondrially generated reactive oxygen species, oxidative damage, increased glial death, and axonal damage. Most strikingly, however, cerebral invasion of leukocytes and demyelination were not observed in any animal model for X-ALD, reflecting upon pathological processes that are yet to be discovered. This review summarizes the current disease models in animals, the lessons learned from these models, and the gaps that remained to be filled in order to assist in therapeutic investigations for ALD.

A rare description of pure partial trisomy of 16q12.2q24.3 and review of the literature

Trisomy 16 is the most common autosomal trisomy in humans, which is almost uniformly embryonic lethal. Partial trisomy 16 including a segment of the long arm of chromosome 16 is occasionally compatible with life and has been associated with severe congenital defects, growth retardation, and early lethality. Segmental trisomy of 16q is usually described concomitantly with partial monosomy of another chromosome, often resulting from a parental balanced translocation. Pure partial chromosome 16q trisomy is exceedingly rare. About nine children with 16q12→qter and 16q13→qter duplication have been reported in the literature, almost all described with monosomy of a second chromosome, and highlighting very few long-term survivors. A single individual with pure partial distal 16q12.1q23.3 duplication has been reported in an infant, underscoring complexities of genetic counseling and management, especially in view of life-limiting congenital anomalies in rare survivors. Here, we present a 12-month-old child with pure 16q12.2q24.3 trisomy, having continued morbidity related to pulmonary hypertension and chronic lung disease. The features of intrauterine growth retardation, facial dysmorphism, hypotonia, congenital heart defect, distal contractures, urogenital abnormalities, and hearing loss support the association with 16q partial trisomy, as in previous studies. This report expands our current understanding related to the survival of infants with large segmental aneusomy of the long arm of chromosome 16.

Clinical variability in multifocal lymphangioendotheliomatosis with thrombocytopenia: a review of the literature

Multifocal lymphangioendotheliomatosis with thrombocytopenia (MLT) is a recently recognized disorder characterized by vascular lesions marked by distinct endothelial proliferation. Lesions affect multiple tissues, and MLT can be associated with refractory thrombocytopenia resulting in life-threatening bleeding. Diagnosing MLT may be challenging given its rarity and phenotypic variability. There is no consensus on the optimal management or treatment duration. We report a 4-month-old male who presented with multiple vascular malformations involving the gastrointestinal tract, lung, bones, choroid plexus, and spleen, with minimal cutaneous involvement and no thrombocytopenia. Wedge resection of a pulmonary nodule was strongly positive for lymphatic vessel endothelial hyaluronan receptor 1 favoring MLT despite the lack of thrombocytopenia. The patient's clinical symptoms and vascular lesions improved on sirolimus therapy. We review the literature to highlight the clinical variability of MLT and discuss the diagnostic and therapeutic options for MLT.

Clinical Utility of Genetic Testing in the Precision Diagnosis and Management of Pediatric Patients with Kidney and Urinary Tract Diseases

Background

As genetic testing increasingly integrates into the practice of nephrology, our understanding of the basis of many kidney disorders has exponentially increased. Given this, we recently initiated a Renal Genetics Clinic (RGC) at our large, urban children's hospital for patients with kidney disorders.

Methods

Genetic testing was performed in Clinical Laboratory Improvement Amendments-certified laboratories using single gene testing, multigene panels, chromosomal microarray, or exome sequencing.

Results

A total of 192 patients were evaluated in this clinic, with cystic kidney disease (49/192) being the most common reason for referral, followed by congenital anomalies of the kidney and urinary tract (41/192) and hematuria (38/192). Genetic testing was performed for 158 patients, with an overall diagnostic yield of 81 out of 158 (51%). In the 16 out of 81 (20%) of patients who reached a genetic diagnosis, medical or surgical treatment of the patients were affected, and previous clinical diagnoses were changed to more accurate genetic diagnoses in 12 of 81 (15%) patients.

Conclusions

Our genetic testing provided an accurate diagnosis for children and, in some cases, led to further diagnoses in seemingly asymptomatic family members and changes to overall medical management. Genetic testing, as facilitated by such a specialized clinical setting, thus appears to have clear utility in the diagnosis and counseling of patients with a wide range of kidney manifestations.

Overgrowth Syndromes-Evaluation, Diagnosis, and Management

Abnormally excessive growth results from perturbation of a complex interplay of genetic, epigenetic, and hormonal factors that orchestrate human growth. Overgrowth syndromes generally present with inherent health concerns and, in some instances, an increased risk of tumor predisposition that necessitate prompt diagnosis and appropriate referral. In this review, we introduce some of the more common overgrowth syndromes, along with their molecular mechanisms, diagnostics, and medical complications for improved recognition and management of patients affected with these disorders.

Corrigendum: Overgrowth Syndromes-Evaluation, Diagnosis, and Management

[This corrects the article DOI: 10.3389/fped.2020.574857.].

Use of Isotope-Edited FTIR to Derive a Backbone Structure of a Transmembrane Protein

Solving structures of membrane proteins has always been a formidable challenge, yet even upon success, the results are normally obtained in a mimetic environment that can be substantially different from a biological membrane. Herein, we use noninvasive isotope-edited FTIR spectroscopy to derive a structural model for the SARS coronavirus E protein transmembrane domain in lipid bilayers. Molecular-dynamics-based structural refinement, incorporating the IR-derived orientational restraints points to the formation of a helical hairpin structure. Disulfide cross-linking and X-ray reflectivity depth profiling provide independent support of the results. The unusually short helical hairpin structure of the protein might explain its ability to deform bilayers and is reminiscent of other peptides with membrane disrupting functionalities. Taken together, we show that isotope-edited FTIR is a powerful tool to analyze small membrane proteins in their native environment, enabling us to relate the unusual structure of the SARS E protein to its function.

Gaining insight into membrane protein structure using isotope-edited FTIR

FTIR spectroscopy has long been used as a tool used to gain average structural information on proteins. With the advent of stable isotope editing, FTIR can be used to derive accurate information on isolated amino acids. In particular, in an anisotropic sample such as membrane layers, it is possible to measure the orientation of the peptidic carbonyl groups. Herein, we review the theory that enables one to obtain accurate restraints from FTIR spectroscopy, alongside considerations for sample suitability and general applicability. We also propose approaches that may be used to generate structural models of simple membrane proteins based on FTIR orientational restraints. This article is part of a Special Issue entitled: FTIR in membrane proteins and peptide studies.

Environment Polarity in Proteins Mapped Noninvasively by FTIR Spectroscopy

The polarity pattern of a macromolecule is of utmost importance to its structure and function. For example, one of the main driving forces for protein folding is the burial of hydrophobic residues. Yet polarity remains a difficult property to measure experimentally, due in part to its non-uniformity in the protein interior. Herein, we show that FTIR linewidth analysis of noninvasive 1-(13)C=(18)O labels can be used to obtain a reliable measure of the local polarity, even in a highly multi-phasic system, such as a membrane protein. We show that in the Influenza M2 H(+) channel, residues that line the pore are located in an environment that is as polar as fully solvated residues, while residues that face the lipid acyl chains are located in an apolar environment. Taken together, FTIR linewidth analysis is a powerful, yet chemically non-perturbing approach to examine one of the most important properties in proteins - polarity.

Gating mechanism of the influenza A M2 channel revealed by 1D and 2D IR spectroscopies

The pH-controlled M2 protein from influenza A is a critical component of the virus and serves as a target for the aminoadamantane antiflu agents that block its H+ channel activity. To better understand its H+ gating mechanism, we investigated M2 in lipid bilayers with a new combination of IR spectroscopies and theory. Linear Fourier transform infrared (FTIR) spectroscopy was used to measure the precise orientation of the backbone carbonyl groups, and 2D infrared (IR) spectroscopy was used to identify channel-lining residues. At low pH (open state), our results match previously published solid-state NMR and X-ray structures remarkably well. However, at neutral pH when the channel is closed, our measurements indicate that a large conformational change occurs that is consistent with the transmembrane alpha-helices rotating by one amino acid register--a structural rearrangement not previously observed. The combination of simulations and isotope-labeled FTIR and 2D IR spectroscopies provides a noninvasive means of interrogating the structures of membrane proteins in general and ion channels in particular.

Disorder influence on linear dichroism analyses of smectic phases

Linear dichroism, the unequal absorption of parallel and perpendicular linear polarized light, is often used to determine the anisotropic ordering of rodlike polymers in a smectic phase, such as helices in a lipid bilayer. It is a measure of two properties of the sample: 1), orientation of the chromophore transition dipole moment (TDM) and 2), disorder. Since it is the orientation of the chromophore TDM that is needed for high resolution structural studies, it is imperative to either deconvolve sample disorder, or at a minimum, estimate its effect upon the calculated TDM orientation. Herein, a rigorous analysis of the effects of disorder is undertaken based on the recently developed Gaussian disorder model implemented in linear dichroism data. The calculation of both the rod tilt and rotational pitch angles as a function of the disorder and dichroism, yield the following conclusions: Disorders smaller than 5 degrees have a vanishingly small effect on the calculated polymer orientation, whereas values smaller than 10 degrees have a negligible effect on the calculated parameters. Disorders larger than 10 degrees have an appreciable effect on the calculated orientational parameters and as such must be estimated before any structural characterization. Finally the theory is tested on the HIV vpu transmembrane domain, employing experimental mosaicity measurements from x-ray reflectivity rocking scans and linear dichroism.

Measurement of day and night neutrino energy spectra at SNO and constraints on neutrino mixing parameters

The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged current events, assuming an undistorted 8B spectrum, the night minus day rate is 14.0%+/-6.3%(+1.5%)(-1.4%) of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the nu(e) asymmetry is found to be 7.0%+/-4.9%(+1.3%)(-1.2%). A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the large mixing angle solution.

Direct evidence for neutrino flavor transformation from neutral-current interactions in the Sudbury Neutrino Observatory

Observations of neutral-current nu interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and assuming the standard 8B shape, the nu(e) component of the 8B solar flux is phis(e) = 1.76(+0.05)(-0.05)(stat)(+0.09)(-0.09)(syst) x 10(6) cm(-2) s(-1) for a kinetic energy threshold of 5 MeV. The non-nu(e) component is phi(mu)(tau) = 3.41(+0.45)(-0.45)(stat)(+0.48)(-0.45)(syst) x 10(6) cm(-2) s(-1), 5.3sigma greater than zero, providing strong evidence for solar nu(e) flavor transformation. The total flux measured with the NC reaction is phi(NC) = 5.09(+0.44)(-0.43)(stat)(+0.46)(-0.43)(syst) x 10(6) cm(-2) s(-1), consistent with solar models.

Resolution of the pathways of poliovirus type 1 transmission during an outbreak

An outbreak of poliomyelitis with 20 cases occurred in Israel, Gaza, and the West Bank from October 1987 to October 1988. The wild type 1 poliovirus associated with the outbreak was most closely related to viruses found in the Nile Delta. The epidemiologic links among patients involved in the outbreak and patients with community-acquired infections during the outbreak were inferred from the evolutionary relationships among isolates of the outbreak virus. Complete VP1 sequences (906 nucleotides) were determined for 12 clinical and 4 sewage isolates. A total of 58 nucleotide differences were found among the 16 isolates; 74% of all substitutions were synonymous third-position transitions. An evolutionary tree, representing both the pathways of VP1 sequence evolution and the inferred chains of virus transmission during the outbreak, was constructed under the assumption that each substitution had occurred only once. The combined epidemiologic and molecular data suggest that a single founder strain was introduced into Israel from the vicinity of Gaza in the fall of 1987. Poliovirus circulation was apparently localized to southern communities during the winter and spread north by the following summer into the Hadera subdistrict of Israel, where it radiated via multiple chains of transmission into other communities in northern Israel and the West Bank. The close sequence matches (>99%) between clinical and sewage isolates from the same communities confirm the utility of environmental sampling as a tool for monitoring wild poliovirus circulation.

Multiple specificities of the staphylococcal and streptococcal fibronectin-binding microbial surface components recognizing adhesive matrix molecules

Many pathogenic gram-positive bacteria express fibronectin (Fn)-binding microbial surface components recognizing adhesive matrix molecules (MSCRAMMs), most of which have a similar structural organization with a primary ligand-binding domain consisting of 3-6 repeats of 40-50 amino-acid-residue motifs. The MSCRAMMs appear to preferentially bind to the N-terminal region of Fn, which is composed of five type-I modules. Here we report that the Fn-binding MSCRAMM FnbpA of Staphylococcus aureus contains a second ligand-binding domain located outside the repeat units. In addition, several sites in the Fn N-terminus presented as recombinant type-I module pairs bind to the repeat domain of the MSCRAMM. All of the MSCRAMMs analyzed, which include FnbpA of Staphylococcus aureus, Sfb of Streptococcus pyogenes, and FnbA and FnbB of Streptococcus dysgalactiae, were shown to bind to multiple sites in the N-terminal domain of Fn. By dissecting the repeat domain of FnbpA using synthetic peptides and recombinant fragments, we show that discrete, different motifs are responsible for the binding to individual sites in Fn, rather than a common motif being able to bind to several pairs of type-I Fn modules. The C-terminal half of many of the MSCRAMM repeat units contain a common motif, which is shown here to bind to the type-I module pair 4 and 5. In addition, some of the repeat units of FnbpA contain N-terminal motifs which bound to the type-I module pairs 1-2 and 2-3, respectively. These latter binding motifs appear to be partly overlapping and dependent on flanking sequences. Fluorescence polarization experiments using fluorescein-labeled MSCRAMM peptides and recombinant type-I Fn module pairs revealed dissociation constants of 1-13 microM. It was also shown that the fluorescein-labeled peptides differed in their primary binding sites on Fn.

Photodynamic inactivation of herpes viruses with phthalocyanine derivatives

The antiviral photosensitization capacity of 11 different phthalocyanine (Pc) derivatives was examined using herpes simplex virus-1, herpes simplex virus-2 and varicella zoster virus in the search for the most potent sensitizers for viral decontamination of blood. The kinetics of viral photoinactivation were resolved during the stages of viral adsorption and penetration into the host cells. The capacity of Pc in the photodynamic inactivation of viruses was compared with that of merocyanine 540 (MC540), another widely studied photosensitizer. Sensitivity to photoinactivation decreased progressively with time after addition of viruses to their host cells. The viruses were most sensitive to photodynamic inactivation up to 30 min from the initiation of adsorption. Cell-associated viruses, 45-60 min after the onset of adsorption, are highly resistant to photodynamic treatment by most photosensitizers, with the exception of amphiphilic Pc derivatives. Thus the mixed sulfonated Pc-naphthalocyanine derivatives AlNSB3P and AlN2SB2P demonstrated a remarkable decontamination activity even 60 min after the onset of adsorption. Ultrastructural examination of these photosensitized viruses demonstrated damage to the viral envelope which prevented viral adsorption and/or penetration. The non-enveloped adenovirus was found to be resistant to all the dyes tested.

Legionella longbeachae pneumonia in a patient splenectomized for hairy-cell leukemia

A 63-year-old man was admitted to the respiratory intensive care unit for pneumonia. Fifteen years earlier, hairy cell leukemia had been diagnosed and the patient underwent splenectomy. A clinical suspicion of legionellosis, later confirmed by both serology and isolation of the microorganism, prompted initiation of high dose erythromycin intravenously. The patient steadily deteriorated and passed away eight days later. This is the first reported case of hairy cell leukemia in which the diagnosis of Legionella longbeachae sero-group 1 infection was based on both serology and isolation.

Nodular malignant lymphoma presenting as bilateral adnexal masses

A case of nodular malignant lymphoma, small cleaved cell in both ovaries, tubes and peritubal tissue is reported in a 55-year-old nulliparous woman with primary clinical symptoms of dyspnea and chest pain. The disease was first diagnosed at laparotomy. The patient was treated by bilateral adnexectomy and chemotherapy. This is the third case of adnexal small cleaved cell nodular lymphoma reported in the literature. Clinical and pathological aspects of this relatively rare pathological entity are reviewed.

Detection of hepatitis A virus in sewage

Hepatitis A virus was found in the sewage of a town during an outbreak of hepatitis. The test for the presence of the virus in 50 ml sewage samples was carried out by affinity chromatography on an immunoadsorbent column followed by immune electron microscopy. The sewage samples were collected from several locations in the town. Hepatitis A virus was found only in a sample which was taken directly from the affected neighbourhood.

Evaluation of bone marrow granulocyte reserves in neutropenic and nonneutropenic Yemenite Jews

The bone marrow granulocyte reserves of 10 Yemenite Jews with hereditary neutropenia were estimated by measuring the maximum peripheral blood granulocyte increment after the administration of 40 mg prednisone. The control group consisted of 11 nonneutropenic Yemenites and 15 non-Yemenite Jews with normal peripheral blood neutrophil counts. The mean peripheral blood granulocyte increment in the neutropenic and nonneutropenic Yemenites was significantly less than in the non-Yemenite Jews. There was no significant difference in the response of the two Yemenite groups.

Acute lymphoblastic crisis in a patient with chronic lymphatic leukemia

A case of chronic lymphatic leukemia terminating in a lymphoblastic crisis is described. The small lymphocytes were demonstrated to be B cells, they carried immunoglobulins on their surface and formed EAC rosettes. The lymphoblasts had no immunoglobulins on their surface and only 18% of them formed EAC rosettes, none formed E rosettes. The lymphoblasts could be either immature B cells or Null cells.