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Santra S.,Birmingham Childrens Hospital | Cameron J.M.,Peter Gilgan Center for Research and Learning | Shyr C.,Child and Family Research Institute | Zhang L.,Child and Family Research Institute | And 11 more authors.
Molecular Genetics and Metabolism | Year: 2016

We report a patient from a consanguineous family who presented with transient acute liver failure and biochemical patterns suggestive of disturbed urea cycle and mitochondrial function, for whom conventional genetic and metabolic investigations for acute liver failure failed to yield a diagnosis. Whole exome sequencing revealed a homozygous 12-bp deletion in PCK1 (MIM 614168) encoding cytosolic phosphoenolpyruvate carboxykinase (PEPCK); enzymatic studies subsequently confirmed its pathogenic nature. We propose that PEPCK deficiency should be considered in the young child with unexplained liver failure, especially where there are marked, accumulations of TCA cycle metabolites on urine organic acid analysis and/or an amino acid profile with hyperammonaemia suggestive of a proximal urea cycle defect during the acute episode. If suspected, intravenous administration of dextrose should be initiated. Long-term management comprising avoidance of fasting with the provision of a glucose polymer emergency regimen for illness management may be sufficient to prevent future episodes of liver failure. This case report provides further insights into the (patho-)physiology of energy metabolism, confirming the power of genomic analysis of unexplained biochemical phenotypes. © 2016.


De Moulin D.,University of Western Ontario | Boulanger A.,University of Montréal | Clark A.J.,Dalhousie University | Clarke H.,University of Toronto | And 17 more authors.
Pain Research and Management | Year: 2014

BACKGROUND: Neuropathic pain (NeP), redefined as pain caused by a lesion or a disease of the somatosensory system, is a disabling condition that affects approximately two million Canadians. OBJECTIVE: To review the randomized controlled trials (RCTs) and systematic reviews related to the pharmacological management of NeP to develop a revised evidence-based consensus statement on its management. METHODS: RCTs, systematic reviews and existing guidelines on the pharmacological management of NeP were evaluated at a consensus meeting in May 2012 and updated until September 2013. Medications were recommended in the consensus statement if their analgesic efficacy was supported by at least one methodologically sound RCT (class I or class II) showing significant benefit relative to placebo or another relevant control group. Recommendations for treatment were based on the degree of evidence of analgesic efficacy, safety and ease of use. RESULTS: Analgesic agents recommended for first-line treatments are gabapentinoids (gabapentin and pregabalin), tricyclic antidepressants and serotonin noradrenaline reuptake inhibitors. Tramadol and controlled-release opioid analgesics are recommended as second-line treatments for moderate to severe pain. Cannabinoids are now recommended as third-line treatments. Recommended fourth-line treatments include methadone, anticonvulsants with lesser evidence of efficacy (eg, lamotrigine, lacosamide), tapentadol and botulinum toxin. There is support for some analgesic combinations in selected NeP conditions. CONCLUSIONS: These guidelines provide an updated, stepwise approach to the pharmacological management of NeP. Treatment should be individualized for each patient based on efficacy, side-effect profile and drug accessibility, including cost. Additional studies are required to examine head-to-head comparisons among analgesics, combinations of analgesics, long-term outcomes and treatment of pediatric, geriatric and central NeP. Copyright © Pulsus Group Inc.


PubMed | University of British Columbia, Peter Gilgan Center for Research and Learning, Radboud University Nijmegen, Birmingham Childrens Hospital and Child & Family Research Institute
Type: Case Reports | Journal: Molecular genetics and metabolism | Year: 2016

We report a patient from a consanguineous family who presented with transient acute liver failure and biochemical patterns suggestive of disturbed urea cycle and mitochondrial function, for whom conventional genetic and metabolic investigations for acute liver failure failed to yield a diagnosis. Whole exome sequencing revealed a homozygous 12-bp deletion in PCK1 (MIM 614168) encoding cytosolic phosphoenolpyruvate carboxykinase (PEPCK); enzymatic studies subsequently confirmed its pathogenic nature. We propose that PEPCK deficiency should be considered in the young child with unexplained liver failure, especially where there are marked, accumulations of TCA cycle metabolites on urine organic acid analysis and/or an amino acid profile with hyperammonaemia suggestive of a proximal urea cycle defect during the acute episode. If suspected, intravenous administration of dextrose should be initiated. Long-term management comprising avoidance of fasting with the provision of a glucose polymer emergency regimen for illness management may be sufficient to prevent future episodes of liver failure. This case report provides further insights into the (patho-)physiology of energy metabolism, confirming the power of genomic analysis of unexplained biochemical phenotypes.


PubMed | Peter Gilgan Center for Research and Learning, Hepatology and Nutrition, Hepatology and Nutrition., Kenya Medical Research Institute and 3 more.
Type: Journal Article | Journal: The American journal of clinical nutrition | Year: 2016

Diarrhea affects a large proportion of children with severe acute malnutrition (SAM). However, its etiology and clinical consequences remain unclear.We investigated diarrhea, enteropathogens, and systemic and intestinal inflammation for their interrelation and their associations with mortality in children with SAM.Intestinal pathogens (n = 15), cytokines (n = 29), fecal calprotectin, and the short-chain fatty acids (SCFAs) butyrate and propionate were determined in children aged 6-59 mo (n = 79) hospitalized in Malawi for complicated SAM. The relation between variables, diarrhea, and death was assessed with partial least squares (PLS) path modeling.Fatal subjects (n = 14; 18%) were younger (mean SD age: 17 11 compared with 25 11 mo; P = 0.01) with higher prevalence of diarrhea (46% compared with 18%, P = 0.03). Intestinal pathogens Shigella (36%), Giardia (33%), and Campylobacter (30%) predominated, but their presence was not associated with death or diarrhea. Calprotectin was significantly higher in children who died [median (IQR): 1360 mg/kg feces (2443-535 mg/kg feces) compared with 698 mg/kg feces (1438-244 mg/kg feces), P = 0.03]. Butyrate [median (IQR): 31 ng/mL (112-22 ng/mL) compared with 2036 ng/mL (5800-149 ng/mL), P = 0.02] and propionate [median (IQR): 167 ng/mL (831-131 ng/mL) compared with 3174 ng/mL (5819-357 ng/mL), P = 0.04] were lower in those who died. Mortality was directly related to high systemic inflammation (path coefficient = 0.49), whereas diarrhea, high calprotectin, and low SCFA production related to death indirectly via their more direct association with systemic inflammation.Diarrhea, high intestinal inflammation, low concentrations of fecal SCFAs, and high systemic inflammation are significantly related to mortality in SAM. However, these relations were not mediated by the presence of intestinal pathogens. These findings offer an important understanding of inflammatory changes in SAM, which may lead to improved therapies. This trial was registered at www.controlled-trials.com as ISRCTN13916953.


Schulze A.,Peter Gilgan Center for Research and Learning | Schulze A.,University of Toronto | Schulze A.,University of Toronto | Bauman M.,MassGeneral Hospital | And 15 more authors.
Pediatrics | Year: 2016

BACKGROUND AND OBJECTIVE: Creatine deficiency may play a role in the neurobiology of autism and may represent a treatable cause of autism. The goal of the study was to ascertain the prevalence of creatine deficiency syndromes (CDSs) in children with autism spectrum disorder (ASD). Methods: In a prospective multicenter study, 443 children were investigated after a confirmed diagnosis of ASD. Random spot urine screening for creatine metabolites (creatine, guanidinoacetate, creatinine, and arginine) with liquid chromatography-tandem mass spectrometry and second-tier testing with high-performance liquid chromatography methodology was followed by recall testing in 24-hour urines and confirmatory testing by Sanger-based DNA sequencing of GAMT, GATM, and SLC6A8 genes. Additional diagnostic tests included plasma creatine metabolites and in vivo brain proton magnetic resonance spectroscopy. The creatine metabolites in spot urine in the autism group were compared with 128 healthy controls controlled for age. Results: In 443 subjects with ASD investigated for CDS, we had 0 events (event: 0, 95% confidence interval 0-0.0068), therefore with 95% confidence the prevalence of CDS is <7 in 1000 children with ASD. The autism and control groups did not vary in terms of creatine metabolites (P >.0125) in urine. CONCLUSION Our study revealed a very low prevalence of CDS in children with nonsyndromic ASD and no obvious association between creatine metabolites and autism. Unlike our study population, we expect more frequent CDS among children with severe developmental delay, speech impairment, seizures, and movement disorders in addition to impairments in social communication, restricted interests, and repetitive behaviors. © 2016 by the American Academy of Pediatrics.


PubMed | Peter Gilgan Center for Research and Learning, Applied Genomics, The Hospital for Sick Children, Boston University and 4 more.
Type: Journal Article | Journal: Pediatrics | Year: 2016

Creatine deficiency may play a role in the neurobiology of autism and may represent a treatable cause of autism. The goal of the study was to ascertain the prevalence of creatine deficiency syndromes (CDSs) in children with autism spectrum disorder (ASD).In a prospective multicenter study, 443 children were investigated after a confirmed diagnosis of ASD. Random spot urine screening for creatine metabolites (creatine, guanidinoacetate, creatinine, and arginine) with liquid chromatography-tandem mass spectrometry and second-tier testing with high-performance liquid chromatography methodology was followed by recall testing in 24-hour urines and confirmatory testing by Sanger-based DNA sequencing of GAMT, GATM, and SLC6A8 genes. Additional diagnostic tests included plasma creatine metabolites and in vivo brain proton magnetic resonance spectroscopy. The creatine metabolites in spot urine in the autism group were compared with 128 healthy controls controlled for age.In 443 subjects with ASD investigated for CDS, we had 0 events (event: 0, 95% confidence interval 0-0.0068), therefore with 95% confidence the prevalence of CDS is <7 in 1000 children with ASD. The autism and control groups did not vary in terms of creatine metabolites (P > .0125) in urine.Our study revealed a very low prevalence of CDS in children with nonsyndromic ASD and no obvious association between creatine metabolites and autism. Unlike our study population, we expect more frequent CDS among children with severe developmental delay, speech impairment, seizures, and movement disorders in addition to impairments in social communication, restricted interests, and repetitive behaviors.


Budani M.,University of Toronto | Budani M.,Hospital for Sick Children | Mylvaganam M.,Hospital for Sick Children | Binnington B.,Hospital for Sick Children | And 2 more authors.
Journal of Lipid Research | Year: 2016

The biosynthesis of glucosylceramide (GlcCer) is a key rate-limiting step in complex glycosphingolipid (GSL) biosynthesis. To further define interacting partners of GlcCer, we have made a cleavable, biotinylated, photoreactive GlcCer analog in which the reactive nitrene is closely apposed to the GlcCer head group, by substituting the native fatty acid with d, l-2-aminohexadecanoic acid. Two amino-GlcCer diastereomer cross-linkers (XLA and XLB) were generated. XLB proved an effective lactosylceramide (LacCer) synthase substrate while XLA was inhibitory. Both probes specifically bound and cross-linked the GlcCer binding protein, glycolipid transfer protein (GLTP), but not other GSL binding proteins (Shiga toxin and cholera toxin). GlcCer inhibited GLTP cross-linking. Both GlcCer crosslinkers competed with microsomal nitrobenzoxadiazole (NBD)-GlcCer anabolism to NBD-LacCer. GLTP showed marked, ATP-dependent enhancement of cell-free intact microsomal LacCer synthesis from endogenous or exogenous liposomal GlcCer, supporting a role in the transport/ membrane translocation of cytosolic and extra-Golgi GlcCer. GLTP was specifically labeled by either XLA or XLB GlcCer cross-linker during this process, together with a (the same) small subset of microsomal proteins. These cross-linkers will serve to probe physiologically relevant GlcCer-interacting cellular proteins.-Budani, M., M. Mylvaganam, B. Binnington, and C. Lingwood. Synthesis of a novel photoactivatable glucosylceramide cross-linker. © 2016 by the American Society for Biochemistry and Molecular Biology, Inc.


Vol H.,The Hospital for Sick Children | Flank J.,The Hospital for Sick Children | Flank J.,University of Toronto | Lavoratore S.R.,Rideau Community Health Services | And 7 more authors.
Supportive Care in Cancer | Year: 2016

Purpose: Chemotherapy emetogenicity is the most important known determinant of chemotherapy-induced vomiting (CIV) in children. However, direct evidence regarding the emetogenic potential of chemotherapeutic agents in children is limited. This study describes the prevalence of complete control of acute and delayed phase chemotherapy-induced nausea and vomiting (CINV) in children receiving methotrexate. The prevalence of anticipatory CINV is described, and risk factors for CINV are explored. Methods: English-speaking children (4 to 18 years) receiving intermediate-dose (ID-MTX: >1 to <12 g/m2/dose) or high-dose methotrexate (HD-MTX: ≥12 g/m2/dose) participated in this prospective study. Emetic episodes, nausea severity, and antiemetic administration were documented for 24 h from the start of the methotrexate infusion (acute phase) and for up to a further 168 h (delayed phase). CINV prophylaxis was provided at the discretion of the treating physician. Anticipatory CINV was assessed in the 24 h preceding chemotherapy. Complete CINV control was defined as no emetic episodes and no nausea. Results: Thirty children (mean age, 11.8 ± 4 years; ID-MTX, 20; HD-MTX, 10) completed the study. CINV prophylaxis included the following: ondansetron/granisetron plus dexamethasone or nabilone. Few patients experienced complete CINV control (ID-MTX: acute phase 20 %, delayed phase 5 %; HD-MTX: acute phase 0 %, delayed phase 30 %). Complete emesis control was higher (ID-MTX: acute phase 70 %, delayed phase 50 %; HD-MTX: acute phase 70 %, delayed phase 60 %). Anticipatory CINV was reported by 6/28 patients (21 %). Patient age, sex, and history of motion sickness were not significant predictors of CINV. Conclusions: The poor complete CINV control rate in children receiving methotrexate confirms the classification of HD-MTX as highly emetogenic chemotherapy (HEC) and suggests that ID-MTX be reclassified as HEC. © 2015, Springer-Verlag Berlin Heidelberg.


Cameron J.M.,Peter Gilgan Center for Research and Learning | MacKay N.,University of Toronto | Feigenbaum A.,University of Toronto | Tarnopolsky M.,McMaster University | And 5 more authors.
European Journal of Paediatric Neurology | Year: 2015

Abstract Background Two siblings with hypertrophic cardiomyopathy and brain atrophy were diagnosed with Complex I deficiency based on low enzyme activity in muscle and high lactate/pyruvate ratio in fibroblasts. Methods Whole exome sequencing results of fibroblast gDNA from one sibling was narrowed down to 190 SNPs or In/Dels in 185 candidate genes by selecting non-synonymous coding sequence base pair changes that were not present in the SNP database. Results Two compound heterozygous mutations were identified in both siblings in NDUFV2, encoding the 24 kDa subunit of Complex I. The intronic mutation (c.IVS2 + 1delGTAA) is disease causing and has been reported before. The other mutation is novel (c.669-670insG, p.Ser224Valfs∗3) and predicted to cause a pathogenic frameshift in the protein. Subsequent investigation of 10 probands with complex I deficiency from different families revealed homozygosity for the intronic c.IVS2 + 1delGTAA mutation in a second, consanguineous family. In this family three of five siblings were affected. Interestingly, they presented with Leigh syndrome but no cardiac involvement. The same genotype had been reported previously in a two families but presenting with hypertrophic cardiomyopathy, trunk hypotonia and encephalopathy. Conclusion We have identified NDUFV2 mutations in two families with Complex I deficiency, including a novel mutation. The diagnosis of Leigh syndrome expands the clinical phenotypes associated with the c.IVS2 + 1delGTAA mutation in this gene. © 2015 European Paediatric Neurology Society.


PubMed | McMaster University, Peter Gilgan Center for Research and Learning and University of Toronto
Type: Case Reports | Journal: European journal of paediatric neurology : EJPN : official journal of the European Paediatric Neurology Society | Year: 2015

Two siblings with hypertrophic cardiomyopathy and brain atrophy were diagnosed with Complex I deficiency based on low enzyme activity in muscle and high lactate/pyruvate ratio in fibroblasts.Whole exome sequencing results of fibroblast gDNA from one sibling was narrowed down to 190 SNPs or In/Dels in 185 candidate genes by selecting non-synonymous coding sequence base pair changes that were not present in the SNP database.Two compound heterozygous mutations were identified in both siblings in NDUFV2, encoding the 24kDa subunit of Complex I. The intronic mutation (c.IVS2+1delGTAA) is disease causing and has been reported before. The other mutation is novel (c.669_670insG, p.Ser224Valfs*3) and predicted to cause a pathogenic frameshift in the protein. Subsequent investigation of 10 probands with complex I deficiency from different families revealed homozygosity for the intronic c.IVS2+1delGTAA mutation in a second, consanguineous family. In this family three of five siblings were affected. Interestingly, they presented with Leigh syndrome but no cardiac involvement. The same genotype had been reported previously in a two families but presenting with hypertrophic cardiomyopathy, trunk hypotonia and encephalopathy.We have identified NDUFV2 mutations in two families with Complex I deficiency, including a novel mutation. The diagnosis of Leigh syndrome expands the clinical phenotypes associated with the c.IVS2+1delGTAA mutation in this gene.

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