Congenital Disorders of Glycosylation in Portugal-Two Decades of Experience

OBJECTIVE

To describe the clinical, biochemical, and genetic features of both new and previously reported patients with congenital disorders of glycosylation (CDGs) diagnosed in Portugal over the last 20 years.

STUDY DESIGN

The cohort includes patients with an unexplained multisystem or single organ involvement, with or without psychomotor disability. Serum sialotransferrin isoforms and, whenever necessary, apolipoprotein CIII isoforms and glycan structures were analyzed. Additional studies included measurement of phosphomannomutase (PMM) activity and analysis of lipid-linked oligosaccharides in fibroblasts. Sanger sequencing and massive parallel sequencing were used to identify causal variants or the affected gene, respectively.

RESULTS

Sixty-three individuals were diagnosed covering 14 distinct CDGs; 43 patients diagnosed postnatally revealed a type 1, 14 a type 2, and 2 a normal pattern on serum transferrin isoelectrofocusing. The latter patients were identified by whole exome sequencing. Nine of them presented also a hypoglycosylation pattern on apolipoprotein CIII isoelectrofocusing, pointing to an associated O-glycosylation defect. Most of the patients (62%) are PMM2-CDG and the remaining carry pathogenic variants in ALG1, ATP6AP1, ATP6AP2, ATP6V0A2, CCDC115, COG1, COG4, DPAGT1, MAN1B1, SLC35A2, SRD5A3, RFT1, or PGM1.

CONCLUSIONS

Portuguese patients with CDGs are presented in this report, some of them showing unique clinical phenotypes. Among the 14 genes mutated in Portuguese individuals, 8 are shared with a previously reported Spanish cohort. However, regarding the mutational spectrum of PMM2-CDG, the most frequent CDG, a striking similarity between the 2 populations was found, as only 1 mutated allele found in the Portuguese group has not been reported in Spain.

Pyruvate dehydrogenase complex deficiency: updating the clinical, metabolic and mutational landscapes in a cohort of Portuguese patients

BACKGROUND

The pyruvate dehydrogenase complex (PDC) catalyzes the irreversible decarboxylation of pyruvate into acetyl-CoA. PDC deficiency can be caused by alterations in any of the genes encoding its several subunits. The resulting phenotype, though very heterogeneous, mainly affects the central nervous system. The aim of this study is to describe and discuss the clinical, biochemical and genotypic information from thirteen PDC deficient patients, thus seeking to establish possible genotype-phenotype correlations.

RESULTS

The mutational spectrum showed that seven patients carry mutations in the PDHA1 gene encoding the E1α subunit, five patients carry mutations in the PDHX gene encoding the E3 binding protein, and the remaining patient carries mutations in the DLD gene encoding the E3 subunit. These data corroborate earlier reports describing PDHA1 mutations as the predominant cause of PDC deficiency but also reveal a notable prevalence of PDHX mutations among Portuguese patients, most of them carrying what seems to be a private mutation (p.R284X). The biochemical analyses revealed high lactate and pyruvate plasma levels whereas the lactate/pyruvate ratio was below 16; enzymatic activities, when compared to control values, indicated to be independent from the genotype and ranged from 8.5% to 30%, the latter being considered a cut-off value for primary PDC deficiency. Concerning the clinical features, all patients displayed psychomotor retardation/developmental delay, the severity of which seems to correlate with the type and localization of the mutation carried by the patient. The therapeutic options essentially include the administration of a ketogenic diet and supplementation with thiamine, although arginine aspartate intake revealed to be beneficial in some patients. Moreover, in silico analysis of the missense mutations present in this PDC deficient population allowed to envisage the molecular mechanism underlying these pathogenic variants.

CONCLUSION

The identification of the disease-causing mutations, together with the functional and structural characterization of the mutant protein variants, allow to obtain an insight on the severity of the clinical phenotype and the selection of the most appropriate therapy.

FRI0274 HISTORY OF BIOLOGICS AND FEMALE GENDER ARE LINKED TO GOLIMUMAB DISCONTINUATION IN AXIAL SPONDYLOARTHRITIS: A SUB-ANALYSIS OF THE GO-PRACTICE STUDY

Background:

Golimumab (GLM) is the latest anti-TNFα to be indicated for treating rheumatoid arthritis (RA), psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA). The GO-PRACTICE study was performed in France at the request of the French Health Authorities, for the reevaluation of GLM in real-life.

Objectives:

The primary objective was to estimate GLM persistence at 2 years from initial prescription. This abstract focuses on a post-hoc analysis of the factors linked to GLM discontinuation in axSpA patients.

Methods:

Observational, prospective, multicenter study, that consecutively recruited adult patients with RA, PsA and axSpA who were newly prescribed GLM. Patients were followed-up for 2 years and outcomes data were collected at baseline (BL), 1 and 2 years. Patients’ sociodemographic characteristics, disease history, comorbidities and treatment history were also collected at BL. Persistence was estimated with the Kaplan-Meier method. Cox proportional hazard models were used to assess factors associated with persistence. Selected BL characteristics were studied in univariate models, where those associated withp-value <0.20 were included in multivariate analysis. Significance level was set atp<0.05.

Results:

478 patients with axSpA were included from Jan 2015 to Mar 2016. Mean age was 43 years and 55% were female; 61% of patients were biologic-naïve (BN, n=291) and 39% (n=187) were biologic-pretreated (BP). Median time-elapsed in years since axSpA diagnosis was 1.7 (range 0–45.1) and 6.9 (range 0.2–51.8) in BN and BP patients, respectively (P<0.001); 97% patients were prescribed 50 mg GLM monthly and co-treatments included DMARD (34%), corticosteroids (17%) and NSAIDs/analgesics (90%).

Cumulative persistence probability of GLM at 2-years was 52.6% (Fig 1). Table 1 details the binary variables associated with GLM discontinuation atp<0.20. Among continuous variables, BL CRP level was associated withp<0.20. A multivariate analysis of these factors revealed that being female (HR 1.92, 95%CI 1.43–2.56,P<0.001) and being BP (HR 1.45, 95%CI (1.11–1.90),P=0.007) were risk factors for GLM discontinuation (Table 1).

Table 1.

Logistic model results for variables of interest and their link to GLM discontinuation in axSpA

FactorModalitiesχ2(p)Hazard ratio (HR)95% CIHR following univariate analysis (p>0.20)AgeContinuous variable0.5201.000.99–1.02Disease duration0.4011.010.99–1.03Inflammatory bowel diseaseYes vs. No0.2770.740.43–1.28Gastrointestinal disease0.3441.270.78–2.06Uveitis0.2370.800.55–1.16Psoriasis0.2380.920.64–1.31     HR following multivariate analysis (variables with p<0.20 at univariate analysis)GenderFemale vs. Male< 0.0011.921.43–2.56Biologics historyPretreated vs. naïve0.0071.451.11–1.90Serum CRPContinuous variable0.1770.990.98–1.00DMARD historyYes vs. No0.0621.370.99–1.90Ongoing corticosteroids0.6931.080.73–1.61Anemia0.1701.820.78–4.24Kidney Disease0.5081.500.45–4.97Other physical illness0.4351.280.69–2.34

Conclusion:

2-year GLM persistence in axSpA patients was 52.6%. Females and those who were biologics-pretreated were at greater risk for discontinuing GLM before 2 years.

Disclosure of Interests:

Philippe Bertin Consultant of: MSD France, Philippe Goupille Grant/research support from: AbbVie, Amgen, Biogen, BMS, Celgene, Chugai, Lilly, Janssen, Medac, MSD France, Nordic Pharma, Novartis, Pfizer, Sanofi and UCB, Consultant of: AbbVie, Amgen, Biogen, BMS, Celgene, Chugai, Lilly, Janssen, Medac, MSD France, Nordic Pharma, Novartis, Pfizer, Sanofi and UCB, Speakers bureau: AbbVie, Amgen, Biogen, BMS, Celgene, Chugai, Lilly, Janssen, Medac, MSD France, Nordic Pharma, Novartis, Pfizer, Sanofi and UCB, Florence Tubach Grant/research support from: Florence TUBACH is head of the Centre de Pharmacoépidémiologie (Cephepi) of the Assistance Publique – Hôpitaux de Paris and of the Clinical Research Unit of Pitié-Salpêtrière hospital, both these structures have received research funding, grants and fees for consultant activities from a large number of pharmaceutical companies, that have contributed indiscriminately to the salaries of its employees. Florence Tubach didn’t receive any personal remuneration from these companies., Eric Lespessailles Consultant of: Amgen, Celgene, Lilly, MSD France, Novartis, UCB, Speakers bureau: Amgen, Celgene, Lilly, MSD France, Novartis, UCB, Naoual HARID Employee of: MSD France, Saannya Sequeira Consultant of: MSD France, Jean-Marie Fayette Consultant of: MSD France, Bruno Fautrel Grant/research support from: AbbVie, Lilly, MSD, Pfizer, Consultant of: AbbVie, Biogen, BMS, Boehringer Ingelheim, Celgene, Lilly, Janssen, Medac MSD France, Nordic Pharma, Novartis, Pfizer, Roche, Sanofi Aventis, SOBI and UCB, René-Marc Flipo Consultant of: Johnson and Johnson, MSD France, Novartis, Sanofi, Speakers bureau: Johnson and Johnson, MSD France, Novartis, Sanofi

Early-childhood social reticence predicts SCR-BOLD coupling during fear extinction recall in preadolescent youth

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Threat circuit function may develop differently in children with different temperamental profiles, such as high vs. low social reticence.

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We relate individual differences in longitudinally assessed, observed socially reticent behavior to brain-physiology interactions during extinction recall.

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Childhood social reticence predicts a distinct pattern of hemodynamic-autonomic covariation when recalling extinguished threat and safety cues.

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Covariation patterns indicated that socially reticent youth had difficulty tracking safety as a function of stimulus resemblance to the safe stimulus.

Social Reticence (SR) is a temperament construct identified in early childhood that is expressed as shy, anxiously avoidant behavior and, particularly when stable, robustly associated with risk for anxiety disorders. Threat circuit function may develop differently for children high on SR than low on SR. We compared brain function and behavior during extinction recall in a sample of 11-to-15-year-old children characterized in early childhood on a continuum of SR. Three weeks after undergoing fear conditioning and extinction, participants completed a functional magnetic resonance imaging extinction recall task assessing memory and threat differentiation for conditioned stimuli. Whereas self-report and psychophysiological measures of differential conditioning, extinction, and extinction recall were largely similar across participants, SR-related differences in brain function emerged during extinction recall. Specifically, childhood SR was associated with a distinct pattern of hemodynamic-autonomic covariation in the brain when recalling extinguished threat and safety cues. SR and attention focus impacted associations between trial-by-trial variation in autonomic responding and in brain activation. These interactions occurred in three main brain areas: the anterior insular cortex (AIC), the anterior subdivision of the medial cingulate cortex (aMCC), and the dorsolateral prefrontal cortex (dlPFC). This pattern of SCR-BOLD coupling may reflect selective difficulty tracking safety in a temperamentally at-risk population.

Atypical adult-onset methylmalonic acidemia and homocystinuria presenting as hemolytic uremic syndrome

Thrombotic microangiopathy (TMA) syndromes can be secondary to a multitude of different diseases. Most can be identified with a systematic approach and, when excluded, TMA is generally attributed to a dysregulation in the activity of the complement alternative pathways-atypical hemolytic uremic syndrome (aHUS). We present a challenging case of a 19-year-old woman who presented with thrombotic microangiopathy, which was found to be caused by methylmalonic acidemia and homocystinuria, a rare vitamin B12 metabolism deficiency. To our knowledge, this is the first time that an adult-onset methylmalonic acidemia and homocystinuria presents as TMA preceding CNS involvement.

MEGDEL Syndrome: Expanding the Phenotype and New Mutations

3-MEthylGlutaconic aciduria, Deafness, Encephalopathy, neuroradiological evidence of Leigh-like disease (MEGDEL syndrome) was initially described in four children with additional features of defective oxidative phosphorylation. Loss of functional variants in the SERAC1 gene was later reported in relation with this disorder of phospholipid remodeling. We describe a girl born after a pregnancy complicated by intrauterine growth retardation. In the neonatal period, she presented hypotonia, lethargy, weak reflexes, transient hypoglycemia, and elevated transaminases. Magnetic resonance imaging (MRI) performed at 12 days of life showed bilateral basal ganglia alterations suggestive of Leigh syndrome. She progressed with failure to thrive, severe delay of developmental milestones, axial hypotonia, spastic tetraparesis and dystonic movements. Investigations disclosed hyperlactacidemia, and the urinary organic acids revealed high levels mainly of 3-methylglutaconic acid. Muscle biopsy showed decreased activity of several complexes of the respiratory chain. Compound heterozygosity for two previously unreported variants in SERAC1 leads to the diagnosis of MEGDEL syndrome. Unlike other patients, this child presents very early MRI alterations and manifests no deafness.

Hyperprolinemia as a clue in the diagnosis of a patient with psychiatric manifestations

Lately, microdeletions of the 22q region, responsible for DiGeorge syndrome or velocardiofacial syndrome, have been increasingly related to neuropsychiatric disorders including schizophrenia and bipolar disorder. These manifestations seem to be related to certain genes located in the hemideleted region such as the proline dehydrogenase (PRODH) and the catechol-o-methyltransferase (COMT) genes. We describe a teenager who started his adolescent psychiatric care presenting cognitive impairment, irritable mood and aggressive behaviour with schizophrenia-like symptoms that scored 153 in the Positive and Negative Symptoms Scale (PANSS) assessment. Worsening of symptoms when the patient was treated with valproic acid, and plasma aminoacids showing an increase in alanine and proline, suggested a mitochondrial involvement of the proline metabolic pathway. Mild dysmorphic features also suggested a possible 22q11 deletion syndrome that was confirmed. A mutation for Hyperprolinemia type I was also detected. Knowledge of the correct diagnosis was crucial for an adequate treatment.

Whole exome sequencing identifies multiple diagnoses in congenital glaucoma with systemic anomalies

The genetic basis of congenital glaucoma with systemic anomalies is largely unknown. Whole exome sequencing (WES) in 10 probands with congenital glaucoma and variable systemic anomalies identified pathogenic or likely pathogenic variants in three probands; in two of these, a combination of two Mendelian disorders was found to completely explain the patients' features whereas in the third case only the ocular findings could be explained by the genetic diagnosis. The molecular diagnosis for glaucoma included two cases with compound heterozygous or homozygous pathogenic alleles in CYP1B1 and one family with a dominant pathogenic variant in FOXC1; the second genetic diagnosis for the additional systemic features included compound heterozygous mutations in NPHS1 in one family and a heterozygous 18q23 deletion in another pedigree. These findings show the power of WES in the analysis of complex conditions and emphasize the importance of CYP1B1 screening in patients with congenital glaucoma regardless of the presence/absence of other systemic anomalies.

Increasing the sensitivity for stem cell monitoring in system-function based magnetic particle imaging

The use of superparamagnetic iron oxide nanoparticles (SPIONs) has provided new possibilities in biophysics and biomedical imaging technologies. The magnetization dynamics of SPIONs, which can be influenced by the environment, are of central interest. In this work, different biological SPION environments are used to investigate three different calibration methods for stem cell monitoring in magnetic particle imaging. It is shown that calibrating using SPIONs immobilized via agarose gel or intracellular uptake results in superior stem cell image quality compared to mobile SPIONs in saline. This superior image quality enables more sensitive localization and identification of a significantly smaller number of magnetically labeled stem cells. The results are important for cell tracking and monitoring of future SPION based therapies such as hyperthermia based cancer therapies, targeted drug delivery, or tissue regeneration approaches where it is crucial to image a sufficiently small number of SPIONs interacting with biological matter.

Sulfite oxidase deficiency--an unusual late and mild presentation

INTRODUCTION

Sulfite oxidase deficiency (SOD) is an autosomal recessive inherited disease usually presenting in the neonatal period with severe neurological symptoms including seizures, often refractory to anticonvulsant therapy, and a rapidly progressive encephalopathy resembling neonatal hypoxic ischemia, with premature death. Most patients develop dislocated ocular lenses. Later or milder presentations of SOD are being reported with increasing frequency. These presentations include neurological regression with loss of previously acquired milestones or movement disorders.

CASE REPORT

We report a four years old girl presenting with intermittent ataxia and uncoordinated limb movements. A similar episode of ataxia had occurred previously, one year before, with complete neurologic recovery and normal developmental milestones. Bilateral lens dislocation had been recently diagnosed. Cranial MRI demonstrated bilateral globus pallidus enhancement. Low homocysteine was found in plasma and Sulfitest(R) was positive. Further investigations led to confirmation of isolated sulfite oxidase deficiency with no enzyme activity detected on skin fibroblasts culture.

DISCUSSION

This case illustrates the clinical variability of SOD and it is not only atypical but also seems to be the mildest form described so far. The association of ectopia lentis with a movement disorder, even without psychomotor regression, should prompt us to look for this diagnosis.

A frequent splicing mutation and novel missense mutations color the updated mutational spectrum of classic galactosemia in Portugal

Classic galactosemia is an autosomal recessive disorder caused by deficient galactose-1-phosphate uridylyltransferase (GALT) activity. Patients develop symptoms in the neonatal period, which can be ameliorated by dietary restriction of galactose. Many patients develop long-term complications, with a broad range of clinical symptoms whose pathophysiology is poorly understood. The high allelic heterogeneity of GALT gene that characterizes this disorder is thought to play a determinant role in biochemical and clinical phenotypes. We aimed to characterize the mutational spectrum of GALT deficiency in Portugal and to assess potential genotype-phenotype correlations. Direct sequencing of the GALT gene and in silico analyses were employed to evaluate the impact of uncharacterized mutations upon GALT functionality. Molecular characterization of 42 galactosemic Portuguese patients revealed a mutational spectrum comprising 14 nucleotide substitutions: ten missense, two nonsense and two putative splicing mutations. Sixteen different genotypic combinations were detected, half of the patients being p.Q188R homozygotes. Notably, the second most frequent variation is a splicing mutation. In silico predictions complemented by a close-up on the mutations in the protein structure suggest that uncharacterized missense mutations have cumulative point effects on protein stability, oligomeric state, or substrate binding. One splicing mutation is predicted to cause an alternative splicing event. This study reinforces the difficulty in establishing a genotype-phenotype correlation in classic galactosemia, a monogenic disease whose complex pathogenesis and clinical features emphasize the need to expand the knowledge on this "cloudy" disorder.

Incidence of maple syrup urine disease in Portugal

Maple syrup urine disease is an autosomal recessive disorder of branched-chain amino acids metabolism with a worldwide frequency of 1/185,000 live newborns. In Portugal, the incidence of the disease has not been assessed. Based on the review of the cases diagnosed by tandem mass spectrometry an incidence of 1/86,800 live newborns was estimated in Portugal, indicating that the disease is more frequent in this country than reported in most populations.

Molecular and structural analyses of maple syrup urine disease and identification of a founder mutation in a Portuguese Gypsy community

Maple syrup urine disease (MSUD) is an autosomal recessive disorder, caused by the defective function of the branched-chain alpha-ketoacid dehydrogenase complex (BCKD). BCKD is a mitochondrial complex, encoded by four nuclear genes (BCKDHA, BCKDHB, DBT and DLD), involved in the metabolism of branched-chain amino acids (BCAAs). Since the MSUD mutational spectrum has not been previously assessed in Portugal, in this study we present the molecular characterization of 30 MSUD Portuguese patients. Seventeen putative mutations have been identified (six in BCKDHA, five in BCKDHB and six in DBT); seven of them are here described for the first time. The most common mutation identified was a C deletion in BCKDHA gene (c.117delC; p.R40GfsX23), already reported in the Spanish population. Interestingly, it was found in all patients of a Gypsy community from South of the country, so a founder effect is probably responsible for the high incidence of the disease in this community. Structural models of MSUD missense mutations have been performed to understand their pathogenic effect, in order to elucidate and often to predict the severity of a mutation clinical consequence.

Spectrum of MMACHC mutations in Italian and Portuguese patients with combined methylmalonic aciduria and homocystinuria, cblC type

Methylmalonic aciduria (MMA) and homocystinuria, cblC type (MIM 277400) is the most frequent inborn error of vitamin B(12). The recent identification of the disease gene, MMACHC, has permitted preliminary genotype-phenotype correlations. We studied 24 Italian and 17 Portuguese patients with cblC defect to illustrate the spectrum of mutations in a southern European population and discuss the impact that mutation identification has on routine diagnostic procedures. Since the metabolic defect raises the serum levels of homocysteine, we also tested if variants in MTHFR-playing a key role in homocysteine remethylation pathway-could act as genetic modifier in cblC defect. We found that the c.271dupA (accounting for 55% of the MMACH alleles in our cohort) followed by c.394C>T (16%) and c.331C>T (9%) were the most frequent mutations. In our study we also identified a novel mutation (c.544T>C). On the other hand, the MTHFR genotype did not appear to influence age at onset, the clinical phenotype and outcome of patients with cblC defect. This study shows that mutation screening for the most common MMACH mutations occurring in early-onset forms (c.271dupA and c.331C>T) seems to have a high diagnostic yield in a southern European population with cblC defect. Although the identification of the gene defect per se does not predict completely time and severity of disease appearance, our data corroborate the importance of a molecular testing to offer accurate prenatal diagnosis to couples at high risk of having affected children.

Resting energy expenditure in disorders of propionate metabolism

OBJECTIVES

During intercurrent illness children with methylmalonic acidemia were found to have increased resting energy expenditure (REE). We measured REE in children with disorders of propionate metabolism (methylmalonic and propionic acidemia) when they were well and compared the values with those predicted by the Schofield equation.

STUDY DESIGN

Prospective study in tertiary care facility. REE was measured with open-circuit indirect calorimetry under standardized conditions. Predicted REE values were calculated with the Schofield equation. Fourteen subjects with propionic acidemia (n = 3) and methylmalonic acidemia (n = 11) were studied.

RESULTS

The median REE was 690 kcal/d (range 186 to 1687 kcal/d), which is significantly reduced, representing 80% +/- 18% of that predicted by the Schofield height and weight equation (P <.01). REE was significantly lower in female compared with male patients for unknown reasons. There were no differences with age or neurologic state. REE was not further reduced in those with chronic renal failure.

CONCLUSION

REE in patients with disorders of propionate metabolism is reduced when they are well.

Low-affinity kainate receptors and long-lasting depression of NMDA-receptor-mediated currents in rat superficial dorsal horn

In an in vitro spinal cord slice preparation whole cell electrophysiological recordings of rat superficial dorsal horn neurons responding differentially to glutamate (Glu) and N-methyl-D-aspartate (NMDA) were investigated systematically for the role of kainate (KA) receptors in modulating their activity. In these neurons, coapplication of Glu and NMDA, as well as application of Glu immediately before NMDA, induced long- and short-lasting depressions of NMDA-induced currents as well as depression of NMDA-receptor-mediated excitatory postsynaptic currents. KA applied before NMDA mimicked Glu-induced attenuating effects. Furthermore, the low-affinity KA receptor antagonist 5-nitro-6,7,8,9- tetrahydrobenzo[G]indole-2,3-dione-3-oxime potentiated Glu-induced NMDA-receptor-mediated currents in neurons responding differentially to Glu and NMDA. These results provide evidence for a novel mechanism, which may relate to classical long-term depression, involving low-affinity KA receptors in long-lasting modulation of NMDA-receptor-mediated currents. This implies a physiological role of KA receptors in long-term modulation of sensory transmission in the superficial dorsal horn of rat spinal cord.

[A case of Legionella pneumophila pneumonia]

Legionella pneumophila is an uncommon cause of pneumonia, mainly in children. We present a case with aggressive disease and unfavourable outcome. The diagnosis was established by serum antibody detection and immunofluorescence and culture of a fragment of lung tissue obtained at necropsy. We focus the importance of this aetiology in nosocomial pneumonia and community-acquired pneumonia with an atypical evolution. The need for specific therapy and some preventive measures are also stressed.

Prevalence of psychological impairment in city and country samples

A study was conducted of the psychological health of 125 married French women aged between 35 and 39 years, divided into five professional groups of 25 subjects. Two of these groups were taken from a rural area, three from Paris. The criteria of health have been psychiatric symptomatology, psychological impairment, and the frequency of the periods of impairment. A significant difference was found between the farmers and all the other groups. Differential data are also given regarding the medical assistance received by the groups.