[Current and new therapeutic options in inborn errors of metabolism]. / Actualités thérapeutiques dans les erreurs innées du métabolisme.

Inborn errors of metabolism (IEM) represent a vast group of orphan genetic disorders associated with enzyme deficiencies, substrates accumulation and products depletion. For several decades, the cornerstone of life-saving therapies in IEM was based on extreme manipulations of the nutritional intakes. Such outstanding dietary engineering is still relevant today, but new therapeutic avenues have emerged last years, based on better pathophysiological understanding and technological advances. In this paper, we summarize current and new therapeutic options in the field of IEM.

Les erreurs innées du métabolisme (EIM) représentent un groupe de conditions génétiques associées à une déficience enzymatique causant une accumulation du substrat en amont de la réaction et une déficience du produit en aval. Pendant des décennies, la pierre angulaire du traitement de ces affections a été basée sur des régimes drastiquement restrictifs. Ces manipulations diététiques extrêmes sont encore aujourd'hui d'actualité, mais l'arsenal thérapeutique s'est considérablement élargi ces dernières années, basé sur de meilleures connaissances physiopathologiques et sur des progrès technologiques et pharmacologiques. Dans cet article, nous résumons les différentes stratégies et nouveautés thérapeutiques dans le domaine des erreurs innées du métabolisme.

[Association between exposure to persistent organic pollutants during pregnancy and thyroid function during childhood : a pilot longitudinal study and literature review]. / Associations entre exposition aux polluants organiques persistants durant la grossesse et fonction thyroïdienne durant la petite enfance : étude longitudinale pilote et revue de la littérature.

OBJECTIVE: Perfluoroalkyl substances (PFAS) are chemicals widely employed in the industry. Long term consequences of the newborns' contamination by PFAS on thyroid function are of concern. The aim of this study is to assess the potential associations between PFAS contamination measured at birth and thyroid function assessed few months later. PFAS levels were previously determined in cord blood from a cohort of newborns recruited in Liege. METHOD: Parents of the children belonging to the first and the fifth quintiles of exposure to PFAS were contacted in order to measure the thyroid stimulating hormone (TSH) levels in their child few months after birth. Twenty-eight children participated in the study. Moreover, we performed a literature review about associations between pre- or perinatal exposure to persistent organic pollutants and thyroid function during early childhood. RESULT: No significant difference was highlighted between both groups of contamination (Mann-Whitney, p-value = 0.91). Literature review highlighted the critical need of new longitudinal data about this problematic. CONCLUSION: Our results suggest that the PFAS levels at birth are not associated with TSH levels later in life. Large scale studies are required to confirm our results.

Objectif : Notre but est d'étudier les associations potentielles entre contamination par les composés perfluorés (PFC) mesurée à la naissance et fonction thyroïdienne évaluée quelques mois plus tard. Les niveaux de PFC ont été déterminés précédemment dans le sang de cordon de nouveau-nés recrutés à Liège. Méthode : Les parents des enfants appartenant au premier et cinquième quintiles d'exposition aux PFC ont été contactés pour mesurer les niveaux de thyréostimuline (TSH) chez leurs enfants quelques mois après la naissance. Vingt-huit enfants ont été recrutés. De plus, nous avons réalisé une revue de littérature concernant les associations entre exposition pré- ou périnatale aux polluants organiques persistants (POP) et fonction thyroïdienne pendant la petite enfance. Résultat : Aucune différence significative n'a été mise en évidence entre les deux groupes de contamination (Mann-Whitney, p = 0,91). Selon, la revue de la littérature, il est indispensable de disposer de nouvelles données longitudinales relatives à la relation entre contamination par les POP et fonction thyroïdienne. Conclusion : Nos résultats suggèrent que les concentrations de PFC à la naissance ne sont pas associées aux niveaux de TSH au cours de la vie. Des études basées sur de plus grandes cohortes sont requises pour confirmer nos résultats.

[(S)un (M)ay (A)rise on SMA : the hope of a region without spinal muscular atrophy]. / (S)un (M)ay (A)rise on SMA : l'espoir d'une région sans amyotrophie spinale.

The treatment of spinal muscular atrophy (SMA) has considerably changed over the last 3 years. Several approaches that aim to increase the deficient SMN protein have demonstrated an efficacy that is inversely correlated with disease duration. In this context, newborn screening (NBS) is increasingly considered as the next step in several countries or regions. In 2018, we initiated a pilot study for NBS of SMA in French- and German-speaking Belgium. We aim to evaluate the feasibility, the efficacy, and the cost-effectiveness of such a program. Initially covering the region of Liege, the program was recently extended to the whole Southern Belgium and currently covers about 55.000 newborns per year. On June 1st 2019, 35.000 newborns had been screened and 5 affected babies were identified and referred to neuromuscular centers for early treatment. A full evaluation of the program will take place after three years to consider the inclusion of SMA screening in the publically-funded NBS program in Southern Belgium.

La prise en charge de l'amyotrophie spinale antérieure (SMA) a considérablement évolué au cours des trois dernières années. Les différents essais visant à augmenter la production de la protéine SMN déficitaire dans la SMA ont systématiquement montré une efficacité inversement proportionnelle à la durée de la maladie. Dès lors, l'implémentation d'un programme de dépistage néonatal s'est rapidement imposée comme une évidence médico-économique dans de nombreux pays. Dans ce contexte, nous avons initié un programme de dépistage néonatal pour la SMA en Belgique francophone et germanophone. En 2018, une étude pilote de trois ans visant à évaluer la faisabilité, l'efficacité et la rentabilité du screening a été initiée au sein du centre de dépistage de Liège. L'étude a récemment été étendue à l'ensemble de la Fédération Wallonie-Bruxelles (FWB) pour couvrir environ 55.000 naissances annuelles. Au 1er juin 2019, 35.000 bébés ont été dépistés et cinq nouveau-nés atteints de SMA ont été identifiés. Tous ont été immédiatement référés pour assurer leur prise en charge dans un centre de référence pour les maladies neuromusculaires. Une évaluation complète du programme aura lieu à l'issue de la phase pilote, afin d'envisager que la SMA soit reconnue comme maladie officielle du programme de dépistage néonatal en FWB.

[Neonatal screening for cystic fibrosis : towards a national implementation in Belgium in 2019]. / Dépistage néonatal de la mucoviscidose : vers une implémentation nationale en Belgique en 2019.

Cystic fibrosis has in Belgium a prevalence of 1/2.850 births, with a median age at diagnosis of 7 months according to the latest data from the Belgian registry of 2015. In our country, the diagnosis of cystic fibrosis is always based on signs and symptoms of the disease. However, because the scientific literature has largely demonstrated the benefits of neonatal screening for cystic fibrosis, it will be implemented in Belgium before the end of 2019. The screening programme should be framed by strict quality criteria in order to obtain the best performance with the least possible inconvenience.

La mucoviscidose a une prévalence en Belgique de 1/2.850 naissances, avec un âge médian au diagnostic de 7 mois selon les dernières données du registre belge de 2015. Dans notre pays, le diagnostic de mucoviscidose est majoritairement basé sur les signes et les symptômes de la maladie. Toutefois, la littérature scientifique ayant largement démontré les avantages d'un dépistage néonatal de la mucoviscidose, celui-ci sera implémenté en Belgique avant la fin 2019. Il convient que le programme de dépistage soit encadré de critères de qualité stricts afin d'obtenir la meilleure performance, avec le moins d'inconvénients possibles.

Innovative PCR without DNA extraction for African sickle cell disease diagnosis.

OBJECTIVES: Hemoglobin (Hb) disorders consist of thalassemia and Hb structural variants, of which the major forms are associated with severe anemia and/or vascular occlusion. Current diagnostic techniques are highly accurate and mostly based on isoelectric focusing, high-performance liquid chromatography or mass spectrometry, which often require advanced laboratory equipment. In sub-Saharan Africa, the Hb disorders are mainly associated to the pathological variants hemoglobin S (HbS) and HbC. Unfortunately, until now, it is not easy to get a diagnosis of these disorders in this area. In this study, we tested the performance of a new molecular diagnostic tests on qualified samples. METHODS: The Human Hb S/C Lamp assay is a new polymerase chain reaction test able to detect HbS, HbC and HbA alleles without DNA extraction, directly on fresh or frozen blood samples, or on dried blood spots (DBS). In this study, we compared the genotyping of 248 blood samples (56 whole blood and 192 DBS) with this LAMP assay to the routine diagnostic methods performed in the genetics lab at the university hospital of Liège. RESULTS: Our results show that the LAMP method can detect HbS and HbC with an accuracy of 100%. Moreover, this test can be used for the neonatal screening because we did not observe any interference with fetal Hb. DISCUSSION: To our knowledge, this method is the only molecular assay that can be performed directly on dried blood cards without DNA extraction, lowering handling, turnaround time and costs.

A next-generation newborn screening pilot study: NGS on dried blood spots detects causal mutations in patients with inherited metabolic diseases.

The range of applications performed on dried blood spots (DBS) widely broadened during the past decades to now include next-generation sequencing (NGS). Previous publications provided a general overview of NGS capacities on DBS-extracted DNA but did not focus on the identification of specific disorders. We thus aimed to demonstrate that NGS was reliable for detecting pathogenic mutations on genomic material extracted from DBS. Assuming the future implementation of NGS technologies into newborn screening (NBS), we conducted a pilot study on fifteen patients with inherited metabolic disorders. Blood was collected from DBS. Whole-exome sequencing was performed, and sequences were analyzed with a specific focus on genes related to NBS. Results were compared to the known pathogenic mutations previously identified by Sanger sequencing. Causal mutations were readily characterized, and multiple polymorphisms have been identified. According to variant database prediction, an unexplained homozygote pathogenic mutation, unrelated to patient's disorder, was also found in one sample. While amount and quality of DBS-extracted DNA are adequate to identify causal mutations by NGS, bioinformatics analysis revealed critical drawbacks: coverage fluctuations between regions, difficulties in identifying insertions/deletions, and inconsistent reliability of database-referenced variants. Nevertheless, results of this study lead us to consider future perspectives regarding "next-generation" NBS.

[Hypophosphatasia]. / L'hypophosphatasie.

Hypophosphatasia (HPP) is a rare genetic disorder characterized by the diminution of the enzymatic activity of the alkaline phosphatase (ALP). The disease mainly involves multiple defects of the mineralization of the skeleton including bone fragilities. It will be expressed to varying degrees of severity and will allow to characterize different forms of HPP. Unfortunately, the prevalence of this pathology remains probably underestimated and its diagnosis must be multidisciplinary by taking into account the biochemical assays, the clinical history as well as the radiological imaging. So, in the approach of this diagnosis, a retrospective screening was carried out by the clinical chemistry department of the CHU of Liège. The aim of this study is to potentially identify the affected patients on the basis of their biochemical assays and their anamnesis in order to propose a genetic screening. Unfortunately, no case could be formally identified, which testifies the difficulty to establish a diagnosis of the slight forms encountered mainly in the adults.

L'hypophosphatasie (HPP) est une pathologie héréditaire rare caractérisée par une diminution de l'activité enzymatique de la phosphatase alcaline (PAL). La maladie entraîne, principalement, de multiples défauts de minéralisation du squelette conduisant à des fragilités osseuses, qui s'exprimeront à des degrés plus ou moins sévères et permettront de caractériser différentes formes d'HPP. Malheureusement, la prévalence de cette pathologie reste probablement sous-estimée et son diagnostic doit être pluridisciplinaire, en prenant en compte les dosages biochimiques, l'histoire clinique du patient ainsi que des iconographies radiologiques. C'est donc dans une optique de diagnostic que nous avons réalisé un screening rétrospectif au sein du laboratoire de chimie clinique du CHU de Liège. Le but de cette étude était d'identifier des patients potentiellement atteints par cette pathologie sur base de leurs dosages biochimiques et d'une clinique évocatrice afin de proposer un dépistage génétique. Malheureusement, aucun cas n'a pu être formellement identifié, ce qui témoigne de la difficulté d'établir un diagnostic des formes légères rencontrées et ce, principalement chez l'adulte.

Samaras and seedlings of Acer pseudoplatanus are potential sources of hypoglycin A intoxication in atypical myopathy without necessarily inducing clinical signs.

REASONS FOR PERFORMING STUDY: Ingestion of sycamore seeds (Acer pseudoplatanus) is the likely source of hypoglycin A in atypical myopathy (AM) but ingestion of seedlings in spring might also contribute to intoxication. OBJECTIVES: To test for hypoglycin A in seeds and seedlings collected on pastures where AM cases were reported and compare its concentration in serum of affected and healthy horses. STUDY DESIGN: Field investigation of clinical cases. METHODS: Whenever present, samaras (the winged nuts that each contain one seed) and/or seedlings were collected from pastures of 8 AM cases and 5 unaffected horses from different premises. Two AM cases were each co-grazing with an apparently healthy horse. Acylcarnitines and hypoglycin A were quantified in blood samples of all horses involved in the study. RESULTS: Hypoglycin A was detected in serum of AM (5.47 ± 1.60 µmol/l) but not in healthy controls pasturing where A. pseudoplatanus trees were not present. However, hypoglycin A was detected at high concentrations (7.98 µmol/l) in serum of a clinically healthy horse grazing a pasture with seedlings and samaras and also in the 2 healthy horses co-grazing with AM cases (0.43 ± 0.59 µmol/l). Hypoglycin A was detected in all samples of seeds and spring seedlings of A. pseudoplatanus. CONCLUSIONS: Atypical myopathy can be associated with the ingestion of sycamore samaras and also ingestion of seedlings. Hypoglycin A can be detected in the blood of horses with no detectable clinical signs at pasture in which there is A. pseudoplatanus. Determination of hypoglycin A concentration in blood is useful for screening for exposure in suspected cases of AM.

Diagnostic pitfall in antenatal manifestations of CPT II deficiency.

Carnitine palmitoyltransferase II (CPT2) deficiency is a rare inborn error of mitochondrial fatty acid metabolism associated with various phenotypes. Whereas most patients present with postnatal signs of energetic failure affecting muscle and liver, a small subset of patients presents antenatal malformations including brain dysgenesis and neuronal migration defects. Here, we report recurrence of severe cerebral dysgenesis with Dandy-Walker malformation in three successive pregnancies and review previously reported antenatal cases. Interestingly, we also report that acylcarnitines profile, tested retrospectively on the amniotic fluid of last pregnancy, was not sensitive enough to allow reliable prenatal diagnosis of CPT2 deficiency. Finally, because fetuses affected by severe cerebral malformations are frequently aborted, CPT2 deficiency may be underestimated and fatty acid oxidation disorders should be considered when faced with a fetus with Dandy-Walker anomaly or another brain dysgenesis.

Detection of hypoglycin A in the seeds of sycamore (Acer pseudoplatanus) and box elder (A. negundo) in New Zealand; the toxin associated with cases of equine atypical myopathy.

CASE HISTORY AND CLINICAL FINDINGS: During April and May 2014 four horses aged between 5 months and 9 years, located in the Canterbury, Marlborough and Southland regions, presented with a variety of clinical signs including recumbency, stiffness, lethargy, dehydration, depression, and myoglobinuria suggestive of acute muscle damage. Two horses were subjected to euthanasia and two recovered. In all cases seeds of sycamore maple (Acer pseudoplatanus) or box elder (A. negundo) were present in the area where the horse had been grazing. LABORATORY INVESTIGATION: The samaras (seeds) of some Acer spp. may contain hypoglycin A, that has been associated with cases of atypical myopathy in Europe and North America. To determine if hypoglycin A is present in the samaras of Acer spp. in New Zealand, samples were collected from trees throughout the country that were associated with historical and/or current cases of atypical myopathy, and analysed for hypoglycin A. Serum samples from the four cases and four unaffected horses were analysed for the presence of hypoglycin A, profiles of acylcarnitines (the definitive diagnosis for atypical myopathy) and activities of creatine kinase and aspartate aminotransferase.Markedly elevated serum activities of creatine kinase and aspartate aminotransferase, and increased concentrations of selected acylcarnitines were found in the case horses. Hypoglycin A was detected in the serum of those horses but not in the healthy controls. Hypoglycin A was detected in 10/15 samples of samaras from sycamore maple and box elder from throughout New Zealand. DIAGNOSIS: Cases of atypical myopathy were diagnosed on properties where samaras containing hypoglycin A were also found. CLINICAL RELEVANCE: Sycamore and box elder trees in New Zealand are a source of hypoglycin A associated with the development of atypical myopathy. If pastured horses present with clinical and biochemical signs of severe muscle damage then the environment should be checked for the presence of these trees. Horses should be prevented from grazing samaras from Acer spp. in the autumn.

Folinic acid treatment for schizophrenia associated with folate receptor autoantibodies.

BACKGROUND: Auto-antibodies against folate receptor alpha (FRα) at the choroid plexus that block N(5)-methyltetrahydrofolate (MTHF) transfer to the brain were identified in catatonic schizophrenia. Acoustic hallucinations disappeared following folinic acid treatment. Folate transport to the CNS prevents homocysteine accumulation and delivers one-carbon units for methyl-transfer reactions and synthesis of purines. The guanosine derivative tetrahydrobiopterin acts as common co-factor for the enzymes producing dopamine, serotonin and nitric oxide. METHODS: Our study selected patients with schizophrenia unresponsive to conventional treatment. Serum from these patients with normal plasma homocysteine, folate and vitamin B12 was tested for FR autoantibodies of the blocking type on serial samples each week. Spinal fluid was analyzed for MTHF and the metabolites of pterins, dopamine and serotonin. The clinical response to folinic acid treatment was evaluated. RESULTS: Fifteen of 18 patients (83.3%) had positive serum FR auto-antibodies compared to only 1 in 30 controls (3.3%) (χ(2)=21.6; p<0.0001). FRα antibody titers in patients fluctuated over time varying between negative and high titers, modulating folate flux to the CNS, which explained low CSF folate values in 6 and normal values in 7 patients. The mean±SD for CSF MTHF was diminished compared to previously established controls (t-test: 3.90; p=0.0002). A positive linear correlation existed between CSF MTHF and biopterin levels. CSF dopamine and serotonin metabolites were low or in the lower normal range. Administration of folinic acid (0.3-1mg/kg/day) to 7 participating patients during at least six months resulted in clinical improvement. CONCLUSION: Assessment of FR auto-antibodies in serum is recommended for schizophrenic patients. Clinical negative or positive symptoms are speculated to be influenced by the level and evolution of FRα antibody titers which determine folate flux to the brain with up- or down-regulation of brain folate intermediates linked to metabolic processes affecting homocysteine levels, synthesis of tetrahydrobiopterin and neurotransmitters. Folinic acid intervention appears to stabilize the disease process.

Identification of methylenecyclopropyl acetic acid in serum of European horses with atypical myopathy.

REASONS FOR PERFORMING STUDY: It is hypothesised that European atypical myopathy (AM) has a similar basis as seasonal pasture myopathy in North America, which is now known to be caused by ingestion of hypoglycin A contained in seeds from the tree Acer negundo. Serum from horses with seasonal pasture myopathy contained the conjugated toxic metabolite of hypoglycin A, methylenecyclopropyl acetic acid (MCPA). STUDY DESIGN: Retrospective study on archived samples. OBJECTIVES: 1) To determine whether MCPA-carnitine was present in serum of European horses confirmed to have AM; 2) to determine whether Acer negundo or related Acer species were present on AM pastures in Europe. METHODS: Concentrations of MCPA-carnitine were analysed in banked serum samples of 17 AM horses from Europe and 3 diseased controls (tetanus, neoplasia and exertional rhabdomyolysis) using tandem mass spectrometry. Atypical myopathy was diagnosed by characteristic serum acylcarnitine profiles. Pastures of 12 AM farms were visited by experienced botanists and plant species were documented. RESULTS: Methylenecyclopropyl acetic acid-carnitine at high concentrations (20.39 ± 17.24 nmol/l; range 0.95-57.63 nmol/l; reference: <0.01 nmol/l) was identified in serum of AM but not disease controls (0.00 ± 0.00 nmol/l). Acer pseudoplatanus but not Acer negundo was present on all AM farms. CONCLUSIONS: Atypical myopathy in Europe, like seasonal pasture myopathy in North America, is highly associated with the toxic metabolite of hypoglycin A, MCPA-carnitine. This finding coupled with the presence of a tree of which seeds are known to also contain hypoglycin A indicates that ingestion of Acer pseudoplatanus is the probable cause of AM. This finding has major implications for the prevention of AM.

Hepatocyte transplantation using the domino concept in a child with tetrabiopterin nonresponsive phenylketonuria.

Phenylketonuria is a metabolic disease caused by phenylalanine hydroxylase deficiency. Treatment is based on a strict natural protein-restricted diet that is associated with the risk of malnutrition and severe psychosocial burden. Oral administration of tetrahydrobiopterin can increase residual enzyme activity, but most patients with severe clinical phenotypes are nonresponders. We performed liver cell transplantation in a 6-year-old boy with severe tetrahydrobiopterin nonresponsive phenylketonuria who failed to comply with diet prescriptions. The transplanted hepatocytes were obtained in part from an explanted glycogen storage type 1b liver. Following two infusions, blood phenylalanine levels returned within the therapeutic target while the phenylalanine half-life assessed by loading tests decreased from 43 to 19 h. However, 3 months later, blood phenylalanine concentrations increased and the phenylalanine intake had to be reduced. Cell-based therapy is a promising therapeutic option in phenylketonuria, and the domino concept may solve the issue of cell sources for hepatocyte transplantation.

Acute hepatitis with prolonged cholestasis and disappearance of interlobular bile ducts following tibolone and Hypericum perforatum (St. John's wort). Case of drug interaction?

The case of a patient under tibolone therapy for two years who developed a mixed-type liver injury with prolonged cholestasis and features of the vanishing bile duct syndrome following a ten weeks treatment with St. John wort (Hypericum Perforatum) infusions is reported. In the absence of evidence of a potential role for concomitant medication i.e. hydroxychloroquine sulfate to play a role in the clinical, biochemical and morphological picture, an interaction between the herbal preparation and tibolone was suspected as the likely cause of liver damage.

Conservative treatment of postsurgical lymphatic leaks with somatostatin-14.

Successful management of lymphatic leaks by continuous IV administration of somatostatin was first reported by Ulibarri and coworkers in Spain,(1) and more recently by authors from Italy(2) and Switzerland.(3) The present article reports the clinical history of two patients in whom postsurgical lymphatic leak was successfully treated after the administration of either somatostatin-14 alone (case 1) or combined somatostatin-14 and total parenteral nutrition (TPN; case 2). Although further pathophysiologic studies are needed for the elucidation of its mechanisms of action, somatostatin-14 seems to be an intriguing therapy against postsurgical lymphatic leaks that may make potentially risky transthoracic reoperation unnecessary.