Raphael Schiffmann M.D.

Abdelwahab, M., D. Blankenship and R. Schiffmann (2016). “Long-term follow-up and sudden unexpected death in gaucher disease type 3 in egypt.” Neurol Genet 2(2): e55.

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OBJECTIVE: To describe the long-term follow-up and distinct phenotype of a large cohort of patients with Gaucher disease type 3 on enzyme replacement therapy (ERT) in Egypt. METHODS: A prospective cohort study of 78 patients on ERT who were followed for up to 9 years with yearly evaluations that included EEG and cognitive testing. RESULTS: Of the patients, 73% were homozygous for the L444P GBA1 mutation; all but 7 were neurologically symptomatic. Supranuclear gaze palsy with variable but stable cognitive function was present in 91% of patients. Convergent strabismus and bulbar dysfunction were noted in 22% and 37%, respectively. Features of oppositional defiant disorder were present in 54% of patients. Twenty-three patients (30%) developed seizures while on ERT for 1-9 years. Of those, 12 patients (15%) died suddenly and unexpectedly at a mean age of 6.7 +/- 5.0 years (range 1.5-18). Sudden death was usually associated with a seizure disorder or a terminal seizure, but 7 of 12 patients had a preceding normal EEG. An additional 11% had background slowing or epileptogenic activity on EEG without clinical seizures. There were 3 familial cases of sudden unexpected death. CONCLUSIONS: Despite having the most common GBA1 genotype known to be associated with neuronopathic Gaucher disease, patients with Gaucher disease type 3 in Egypt have a phenotype and a clinical outcome on ERT that are very different from those observed in other populations. Identifying putative modifying genes of this ethnic group is likely to lead to better therapy for neuronopathic Gaucher disease generally.

Mochel, F., E. Hainque, D. Gras, I. M. Adanyeguh, S. Caillet, B. Heron, A. Roubertie, E. Kaphan, R. Valabregue, D. Rinaldi, S. Vuillaumier, R. Schiffmann, C. Ottolenghi, J. Y. Hogrel, L. Servais and E. Roze (2016). “Triheptanoin dramatically reduces paroxysmal motor disorder in patients with glut1 deficiency.” J Neurol Neurosurg Psychiatry 87(5): 550-553.

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OBJECTIVE: On the basis of our previous work with triheptanoin, which provides key substrates to the Krebs cycle in the brain, we wished to assess its therapeutic effect in patients with glucose transporter type 1 deficiency syndrome (GLUT1-DS) who objected to or did not tolerate ketogenic diets. METHODS: We performed an open-label pilot study with three phases of 2 months each (baseline, treatment and withdrawal) in eight patients with GLUT1-DS (7-47 years old) with non-epileptic paroxysmal manifestations. We used a comprehensive patient diary to record motor and non-motor paroxysmal events. Functional (31)P-NMR spectroscopy was performed to quantify phosphocreatine (PCr) and inorganic phosphate (Pi) within the occipital cortex during (activation) and after (recovery) a visual stimulus. RESULTS: Patients with GLUT1-DS experienced a mean of 30.8 (+/-27.7) paroxysmal manifestations (52% motor events) at baseline that dropped to 2.8 (+/-2.9, 76% motor events) during the treatment phase (p=0.028). After withdrawal, paroxysmal manifestations recurred with a mean of 24.2 (+/-21.9, 52% motor events; p=0.043). Furthermore, brain energy metabolism normalised with triheptanoin, that is, increased Pi/PCr ratio during brain activation compared to the recovery phase (p=0.021), and deteriorated when triheptanoin was withdrawn. CONCLUSIONS: Treatment with triheptanoin resulted in a 90% clinical improvement in non-epileptic paroxysmal manifestations and a normalised brain bioenergetics profile in patients with GLUT1-DS.

Meng, X. L., T. S. Day, N. McNeill, P. Ashcraft, T. Frischmuth, S. H. Cheng, Z. P. Liu, J. S. Shen and R. Schiffmann (2016). “Molecular basis for globotriaosylceramide regulation and enzyme uptake in immortalized aortic endothelial cells from Fabry mice.” J Inherit Metab Dis. Mar 10. [Epub ahead of print]

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Fabry disease is caused by deficient activity of alpha-galactosidase A and subsequent intracellular accumulation of glycosphingolipids, mainly globotriaosylceramide (Gb3). Vascular endothelial cells may play important roles in disease pathogenesis, and are one of the main target cell types in therapeutic interventions. In this study, we generated immortalized aortic endothelial cell lines from a mouse model of Fabry disease. These cells retained endothelial cell-specific markers and functions. Gb3 expression level in one of these clones (referred to as FMEC2) was highly susceptible to culture media, and appeared to be regulated by glucosylceramide synthase. Results also showed that Gb3 could be upregulated by hydrocortisone. FMEC2 express the mannose 6-phosphate receptor and sortilin but not the mannose receptor. Uptake studies suggested that sortilin plays a role in the binding and internalization of mammalian cell-produced alpha-galactosidase A. Moss-aGal (a plant-made enzyme) was endocytosed by FMEC2 via a receptor other than the aforementioned receptors. In conclusion, this study suggests that glucosylceramide synthase and hydrocortisone may play important roles in modulating Gb3 levels in Fabry mouse aortic endothelial cells, and that endocytosis of recombinant alpha-galactosidase A involves a combination of multiple receptors depending on the properties of the enzyme.

Shen, J. S., A. Busch, T. S. Day, X. L. Meng, C. I. Yu, P. Dabrowska-Schlepp, B. Fode, H. Niederkruger, S. Forni, S. Chen, R. Schiffmann, T. Frischmuth and A. Schaaf (2016). “Mannose receptor-mediated delivery of moss-made alpha-galactosidase A efficiently corrects enzyme deficiency in Fabry mice.” J Inherit Metab Dis 39(2): 293-303.

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Enzyme replacement therapy (ERT) is an effective treatment for several lysosomal storage disorders (LSDs). Intravenously infused enzymes are taken up by tissues through either the mannose 6-phosphate receptor (M6PR) or the mannose receptor (MR). It is generally believed that M6PR-mediated endocytosis is a key mechanism for ERT in treating LSDs that affect the non-macrophage cells of visceral organs. However, the therapeutic efficacy of MR-mediated delivery of mannose-terminated enzymes in these diseases has not been fully evaluated. We tested the effectiveness of a non-phosphorylated alpha-galactosidase A produced from moss (referred to as moss-aGal) in vitro and in a mouse model of Fabry disease. Endocytosis of moss-aGal was MR-dependent. Compared to agalsidase alfa, a phosphorylated form of alpha-galactosidase A, moss-aGal was more preferentially targeted to the kidney. Cellular localization of moss-aGal and agalsidase alfa in the heart and kidney was essentially identical. A single injection of moss-aGal led to clearance of accumulated substrate in the heart and kidney to an extent comparable to that achieved by agalsidase alfa. This study suggested that mannose-terminated enzymes may be sufficiently effective for some LSDs in which non-macrophage cells are affected, and that M6P residues may not always be a prerequisite for ERT as previously considered.

Schiffmann, R. (2015). “A genetic form of achlorhydria and gastritis.” American Journal of Clinical Nutrition 102(6): 1615-1615.

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The recent review article on the connection between achlorhydria and iron deficiency anemia concludes that gastritis-induced achlorhydria can be an independent cause of iron deficiency anemia. I would like to attract your attention to a little-known autosomal recessive genetic disease, mucolipidosis type IV (MLIV), in which all patients have constitutive achlorhydria. MLIV is caused by mutation of the MCOLN1 gene that encodes the endosomal/lysosomal transient receptor potential channel protein mucolipin 1 (TRPML1). The exact mechanism by which this nonselective cation channel deficiency prevents hydrochloric acid secretion is incompletely understood. Parietal cells in MLIV are present in seemingly normal numbers, are full of large vacuoles, yet produce normal amounts of intrinsic factor. All patients tested thus far were achlorhydric with up to 10-fold elevations in blood gastrin, which is useful for disease screening (5). Mucosal atrophy was present in biopsy samples, with increasing chronic inflammation with age. Fifty percent of patients with MLIV have iron deficiency anemia, which can be corrected with oral iron preparations. Because the achlorhydria is congenital, it is likely that it leads over time to both gastritis and iron deficiency but that the presence of gastritis is not necessary for abnormal absorption of food iron. To our knowledge, MLIV is the only single-gene disorder associated with a selective defect of gastric hydrochloric acid secretion.