Ceroid lipofuscinosis type 2 disease: Effective presymptomatic therapy-Oldest case of a presymptomatic enzyme therapy

Neuronal ceroid lipofuscinosis type 2 (CLN2) disease is a rare, lysosomal storage disorder that causes pediatric onset neurodegenerative disease. It is characterized by mutations in the TPP1 gene. Symptoms begin between 2 and 4 years of age with loss of previously acquired motor, cognitive, and language abilities. Cerliponase alfa, a recombinant human TPP1 enzyme, is the only approved therapy. We report the first presymptomatic cerliponase alfa intraventricular treatment in a familial case of CLN2 related to a classical TPP1 variant. Sister 1 presented with motor, cognitive, and language decline and progressive myoclonic epilepsy since the age of 3 years, evolved with severe diffuse encephalopathy, received no specific treatment, and died at 11 years. Sister 2 had a CLN2 presymptomatic diagnosis and has been treated with cerliponase since she was 12 months old. She is now 6 years 8 months and has no CLN2 symptom except one generalized seizure 1 year ago. No serious adverse event has occurred. Repeated Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition standardized index scores are heterogeneous in the extremely low to low average ranges. Mean length of utterances, a global index of sentence complexity, showed a delay, but a gradual improvement. The reported case enhances the major contribution of presymptomatic diagnosis and significant middle-term treatment benefit for patients with CLN2.

Long-term follow-up of 64 children with classical infantile-onset Pompe disease since 2004: A French real-life observational study

BACKGROUND

Classical infantile-onset Pompe disease (IOPD) is the most severe form of Pompe disease. Enzyme replacement therapy (ERT) has significantly increased survival but only a few studies have reported long-term outcomes.

METHODS

We retrospectively analyzed the outcomes of classical IOPD patients diagnosed in France between 2004 and 2020.

RESULTS

Sixty-four patients were identified. At diagnosis (median age 4 months) all patients had cardiomyopathy and most had severe hypotonia (57 of 62 patients, 92%). ERT was initiated in 50 (78%) patients and stopped later due to being ineffective in 10 (21%). Thirty-seven (58%) patients died during follow-up, including all untreated and discontinued ERT patients, and 13 additional patients. Mortality was higher during the first 3 years of life and after the age of 12 years. Persistence of cardiomyopathy during follow-up and/or the presence of heart failure were highly associated with an increased risk of death. In contrast, cross-reactive immunologic material (CRIM)-negative status (n = 16, 26%) was unrelated to increased mortality, presumably because immunomodulation protocols prevent the emergence of high antibody titers to ERT. Besides survival, decreased ERT efficacy appeared after the age of 6 years, with a progressive decline in motor and pulmonary functions for most survivors.

CONCLUSIONS

This study reports the long-term follow-up of one of the largest cohorts of classical IOPD patients and demonstrates high long-term mortality and morbidity rates with a secondary decline in muscular and respiratory functions. This decreased efficacy seems to be multifactorial, highlighting the importance of developing new therapeutic approaches targeting various aspects of pathogenesis.

Natural history of GM1 gangliosidosis-Retrospective cohort study of 61 French patients from 1998 to 2019

GM1 gangliosidosis is a rare lysosomal storage disorder associated with β-galactosidase enzyme deficiency. There are three types of GM1 gangliosidosis based on age of symptom onset, which correlate with disease severity. In 2019, we performed a retrospective multicentric study including all patients diagnosed with GM1 gangliosidosis in France since 1998. We had access to data for 61 of the 88 patients diagnosed between 1998 and 2019. There were 41 patients with type 1 (symptom onset ≤6 months), 11 with type 2a (symptom onset from 7 months to 2 years), 5 with type 2b (symptom onset from 2 to 3 years), and 4 with type 3 (symptom onset >3 years). The estimated incidence in France was 1/210000. In patients with type 1, the first symptoms were hypotonia (26/41, 63%), dyspnea (7/41, 17%), and nystagmus (6/41, 15%), whereas in patients with type 2a, these were psychomotor regression (9/11, 82%) and seizures (3/11, 27%). In types 2b and 3, the initial symptoms were mild, such as speech difficulties, school difficulties, and progressive psychomotor regression. Hypotonia was observed in all patients, except type 3. The mean overall survival was 23 months (95% confidence interval [CI]: 7, 39) for type 1 and 9.1 years (95% CI: 4.5, 13.5) for type 2a. To the best of our knowledge, this is one of the largest historical cohorts reported, which provides important information on the evolution of all types of GM1 gangliosidosis. These data could be used as a historical cohort in studies assessing potential therapies for this rare genetic disease.

Motor outcomes in patients with infantile and juvenile Pompe disease: Lessons from neurophysiological findings

In Infantile Onset Pompe Disease (IOPD), enzyme replacement therapy (ERT) may improve survival, cardiac function, and motor development. However, even with early enzyme replacement therapy, some patients experienced poor response to ERT and abnormal motor milestones that could be due to motor neuron involvement. In this long-term retrospective study, we analyzed concomitant clinical motor outcomes and electroneuromyography (ENMG) findings in patients with IOPD and Juvenile Onset Pompe Disease (JOPD). Twenty-nine pediatric patients were included and 20 surviving were analyzed for neuromotor studies: 12 had IOPD (group 1), 4 had JOPD (group 2) and 4 (group 3) received ERT in the first month of age. Motor nerve conduction studies were mostly normal. Needle EMG performed at diagnosis always indicated the existence of myopathy that responded to ERT. Two IOPD patients (group 1) presenting with mixed motor neuropathy and myopathy displayed a poor outcome and never walked. Two patients became non-walkers (one IOPD patient and one patient of group 3) at respectively 9 and 3 years of age. One JOPD patient is about to lose walking ability. This motor deterioration was associated with the development of a motor neuropathy. Patients older than 10 years of age develop a motor neuropathy. Initial or secondary motor neuron involvement seems to be associated with a poor motor outcome showing that ERT may fail to prevent the accumulation of glycogen in motor neuron. Neurophysiological findings are important to assess severity of motor neuron damage in all Pompe pediatric patients and should be systematically performed.

Plasma GM2 ganglioside potential biomarker for diagnosis, prognosis and disease monitoring of GM2-Gangliosidosis

GM2-Gangliosidosis are a group of inherited lysosomal storage pathologies characterized by a large accumulation of G_M2 ganglioside in the lysosome. They are caused by mutation in HEXA or HEXB causing reduced or absent activity of a lysosomal β-hexosaminidase A, or mutation in GM2A causing defect in GM2 activator protein (GM2AP), an essential protein for the activity of the enzyme. Biochemical diagnosis relies on the measurement of β-hexosaminidases A and B activities, which is able to detect lysosomal enzyme deficiency but fails to identify defects in GM2AP. We developed a rapid, specific and sensitive liquid chromatography-mass spectrometry-based method to measure simultaneously G_M1, G_M2, G_M3 and G_D3 molecular species. Gangliosides were analysed in plasma from 19 patients with GM2-Gangliosidosis: Tay-Sachs (n = 9), Sandhoff (n = 9) and AB variant of GM2-Gangliosidosis (n = 1) and compared to 20 age-matched controls. Among patients, 12 have a late adult-juvenile-onset and 7 have an infantile early-onset of the disease. Plasma G_M2 molecular species were increased in all GM2-Gangliosidosis patients (19/19), including the patient with GM2A mutation, compared to control individuals and compared to patients with different other lysosomal storage diseases. G_M234:1 and G_M234:1/G_M334:1 ratio discriminated patients from controls with 100% sensitivity and specificity. G_M234:1 and G_M234:1/G_M334:1 were higher in patients with early-onset compared to those with late-onset of the disease, suggesting a relationship with severity. Longitudinal analysis in one adult with Tay-Sachs disease over 9 years showed a positive correlation of G_M234:1 and G_M234:1/G_M334:1 ratio with age at sampling. We propose that plasma G_M2 34:1 and its ratio to G_M3 34:1 could be sensitive and specific biochemical diagnostic biomarkers for GM2-Gangliosidosis including AB variant and could be useful as a first line diagnostic test and potential biomarkers for monitoring upcoming therapeutic efficacy.

Neuronal ceroïd-lipofuscinosis: Clinical, electroencephalographic, imaging, and genetic study of a maghrebian series

Our study included 13 patients diagnosed with neuronal ceroidlipofuscinosis. It is a group of rare genetically-determined neurodegenerativediseases characterized by clinical and genetic heterogeneity. brain MRI andelectroencephalogram facilitate diagnosis.

Prenatal-onset of congenital neuronal ceroid lipofuscinosis with a novel CTSD mutation

BACKGROUND

Neuronal ceroid lipofuscinoses (NCLs) form a clinically and genetically heterogeneous group of inherited neurodegenerative disorders that share common neuropathological features. Although they are the first cause of neurodegenerative disorders in children, their congenital forms are rarely documented. They are classically due to mutations in the CTSD gene (the CLN10 disease). Affected newborns usually present severe microcephaly, seizures and respiratory failure leading to death within the first postnatal days or weeks.

CASES

We report on two siblings, in which exome sequencing identified a novel homozygous CTSD variant. The first sib presented at birth with seizures, rapidly progressive postnatal microcephaly and visual deficiency related to retinal dysfunction. Progressive neurological deterioration leads to death at the age of 24 months. Cathepsin D activity was reduced in the cultured fibroblasts of this patient. The second sib, a fetus of 36 weeks of gestation, was delivered after pregnancy termination for brain abnormalities (in accordance with French Legislation) suggesting a recurrence of the disease. Fetal postmortem examination disclosed neuropathological features consistent with NCL.

CONCLUSIONS

Congenital NCL related to CTSD mutations is a neuronal storage disorder that produces in the developing brain diffuse neurodegeneration and white matter atrophy resulting in a progressive and rapidly lethal microcephaly.

Disentangling molecular and clinical stratification patterns in beta-galactosidase deficiency

INTRODUCTION

This study aims to define the phenotypic and molecular spectrum of the two clinical forms of β-galactosidase (β-GAL) deficiency, GM1-gangliosidosis and mucopolysaccharidosis IVB (Morquio disease type B, MPSIVB).

METHODS

Clinical and genetic data of 52 probands, 47 patients with GM1-gangliosidosis and 5 patients with MPSIVB were analysed.

RESULTS

The clinical presentations in patients with GM1-gangliosidosis are consistent with a phenotypic continuum ranging from a severe antenatal form with hydrops fetalis to an adult form with an extrapyramidal syndrome. Molecular studies evidenced 47 variants located throughout the sequence of the GLB1 gene, in all exons except 7, 11 and 12. Eighteen novel variants (15 substitutions and 3 deletions) were identified. Several variants were linked specifically to early-onset GM1-gangliosidosis, late-onset GM1-gangliosidosis or MPSIVB phenotypes. This integrative molecular and clinical stratification suggests a variant-driven patient assignment to a given clinical and severity group.

CONCLUSION

This study reports one of the largest series of b-GAL deficiency with an integrative patient stratification combining molecular and clinical features. This work contributes to expand the community knowledge regarding the molecular and clinical landscapes of b-GAL deficiency for a better patient management.

Design of Si-rich nitride interposer waveguides for efficient light coupling from InP-based QD-emitters to Si3N4 waveguides on a silicon substrate

In this paper, we present a systematic analysis for the design of Si-rich-nitride (SRN) based interposer waveguide layers interfacing InP-based devices and Si₃N₄ waveguides, towards monolithic co-integration of active and passive elements through a Back-End-Of-Line process. The investigation is performed via extensive 2D-eigenvalue and 3D-FDTD electromagnetic simulations and focuses on three different interposer designs, where performance in terms of coupling loss and back reflections is exchanged for fabrication complexity. In addition, a tolerance analysis is performed for the demonstration of the proposed coupling scheme's resilience to fabrication misalignments. The calculations use for the refractive index of the SRN interposer, real values extracted from ellipsometry measurements of a novel ultra-Si-rich-nitride material developed and engineered for this purpose. This new material provides tunability in the real part of the refractive index with low-stress crack free samples grown up to 500nm thickness. Test structures with cutbacks featuring waveguides of 500 × 500nm² cross section formed via e-beam lithography reveal 15dB/cm propagation losses in line with similar amorphous silicon-rich nitride (aSi:N) materials. The proposed coupling concept although assumes an InP active medium, can be applied also with GaAs based lasers and dual facet devices such as Semiconductor Optical Amplifiers (SOAs) and electroabsorption modulators. In addition, all proposed designs are compatible in terms of critical dimensions with low cost 248nm DUV lithography targeting to maximize the low-cost advantage of the Si₃N₄ platform with very high coupling performance. Our results are expected to pave the way for the generation of a versatile, low cost, high performance monolithic InP-Quantum-Dot (QD)/Si₃N₄ platform on a common Si substrate.

Homozygous GRN mutations: new phenotypes and new insights into pathological and molecular mechanisms

Homozygous mutations in the progranulin gene (GRN) are associated with neuronal ceroid lipofuscinosis 11 (CLN11), a rare lysosomal-storage disorder characterized by cerebellar ataxia, seizures, retinitis pigmentosa, and cognitive disorders, usually beginning between 13 and 25 years of age. This is a rare condition, previously reported in only four families. In contrast, heterozygous GRN mutations are a major cause of frontotemporal dementia associated with neuronal cytoplasmic TDP-43 inclusions. We identified homozygous GRN mutations in six new patients. The phenotypic spectrum is much broader than previously reported, with two remarkably distinct presentations, depending on the age of onset. A childhood/juvenile form is characterized by classical CLN11 symptoms at an early age at onset. Unexpectedly, other homozygous patients presented a distinct delayed phenotype of frontotemporal dementia and parkinsonism after 50 years; none had epilepsy or cerebellar ataxia. Another major finding of this study is that all GRN mutations may not have the same impact on progranulin protein synthesis. A hypomorphic effect of some mutations is supported by the presence of residual levels of plasma progranulin and low levels of normal transcript detected in one case with a homozygous splice-site mutation and late onset frontotemporal dementia. This is a new critical finding that must be considered in therapeutic trials based on replacement strategies. The first neuropathological study in a homozygous carrier provides new insights into the pathological mechanisms of the disease. Hallmarks of neuronal ceroid lipofuscinosis were present. The absence of TDP-43 cytoplasmic inclusions markedly differs from observations of heterozygous mutations, suggesting a pathological shift between lysosomal and TDP-43 pathologies depending on the mono or bi-allelic status. An intriguing observation was the loss of normal TDP-43 staining in the nucleus of some neurons, which could be the first stage of the TDP-43 pathological process preceding the formation of typical cytoplasmic inclusions. Finally, this study has important implications for genetic counselling and molecular diagnosis. Semi-dominant inheritance of GRN mutations implies that specific genetic counselling should be delivered to children and parents of CLN11 patients, as they are heterozygous carriers with a high risk of developing dementia. More broadly, this study illustrates the fact that genetic variants can lead to different phenotypes according to their mono- or bi-allelic state, which is a challenge for genetic diagnosis.

A Cross-Sectional Retrospective Study of Non-Splenectomized and Never-Treated Patients with Type 1 Gaucher Disease

Patients with type 1 Gaucher disease (GD1) present thrombocytopenia, anemia, organomegaly, and bone complications. Most experts consider that the less aggressive forms do not require specific treatment. However, little is known about the disease course of these forms. The objective of this cross-sectional retrospective study was to compare the clinical, radiological, and laboratory characteristics of patients with less severe GD1 at diagnosis and at the last evaluation to identify features that might lead to potential complications. Non-splenectomized and never-treated patients (19 women and 17 men) were identified in the French Gaucher Disease Registry (FGDR). Their median age was 36.6 years (2.4–75.1), and their median follow-up was 7.8 years (0.4–32.4). Moreover, 38.7% were heterozygous for the GBA1 N370S variant, and 22.6% for the GBA1 L444P variant. From diagnosis to the last evaluation, GD1 did not worsen in 75% of these patients. Some parameters improved (fatigue and hemoglobin concentration), whereas platelet count and chitotriosidase level remained stable. In one patient (2.7%), Lewy body dementia was diagnosed at 46 years of age. Bone lesion onset was late and usually a single event in most patients. This analysis highlights the genotypic heterogeneity of this subgroup, in which disease could remain stable and even improve spontaneously. It also draws attention to the possible risk of Lewy body disease and late onset of bone complications, even if isolated, to be confirmed in larger series and with longer follow-up.

Intra-monocyte Pharmacokinetics of Imiglucerase Supports a Possible Personalized Management of Gaucher Disease Type 1

BACKGROUND AND OBJECTIVES

Intravenous imiglucerase enzyme replacement therapy for Gaucher disease type 1 administered every 2 weeks is at variance with the imiglucerase plasma half-life of a few minutes. We hypothesized that studying the pharmacokinetics of imiglucerase in blood Gaucher disease type 1 monocytes would be more relevant for understanding enzyme replacement therapy responses.

METHODS

Glucocerebrosidase intra-monocyte activity was studied by flow cytometry. The pharmacokinetics of imiglucerase was analyzed using a population-pharmacokinetic model from a cohort of 31 patients with Gaucher disease type 1 who either started or were receiving long-term treatment with imiglucerase.

RESULTS

A pharmacokinetic analysis of imiglucerase showed a two-compartment model with a high peak followed by a two-phase exponential decay (fast phase half-life: 0.36 days; slow phase half-life: 9.7 days) leading to a median 1.4-fold increase in glucocerebrosidase intra-monocyte activity from the pre-treatment activity (p = 0.04). In patients receiving long-term treatment, for whom the imiglucerase dose per infusion was chosen on the basis of disease aggressiveness/response, imiglucerase clearance correlated with the administered dose. However, the residual glucocerebrosidase intra-monocyte activity value was dose independent, suggesting that the maintenance of imiglucerase residual activity is patient specific. Endogenous pre-treatment glucocerebrosidase intra-monocyte activity was the most informative single parameter for distinguishing patients without (n = 10) and with a clinical indication (n = 17) for starting enzyme replacement therapy (area under the receiver operating characteristic curve: 0.912; 95% confidence interval 0.8-1; p < 0.001), as confirmed also by a factorial analysis of mixed data.

CONCLUSION

This study provides novel pharmacokinetic data that support current imiglucerase administration regimens and suggests the existence of a glucocerebrosidase activity threshold related to Gaucher disease type 1 aggressiveness. These findings can potentially improve Gaucher disease type 1 management algorithms and clinical decision making.

First phenotypic description of a female patient with c.610 T > C variant of GLA: a renal-predominant presentation of Fabry disease

Background

Fabry disease (FD) is an X-linked lysosomal storage disorder due to deficient alpha-galactosidase activity leading to intracellular glycosphingolipid accumulation. Multiple variants have been reported in the GLA gene coding for alpha-galactosidase, and the question of the pathogenicity of rare variants needs to be addressed, especially in patients with mild phenotypes.

Case presentation

The patient, a 37-year-old female, presented with a persistent proteinuria after an otherwise uncomplicated first pregnancy. Renal biopsy showed both mild mesangial IgA deposits, and a striking vacuolization of podocytes and tubular cells consistent with Fabry disease. On electron microscopy, discrete but characteristic pseudo-myelinic lamellar inclusions were observed in the podocytes’ lysosomes. A more detailed physical examination revealed an angiokeratoma, and medical history ancient acroparesthesia. There was no cardiac or cerebral involvement of Fabry disease on magnetic resonance imaging. While blood enzymatic activity of alpha-ga lactosidase was normal in this patient, lysoGb3 was elevated (3 N), and a rare heterozygous variant called c.610 T > C was documented in GLA gene. The patient was treated with an ACE inhibitor, with a rapid decrease in proteinuria. After a 5-year follow-up, her renal function has remained normal, with mild proteinuria, and normal cardiac echography.

Conclusions

We report and phenotypically describe the first case of a Fabry disease female patient carrying the GLA c.610 T > C variant associated with a renal-predominant clinical presentation.

Cornea verticillata and acroparesthesia efficiently discriminate clusters of severity in Fabry disease

BACKGROUD

Fabry disease (OMIM #301 500), the most prevalent lysosomal storage disease, is caused by enzymatic defects in alpha-galactosidase A (GLA gene; Xq22.1). Fabry disease has historically been characterized by progressive renal failure, early stroke and hypertrophic cardiomyopathy, with a diminished life expectancy. A nonclassical phenotype has been described with an almost exclusive cardiac involvement. Specific therapies with enzyme substitution or chaperone molecules are now available depending on the mutation carried. Numerous clinical and fundamental studies have been conducted without stratifying patients by phenotype or severity, despite different prognoses and possible different pathophysiologies. We aimed to identify a simple and clinically relevant way to classify and stratify patients according to their disease severity.

METHODS

Based on data from the French Fabry Biobank and Registry (FFABRY; n = 104; 54 males), we applied unsupervised multivariate statistics to determine clusters of patients and identify clinical criteria that would allow an effective classification of adult patients. Thanks to these criteria and empirical clinical considerations we secondly elaborate a new score that allow the severity stratification of patients.

RESULTS

We observed that the absence of acroparesthesia or cornea verticillata is sufficient to classify males as having the nonclassical phenotype. We did not identify criteria that significantly cluster female patients. The classical phenotype was associated with a higher risk of severe renal (HR = 35.1; p <10-3) and cardiac events (HR = 4.8; p = 0.008) and a trend toward a higher risk of severe neurological events (HR = 7.7; p = 0.08) compared to nonclassical males. Our simple, rapid and clinically-relevant FFABRY score gave concordant results with the validated MSSI.

CONCLUSION

Acroparesthesia and cornea verticillata are simple clinical criteria that efficiently stratify Fabry patients, defining 3 different groups: females and males with nonclassical and classical phenotypes of significantly different severity. The FFABRY score allows severity stratification of Fabry patients.

Paediatric-onset neuronal ceroid lipofuscinosis: first symptoms and presentation at diagnosis

Neuronal ceroid lipofuscinoses (NCLs) are rare, progressive disorders. Through this series of 20 patients with NCL, we illustrate differences between subtypes in their presenting symptoms and clinical, imaging, and electrophysiological results to raise awareness of symptom diversity. Data were available on presenting symptoms, genetics, magnetic resonance imaging (MRI), electroencephalography (including with low-frequency intermittent photic stimulation), visual responses, and electron microscopy. Causal mutations were identified in 10 patients. Eleven patients had neuronal ceroid lipofuscinosis type 2 (CLN2) disease and their most common presenting symptom was seizures, although motor and language defects were also reported. Five patients with CLN2 disease showed abnormalities at initial MRI, but only three showed a photic response with low-frequency stimulation. Seizures were not as common a presenting symptom in other NCL subtypes. Patients with NCLs present with diverse symptoms, which may not be characteristic in early disease stages. These signs and symptoms should lead to rapid diagnostic confirmatory testing for NCLs. WHAT THIS PAPER ADDS: Disease presentation is not uniform for neuronal ceroid lipofuscinoses. Characteristic clinical test results may not be identified in early disease stages.

Natural History of Adult Patients with GM2 Gangliosidosis

OBJECTIVE

GM2 gangliosidoses are lysosomal diseases due to biallelic mutations in the HEXA (Tay-Sachs disease [TS]) or HEXB (Sandhoff disease [SD]) genes, with subsequent low hexosaminidase(s) activity. Most patients have childhood onset, but some experience the first symptoms during adolescence/adulthood. This study aims to clarify the natural history of adult patients with GM2 gangliosidosis.

METHODS

We retrospectively described 12 patients from a French cohort and 45 patients from the literature.

RESULTS

We observed 4 typical presentations: (1) lower motoneuron disorder responsible for proximal lower limb weakness that subsequently expanded to the upper limbs, (2) cerebellar ataxia, (3) psychosis and/or severe mood disorder (only in the TS patients), and (4) a complex phenotype mixing the above 3 manifestations. The psoas was the first and most affected muscle in the lower limbs, whereas the triceps and interosseous were predominantly involved in the upper limbs. A longitudinal study of compound motor action potentials showed a progressive decrease in all nerves, with different kinetics. Sensory potentials were sometimes abnormally low, mainly in the SD patients. The main brain magnetic resonance imaging feature was cerebellar atrophy, even in patients without cerebellar symptoms. The prognosis was mainly related to gait disorder, as we showed that beyond 20 years of disease evolution, half of the patients were wheelchair users.

INTERPRETATION

Improved knowledge of GM2 gangliosidosis in adults will help clinicians achieve correct diagnoses and better inform patients on the evolution and prognosis. It may also contribute to defining proper outcome measures when testing emerging therapies. ANN NEUROL 2020;87:609-617.

Mannose 6-phosphonate labelling: A key for processing the therapeutic enzyme in Pompe disease

In the search of a better enzyme therapy in Pompe disease, the conjugation of mannose 6‐phosphonates to the recombinant enzyme appeared as an enhancer of its efficacy. Here, we demonstrated that the increased efficacy of the conjugated enzyme is partly due to a higher intracellular maturation because of its insensitiveness to acid phosphatases during the routing to lysosomes.

Sleep-disordered breathing in children with mucolipidosis

Mucolipidosis (ML) is a rare lysosomal storage disorder with a wide spectrum of disease severity according to the type. Sleep-disordered breathing is recognized as a characteristic feature of ML but objective data are scarce. The aim of the study was to describe sleep data and medical management in children with ML α/β. All patients with ML α/β followed at a national reference center of ML were included. Five patients had ML II, one patient had ML III and one patient had ML II-III. One patient was started on noninvasive ventilation (NIV) to allow extubation after prolonged invasive mechanical ventilation. The six other patients underwent sleep study at a median age of 1.8 years (range 4 months-17.4 years). Obstructive sleep apnea (OSA) was observed in all patients with a median apnea-hypopnea index (AHI) of 36 events/hr (range 5-52) requiring continuous positive airway pressure (CPAP) or NIV. CPAP/NIV resulted in an improvement of nocturnal gas exchange and was continued in all patients with an excellent compliance. Two patients died. Systematic sleep studies are recommended at time of diagnosis in ML. CPAP or NIV are effective treatments of OSA, well tolerated, and may contribute to improve the quality of life of patients and caregivers.

Intravenous administration of scAAV9-Hexb normalizes lifespan and prevents pathology in Sandhoff disease mice

Sandhoff disease (SD) is a rare inherited disorder caused by a deficiency of β-hexosaminidase activity which is fatal because no effective treatment is available. A mouse model of Hexb deficiency reproduces the key pathognomonic features of SD patients with severe ubiquitous lysosomal dysfunction, GM2 accumulation, neuroinflammation and neurodegeneration, culminating in death at 4 months. Here, we show that a single intravenous neonatal administration of a self-complementary adeno-associated virus 9 vector (scAAV9) expressing the Hexb cDNA in SD mice is safe and sufficient to prevent disease development. Importantly, we demonstrate for the first time that this treatment results in a normal lifespan (over 700 days) and normalizes motor function assessed by a battery of behavioral tests, with scAAV9-treated SD mice being indistinguishable from wild-type littermates. Biochemical analyses in multiple tissues showed a significant increase in hexosaminidase A activity, which reached 10-15% of normal levels. AAV9 treatment was sufficient to prevent GM2 and GA2 storage almost completely in the cerebrum (less so in the cerebellum), as well as thalamic reactive gliosis and thalamocortical neuron loss in treated Hexb-/- mice. In summary, this study demonstrated a widespread protective effect throughout the entire CNS after a single intravenous administration of the scAAV9-Hexb vector to neonatal SD mice.

Late-onset Pompe disease in France: molecular features and epidemiology from a nationwide study

Pompe disease (PD) is caused by a deficiency of lysosomal acid α-glucosidase resulting from mutations in the GAA gene. The clinical spectrum ranges from a rapidly fatal multisystemic disorder (classic PD, onset < 1 year) to a milder adult onset myopathy. The aims of this study were to characterize the GAA mutations, to establish the disease epidemiology, and to identify potential genotype-phenotype correlations in French late-onset PD patients (onset ≥ 2 years) diagnosed since the 1970s. Data were collected from the two main laboratories involved in PD diagnosis and from the French Pompe registry. Two hundred forty-six patients (130 females and 116 males) were included, with a mean age at diagnosis of 43 years. Eighty-three different mutations were identified in the GAA gene, among which 28 were novel. These variants were spread all over the sequence and included 42 missense (one affecting start codon), 8 nonsense, 15 frameshift, 14 splice mutations, 3 small in-frame deletions, and one large deletion. The common c.-32-13T>G mutation was detected in 151/170 index cases. Other frequent mutations included the exon 18 deletion, the c.525del, and the missense mutations c.1927G>A (p.Gly643Arg) and c.655G>A (p.Gly219Arg). Patients carrying the c.-32-13T>G mutation had an older mean age at onset than patients non-exhibiting this mutation (36 versus 25 years). Patients with the same genotype had a highly variable age at onset. We estimated the frequency of late-onset PD in France around 1/69,927 newborns. In conclusion, we characterized the French cohort of late-onset PD patients through a nationwide study covering more than 40 years.

Deep characterization of the anti-drug antibodies developed in Fabry disease patients, a prospective analysis from the French multicenter cohort FFABRY

BACKGROUND

Fabry disease (OMIM #301500) is an X-linked disorder caused by alpha-galactosidase A deficiency with two major clinical phenotypes: classic and non-classic of different prognosis. From 2001, enzyme replacement therapies (ERT) have been available. We aimed to determine the epidemiology and the functional characteristics of anti-drug antibodies. Patients from the French multicenter cohort FFABRY (n = 103 patients, 53 males) were prospectively screened for total anti-agalsidase IgG and IgG subclasses with a home-made enzyme-linked immunosorbent assay (ELISA), enzyme-inhibition assessed with neutralization assays and lysoGb3 plasma levels, and compared for clinical outcomes.

RESULTS

Among the patients exposed to agalsidase, 40% of men (n = 18/45) and 8% of women (n = 2/25) had antibodies with a complete cross-reactivity towards both ERTs. Antibodies developed preferentially in men with non-missense GLA mutations (relative risk 2.88, p = 0.006) and classic phenotype (58.6% (17/29) vs 6.7% (1/16), p = 0.0005). Specific anti-agalsidase IgG1 were the most frequently observed (16/18 men), but the highest concentrations were observed for IgG4 (median 1.89 μg/ml, interquartile range (IQR) [0.41-12.24]). In the men exposed to agalsidase, inhibition was correlated with the total IgG titer (r = 0.67, p < 0.0001), especially IgG4 (r = 0.75, p = 0.0005) and IgG2 (r = 0.72, p = 0.001). Inhibition was confirmed intracellularly in Fabry patient leucocytes cultured with IgG-positive versus negative serum (median: 42.0 vs 75.6%, p = 0.04), which was correlated with IgG2 (r = 0.67, p = 0.017, n = 12) and IgG4 levels (r = 0.59, p = 0.041, n = 12). Plasma LysoGb3 levels were correlated with total IgG (r = 0.66, p = 0.001), IgG2 (r = 0.72, p = 0.004), IgG4 (r = 0.58, p = 0.03) and IgG1 (r = 0.55, p = 0.04) titers. Within the classic group, no clinical difference was observed but lysoGb3 levels were higher in antibody-positive patients (median 33.2 ng/ml [IQR 20.6-55.6] vs 12.5 [10.1-24.0], p = 0.005).

CONCLUSION

Anti-agalsidase antibodies preferentially develop in the severe classic Fabry phenotype. They are frequently associated with enzyme inhibition and higher lysoGb3 levels. As such, they could be considered as a hallmark of severity associated with the classic phenotype. The distinction of the clinical phenotypes should now be mandatory in studies dealing with Fabry disease and its current and future therapies.

Long-term neurologic and cardiac correction by intrathecal gene therapy in Pompe disease

Pompe disease is a lysosomal storage disorder caused by acid-α-glucosidase (GAA) deficiency, leading to glycogen storage. The disease manifests as a fatal cardiomyopathy in infantile form. Enzyme replacement therapy (ERT) has recently prolonged the lifespan of these patients, revealing a new natural history. The neurologic phenotype and the persistence of selective muscular weakness in some patients could be attributed to the central nervous system (CNS) storage uncorrected by ERT. GAA-KO 6neo/6neo mice were treated with a single intrathecal administration of adeno-associated recombinant vector (AAV) mediated gene transfer of human GAA at 1 month and their neurologic, neuromuscular, and cardiac function was assessed for 1 year. We demonstrate a significant functional neurologic correction in treated animals from 4 months onward, a neuromuscular improvement from 9 months onward, and a correction of the hypertrophic cardiomyopathy at 12 months. The regions most affected by the disease i.e. the brainstem, spinal cord, and the left cardiac ventricular wall all show enzymatic, biochemical and histological correction. Muscle glycogen storage is not affected by the treatment, thus suggesting that the restoration of muscle functionality is directly related to the CNS correction. This unprecedented global and long-term CNS and cardiac cure offer new perspectives for the management of patients.

Laboratory diagnosis and follow-up of Romanian Gaucher disease patients

Background: Gaucher disease (GD) is caused by a recessively inherited deficiency of glucocerebrosidase which is encoded by the GBA gene in which nearly 450 mutations have been described. However, only a few genotype- phenotype correlations have been clearly established. The aim of this study was to investigate molecular features of GD in Romanian patients and to evaluate their impact on treatment response. Material and methods: 69 patients, diagnosed between 1997 and 2014 at our national referral laboratory, were included in this study. Frequent point mutations (N370S, L444P, 84GG, R463C) were detected by amplification and restriction enzyme digestion. Recombinant alleles (recTL, recNciI, recA456P) were screened by DNA sequencing. Plasma chitotriosidase served as a biomarker of disease severity throughout the follow-up period. Results: 66 patients had the non-neuronopathic (type 1) form of GD and 3 had the chronic neuronopathic (type 3) phenotype. We identified 79% of the mutant alleles, among which the most frequent mutations were N370S (54%) and L444P (18%). We found a statistically significant (p<0.001) and moderate to good correlation between the total therapeutic dose and the residual chitotriosidase activity (R = 0.621). After two years of treatment, we noticed statistically significant variations in chitotriosidase activity corresponding to the most frequent genotypes (N370S/ unknown allele, N370S/L444P, N370S/N370S and N370S/R463Q). Conclusions: Allele distribution displayed specific features in Romanian GD patients, such as the high prevalence of the N370S allele. Chitotriosidase activity measurement allowed the investigation of genotype influence on treatment outcome.

Development of a new tandem mass spectrometry method for urine and amniotic fluid screening of oligosaccharidoses

RATIONALE

The first step in the diagnosis of oligosaccharidoses is to evidence abnormal oligosaccharides excreted in urine, usually performed by the poorly sensitive but efficient thin layer chromatography (TLC) method. Developing a tandem mass spectrometry (MS/MS) technique could be of great interest to replace TLC.

METHODS

Abnormal underivatized oligosaccharides have been recently studied using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, allowing the unambiguous identification of oligosaccharidoses. Based on this previous work, we developed an advantageous and efficient liquid chromatography (LC)/MS/MS method using a more common triple quadrupole tandem mass spectrometer for oligosaccharides analysis.

RESULTS

Oligosaccharidoses (n = 97) and control (n = 240) urine samples were analysed. A specific pattern was obtained for each oligosaccharidosis using this method. In urine, it allows not only the identification of all the oligosaccharidoses previously identified by TLC (fucosidosis, alphamannosidosis, aspartylglucosaminuria, GM1 gangliosidosis, sialidosis, galactosialidosis and Schindler disease), but also extends the field of diagnosis to mucolipidosis type II, Sandhoff disease, and β-mannosidosis. The same technique was applied to 16 amniotic fluid supernatants from oligosaccharidosis-affected foetuses (n = 16) compared with 37 unaffected. All the affected foetuses could be clearly identified: sialidosis (n = 3), galactosialidosis (n = 4), aspartylglucosaminuria (n = 1), mucolipidosis type II (n = 4) or GM1 gangliosidosis (n = 4). This technique can be applied to early prenatal diagnosis as well as to the oligosaccharidosis screening in the case of non-immune hydrops fetalis.

CONCLUSIONS

The method is quick and easy to run, with an LC analysis time of 13 min per sample. The quantitative validation could not be obtained in the absence of a specific standard and of a labelled internal standard for each compound. Even if this LC/MS/MS method is only qualitative, it is very specific and much more sensitive than TLC. It allows the urinary screening of oligosaccharidoses, even mild or late-onset forms, and the screening of antenatal forms in amniotic fluid. Copyright © 2017 John Wiley & Sons, Ltd.

A Review of Gaucher Disease Pathophysiology, Clinical Presentation and Treatments

Gaucher disease (GD, ORPHA355) is a rare, autosomal recessive genetic disorder. It is caused by a deficiency of the lysosomal enzyme, glucocerebrosidase, which leads to an accumulation of its substrate, glucosylceramide, in macrophages. In the general population, its incidence is approximately 1/40,000 to 1/60,000 births, rising to 1/800 in Ashkenazi Jews. The main cause of the cytopenia, splenomegaly, hepatomegaly, and bone lesions associated with the disease is considered to be the infiltration of the bone marrow, spleen, and liver by Gaucher cells. Type-1 Gaucher disease, which affects the majority of patients (90% in Europe and USA, but less in other regions), is characterized by effects on the viscera, whereas types 2 and 3 are also associated with neurological impairment, either severe in type 2 or variable in type 3. A diagnosis of GD can be confirmed by demonstrating the deficiency of acid glucocerebrosidase activity in leukocytes. Mutations in the GBA1 gene should be identified as they may be of prognostic value in some cases. Patients with type-1 GD-but also carriers of GBA1 mutation-have been found to be predisposed to developing Parkinson's disease, and the risk of neoplasia associated with the disease is still subject to discussion. Disease-specific treatment consists of intravenous enzyme replacement therapy (ERT) using one of the currently available molecules (imiglucerase, velaglucerase, or taliglucerase). Orally administered inhibitors of glucosylceramide biosynthesis can also be used (miglustat or eliglustat).

Long-term exposure to Myozyme results in a decrease of anti-drug antibodies in late-onset Pompe disease patients

Immunogenicity of recombinant human acid-alpha glucosidase (rhGAA) in enzyme replacement therapy (ERT) is a safety and efficacy concern in the management of late-onset Pompe disease (LOPD). However, long-term effects of ERT on humoral and cellular responses to rhGAA are still poorly understood. To better understand the impact of immunogenicity of rhGAA on the efficacy of ERT, clinical data and blood samples from LOPD patients undergoing ERT for >4 years (n = 28) or untreated (n = 10) were collected and analyzed. In treated LOPD patients, anti-rhGAA antibodies peaked within the first 1000 days of ERT, while long-term exposure to rhGAA resulted in clearance of antibodies with residual production of non-neutralizing IgG. Analysis of  T cell responses to rhGAA showed detectable T cell reactivity only after in vitro restimulation. Upregulation of several cytokines and chemokines was detectable in both treated and untreated LOPD subjects, while IL2 secretion was detectable only in subjects who received ERT. These results indicate that long-term ERT in LOPD patients results in a decrease in antibody titers and residual production of non-inhibitory IgGs. Immune responses to GAA following long-term ERT do not seem to affect efficacy of ERT and are consistent with an immunomodulatory effect possibly mediated by regulatory T cells.

Obstructive sleep apnea syndrome after hematopoietic stem cell transplantation in children with mucopolysaccharidosis type I

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is very common in mucopolysaccharidosis I (MPS I). Hematopoietic stem cell transplantation (HSCT) is the preferred treatment for patients with severe MPS I diagnosed early in life. The protective effect of HSCT on the development of long term OSAS is not known.

METHODS

Overnight polysomnography (PSG) and biomarker data were analyzed during the annual follow-up in consecutive MPS I patients treated with HSCT.

RESULTS

The data of 13 patients (6 boys) were analyzed. Median age at HSCT was 17 (range 14-19) months, median age at PSG was 9.0 (4.5-14.5) years, and median time elapsed since HSCT was 7.6 (2.4-13.2) years. A significant correlation was observed between time elapsed since HSCT and the apnea-hypopnea index (AHI, r(2)=0.493, p=+0.003) and the oxygen desaturation index (r(2)=0.424, p=+0.02). Patients older than 10 years of age had a higher mean AHI (25.8/h vs 1.4/h, p=0.0008), a lower mean pulse oximetry (94.7% vs 97.2%, p=0.01) and a higher mean hypopnea index (18.8 vs 0.71/h, p=0.016) as compared to those younger than 10 years of age. No correlation was observed between the AHI and the metabolic clearance, assessed by urine glycosaminoglycan (GAG) excretion and residual enzyme activity, although there was a positive trend for the urinary GAG/higher normal value for age ratio (p=0.09).

CONCLUSION

HSCT does not offer long term protection against OSAS in MPS I with OSAS being documented in all patients after a time elapse since HSCT exceeding 10 years. The potential benefit of additional enzyme replacement therapy needs to be assessed.

Neuroblastoma Amplified Sequence (NBAS) mutation in recurrent acute liver failure: Confirmatory report in a sibship with very early onset, osteoporosis and developmental delay

BACKGROUND

Recently, biallelic mutations in the Neuroblastoma Amplified Sequence NBAS gene have been identified in ten patients that present recurrent acute liver failure (RALF) in early infancy. In addition to severe liver dysfunction, some of these individuals also suffered from other comorbidities including cardiomyopathy, neurologic phenotypes and gastrointestinal immune defects. Here we report on a consanguineous Lebanese family with three siblings affected by RALF. Of note, neonatal spontaneous fractures, developmental delay, prominent eyes, generalized hirsutism, gum hypertrophy, and hepato-splenomegaly ​were also present.

METHODS

Whole-genome SNP genotyping in all the patients, followed by exome sequencing was performed in one of the affected siblings.

RESULTS

A homozygous c.409C > T (p.Arg137Trp) missense mutation in NBAS was identified in all patients.

CONCLUSION

Overall, our findings confirm the involvement of NBAS in the pathogenesis of this condition characterized by severe liver dysfunction and help expand its phenotypical spectrum.

Moderate- and high-intensity exhaustive exercise in the heat induce a similar increase in monocyte Hsp72

This study examined the relationship between exhaustive exercise in the heat at moderate and high intensities on the intracellular heat shock protein 72 (iHsp72) response. Twelve male subjects cycled to exhaustion at 60 and 75% of maximal oxygen uptake in hot conditions (40 °C, 50% RH). iHsp72 concentration was measured in monocytes before, at exhaustion and 24 h after exercise. Rectal temperature, heart rate and oxygen uptake were recorded during exercise. Volitional exhaustion occurred at 58.9 ± 12.1 and 27.3 ± 9.5 min (P < 0.001) and a rectal temperature of 39.8 ± 0.4 and 39.2 ± 0.6 °C (P = 0.002), respectively, for 60 and 75 %. The area under the curve above a rectal temperature of 38.5 °C was greater at 60 % (17.5 ± 6.6 °C min) than 75 % (3.4 ± 4.8 °C min; P < 0.001), whereas the rate of increase in rectal temperature was greater at 75 % (5.1 ± 1.7 vs. 2.2 ± 1.4 °C h(-1); P < 0.001). iHsp72 concentration increased similarly at exhaustion relative to pre-exercise (P = 0.044) and then increased further at 24 h (P < 0.001). Multiple regression analysis revealed no predictor variables associated with iHsp72 expression; however, a correlation was observed between exercise intensities for the increase in iHsp expression at exhaustion and 24 h (P < 0.05). These results suggest that iHsp72 expression increased in relation to the level of hyperthermia attained and sustained at 60 % and the higher metabolic rate and greater rate of increase in core temperature at 75 %, with the further increase in iHsp72 concentration 24 h after exercise reinforcing its role as a chaperone and cytoprotective agent.

IFT81, encoding an IFT-B core protein, as a very rare cause of a ciliopathy phenotype

Background

Bidirectional intraflagellar transport (IFT) consists of two major protein complexes, IFT-A and IFT-B. In contrast to the IFT-B complex, all components of IFT-A have recently been linked to human ciliopathies when defective. We therefore hypothesised that mutations in additional IFT-B encoding genes can be found in patients with multisystemic ciliopathies.

Methods

We screened 1628 individuals with reno-ocular ciliopathies by targeted next-generation sequencing of ciliary candidate genes, including all IFT-B encoding genes.

Results

Consequently, we identified a homozygous mutation in IFT81 affecting an obligatory donor splice site in an individual with nephronophthisis and polydactyly. Further, we detected a loss-of-stop mutation with extension of the deduced protein by 10 amino acids in an individual with neuronal ceroid lipofuscinosis-1. This proband presented with retinal dystrophy and brain lesions including cerebellar atrophy, a phenotype to which the IFT81 variant might contribute. Cultured fibroblasts of this latter affected individual showed a significant decrease in ciliated cell abundance compared with controls and increased expression of the transcription factor GLI2 suggesting deranged sonic hedgehog signalling.

Conclusions

This work describes identification of mutations of IFT81 in individuals with symptoms consistent with the clinical spectrum of ciliopathies. It might represent the rare case of a core IFT-B complex protein found associated with human disease. Our data further suggest that defects in the IFT-B core are an exceedingly rare finding, probably due to its indispensable role for ciliary assembly in development.

Natural disease history and characterisation of SUMF1 molecular defects in ten unrelated patients with multiple sulfatase deficiency

BACKGROUND

Multiple sulfatase deficiency is a rare inherited metabolic disorder caused by mutations in the SUMF1 gene. The disease remains poorly known, often leading to a late diagnosis. This study aimed to provide improved knowledge of the disease, through complete clinical, biochemical, and molecular descriptions of a cohort of unrelated patients. The main objective was to identify prognostic markers, both phenotypic and genotypic, to accelerate the diagnosis and improve patient care.

METHODS

The phenotypes of ten unrelated patients were fully documented at the clinical and biochemical levels. The long-term follow-up of each patient allowed correlations of the phenotypes to the disease outcomes. Each patient's molecular defects were also identified. Site-directed mutagenesis was used to individually express the mutants and assess their stability. Characterisation of the protein mutants was completed by in silico analyses based on sequence comparisons and structural models.

RESULTS

The most severe cases were characterised by the presence of non-neurological symptoms as well as the occurrence of psychomotor regression before 2 years of age. Nine novel SUMF1 mutations were identified. Clinically severe forms were often associated with SUMF1 mutations that strongly affected the protein stability and/or catalytic function as predicted from in silico and western blot analyses.

CONCLUSIONS

This detailed clinical description and follow-up of a cohort of patients, together with the molecular characterisation of their underlying defects, contribute to improved knowledge of multiple sulfatase deficiency. Predictors of a bad prognosis were the presence of several non-neurological symptoms and the onset of psychomotor regression before 2 years of age. No strict correlation existed between in vitro residual sulfatase activity and disease severity. Genotype-phenotype correlations related to previously reported mutants were strengthened. These and previous observations allow not only improved prediction of the disease outcome but also provision of appropriate care for patients, in the expectation of specific treatment development.

Modeling changes in biomarkers in Gaucher disease patients receiving enzyme replacement therapy using a pathophysiological model

Background

Gaucher disease (GD) is a rare recessively inherited disorder caused by deficiency of a lysosomal enzyme, glucocerebrosidase. Accumulation of glucosylceramide or glucosylsphingosine in macrophages leads to increased production of ferritin and chitotriosidase and to decreases in hemoglobin concentration and platelet count, which are used as blood biomarkers. GD is treated by enzyme replacement therapy (ERT) or, sometimes by substrate reduction therapy. However, no physiological model for analysis of biomarkers change during ERT has been proposed. We aimed to develop a pathophysiological model to analyze biomarker’s response to ERT and several covariates impact.

Methods

Changes in blood ferritin, chitotriosidase, hemoglobin and platelets were analyzed in French GD Registry patients receiving imiglucerase/alglucerase as ERT. We used simplified exponential pathophysiological model, with initial concentration, biomarkers amplitude of variation and rate constant of normalization during ERT. Changes in four biomarkers were analyzed separately and then all four together from initiation to discontinuation of ERT, or until the end of follow-up. Several covariates were tested, including age at ERT initiation, splenectomy, sex, genotype (N370S/N370S), and ERT dose.

Results

An exponential model gave a good data fit. The four biomarkers analysis showed that the rate of nomalization was the same for all biomarkers, with a half-life of 0.5 years. Predicted values of biomarkers at ERT’s steady state were 40% and 10% of initial concentrations, for ferritin and chitotriosidase, respectively, and 120% and 200% for hemoglobin and platelets, respectively. We found that 3 covariates had an effect on initial concentration or on amplitude of variation in ferritin, hemoglobin and platelets: women and patients under 15 years of age had lower ferritin and hemoglobin concentrations, and patients under 15 years of age had higher platelet count. Splenectomized patients had higher ferritin concentrations and platelet count and lower amplitude of variation of hemoglobin.

Conclusion

We report the first dynamic model of biomarker changes in GD. It enabled us to estimate that 95% of biomarker response to ERT was achieved in 2 years, but with high inter-patient variability. We also found that with the current treatment, normalization of chitotriosidase and ferritin will occur in about 65% of patients.

Large-mode-area infrared guiding in ultrafast laser written waveguides in sulfur-based chalcogenide glasses

Current demands in astrophotonics impose advancing optical functions in infrared domains within embedded refractive index designs. We demonstrate concepts for large-mode-area guiding in ultrafast laser photowritten waveguides in bulk Sulfur-based chalcogenide glasses. If positive index contrasts are weak in As2S3, Ge doping increases the matrix rigidity and allows for high contrast (10(-3)) positive refractive index changes. Guiding with variable mode diameter and large-mode-area light transport is demonstrated up to 10 μm spectral domain using transverse slit-shaped and evanescently-coupled multicore traces.

A prospective study of bone marrow hematopoietic and mesenchymal stem cells in type 1 Gaucher disease patients

Gaucher disease (GD) is an autosomal recessive disorder characterized by lysosomal glucocerebrosidase (GBA) deficiency leading to hematological and skeletal manifestations. Mechanisms underlying these symptoms have not yet been elucidated. In vivo, bone marrow (BM) mesenchymal stem cells (MSCs) have important role in the regulation of bone mass and in the support of hematopoiesis, thus representing potential candidate that could contribute to the disease. GBA deficiency may also directly impair hematopoietic stem/progenitors cells (HSPCs) intrinsic function and induce hematological defect. In order to evaluate the role of BM stem cells in GD pathophysiology, we prospectively analyzed BM-MSCs and HSPCs properties in a series of 10 patients with type 1 GD. GBA activity was decreased in all tested cell subtypes. GD-MSCs had an impaired growth potential, morphological and cell cycle abnormalities, decreased capacities to differentiate into osteoblasts. Moreover, GD-MSCs secreted soluble factors that stimulated osteoclasts resorbing activities. In vitro and in vivo primitive and mature hematopoiesis were similar between patients and controls. However, GD-MSCs had a lower hematopoietic supportive capacity than those from healthy donors. These data suggest that BM microenvironment is altered in GD and that MSCs are key components of the manifestations observed in GD.

Defects of Vps15 in skeletal muscles lead to autophagic vacuolar myopathy and lysosomal disease

The complex of Vacuolar Protein Sorting 34 and 15 (Vps34 and Vps15) has Class III phosphatidylinositol 3-kinase activity and putative roles in nutrient sensing, mammalian Target Of Rapamycin (mTOR) activation by amino acids, cell growth, vesicular trafficking and autophagy. Contrary to expectations, here we show that Vps15-deficient mouse tissues are competent for LC3-positive autophagosome formation and maintain mTOR activation. However, an impaired lysosomal function in mutant cells is traced by accumulation of adaptor protein p62, LC3 and Lamp2 positive vesicles, which can be reverted to normal levels after ectopic overexpression of Vps15. Mice lacking Vps15 in skeletal muscles, develop a severe myopathy. Distinct from the autophagy deficient Atg7^−/− mutants, pathognomonic morphological hallmarks of autophagic vacuolar myopathy (AVM) are observed in Vps15^−/− mutants, including elevated creatine kinase plasma levels, accumulation of autophagosomes, glycogen and sarcolemmal features within the fibres. Importantly, Vps34/Vps15 overexpression in myoblasts of Danon AVM disease patients alleviates the glycogen accumulation. Thus, the activity of the Vps34/Vps15 complex is critical in disease conditions such as AVMs, and possibly a variety of other lysosomal storage diseases.

[Molecular diagnosis of Gaucher disease in Tunisia]

Gaucher disease is a lysosomal storage disorder caused by a deficiency of the enzyme acid β-glucosidase. In order to determine the mutation spectrum in Tunisia, we performed recurrent mutation screening in 30 Tunisian patients with Gaucher disease. Screening of recurrent mutation by PCR/RFLP and direct sequencing had shown that N370S was the most frequent mutation (22/50 mutant alleles, 44%), followed by L444P mutation, which is found in 16% (8/50 mutant alleles). The recombinant allele (RecNciI) represented 14%. Our findings revealed that the genotype N370S/RecNciI was mosst frequent in patients with childhood onset and it was associated with severe visceral involvement. The screening of these three mutations provided a simple tool for molecular diagnosis of Gaucher disease in Tunisian patients and allowed also genetic counselling for their family members.

The French Gaucher's disease registry: clinical characteristics, complications and treatment of 562 patients

Background

Clinical features, complications and treatments of Gaucher’s disease (GD), a rare autosomal–recessive disorder due to a confirmed lysosomal enzyme (glucocerebrosidase) deficiency, are described.

Methods

All patients with known GD, living in France, with ≥1 consultations (1980–2010), were included in the French GD registry, yielding the following 4 groups: the entire cohort, with clinical description; and its subgroups: patients with ≥1 follow-up visits, to investigate complications; recently followed (2009–2010) patients; and patients treated during 2009–2010, to examine complications before and during treatment. Data are expressed as medians (range) for continuous variables and numbers (%) for categorical variables.

Results

Among the 562 registry patients, 265 (49.6%) were females; 454 (85.0%) had type 1, 22 (4.1%) type 2, 37 (6.9%) perinatal–lethal type and 21 (3.9%) type 3. Median ages at first GD symptoms and diagnosis, respectively, were 15 (0–77) and 22 (0–84) years for all types. The first symptom diagnosing GD was splenomegaly and/or thrombocytopenia (37.6% and 26.3%, respectively). Bone-marrow aspiration and/or biopsy yielded the diagnosis for 54.7% of the patients, with enzyme deficiency confirming GD for all patients. Birth incidence rate was estimated at 1/50,000 and prevalence at 1/136,000. For the 378 followed patients, median follow-up was 16.2 (0.1–67.6) years. Major clinical complications were bone events (BE; avascular necrosis, bone infarct or pathological fracture) for 109 patients, splenectomy for 104, and Parkinson’s disease for 14; 38 patients died (neurological complications for 15 type-2 and 3 type-3 patients, GD complications for 11 type-1 and another disease for 9 type-1 patients). Forty-six had monoclonal gammopathy. Among 283 recently followed patients, 36 were untreated and 247 had been treated during 2009–2010; 216 patients received treatment in December 2010 (126 with imiglucerase, 45 velaglucerase, 24 taliglucerase, 21 miglustat). BE occurred before (130 in 67 patients) and under treatment (60 in 41 patients) with respective estimated frequencies (95% CI) of first BE at 10 years of 20.3% (14.1%–26.5%) and 19.8% (13.5%–26.1%).

Conclusion

This registry enabled the epidemiological description of GD in France and showed that BE occur even during treatment.

Characterization of seven novel mutations on the HEXB gene in French Sandhoff patients

Sandhoff disease (SD) is an autosomal recessive lysosomal storage disease caused by mutations in the HEXB gene encoding the beta subunit of hexosaminidases A and B, two enzymes involved in GM2 ganglioside degradation. Eleven French Sandhoff patients with infantile or juvenile forms of the disease were completely characterized using sequencing of the HEXB gene. A specific procedure was developed to facilitate the detection of the common 5'-end 16kb deletion which was frequent (36% of the alleles) in our study. Eleven other disease-causing mutations were found, among which four have previously been reported (c.850C>T, c.793T>G, c.115del and c.800_817del). Seven mutations were completely novel and were analyzed using molecular modelling. Two deletions (c.176del and c.1058_1060del), a duplication (c.1485_1487dup) and a nonsense mutation (c.552T>G) were predicted to strongly alter the enzyme spatial organization. The splice mutation c.558+5G>A affecting the intron 4 consensus splice site led to a skipping of exon 4 and to a truncated protein (p.191X). Two missense mutations were found among the patients studied. The c.448A>C mutation was probably a severe mutation as it was present in association with the known c.793T>G in an infantile form of Sandhoff disease and as it significantly modified the N-terminal domain structure of the protein. The c.171G>C mutation resulting in a p.W57C amino acid substitution in the N-terminal region is probably less drastic than the other abnormalities as it was present in a juvenile patient in association with the c.176del. Finally, this study reports a rapid detection of the Sandhoff disease-causing alleles facilitating genetic counselling and prenatal diagnosis in at-risk families.

Effect of an 8-weeks aerobic training program in elderly on oxidative stress and HSP72 expression in leukocytes during antioxidant supplementation

OBJECTIVE

To investigate the effect of aerobic training in the context of antioxidant supplementation on systemic oxidative stress and leukocytes heat shock protein (Hsp)72 expression in the elderly.

DESIGN

Sixteen septuagenarians (8 males and 8 females, mean age 74.6) were supplemented with Vitamin C and E (respectively 500 and 100mg per day) and randomly assigned either to sedentary (AS) or individualized aerobically trained (AT) group for 8 weeks.

METHODS

Plasma Vitamin C and E concentrations and aerobic fitness, as well as resting and post graded exercise (GXT) Hsp72 expression in leukocytes, plasma levels of thiobarbituric acid reactive substances (TBARS) and advanced oxidation protein product (AOPP) were measured pre and post training / supplementation.

RESULTS

At the end of the intervention, the two groups showed a significant increase in resting plasma vitamin C and E (approximately 50 and 20% increase respectively) and a significant decrease in both resting and post GXT plasma TBARS and AOPP (approximately 25 and 20% decrease respectively). These changes were of similar magnitude in the two groups. The reduced oxidative stress was concomitant with a 15% decreased expression of Hsp72 in monocytes and granulocytes in both groups.

CONCLUSION

This study provides evidence that in elderly, increased concentration of antioxidant vitamins C and E is associated with a reduction in oxidative stress and leukocytes Hsp72. In this context, 8 weeks of aerobic training has no impact on oxidative stress or leukocytes Hsp72 expression in elderly people.

Bone marrow microenvironment in an in vitro model of Gaucher disease: consequences of glucocerebrosidase deficiency

Gaucher disease (GD) is a lysosomal storage disorder due to glucocerebrosidase (GBA) deficiency. Mechanisms leading to the emergence of hematological and skeletal manifestations observed in GD are poorly explained. Bone marrow (BM) mesenchymal stem cells (MSCs) are multipotent progenitors that participate in the regulation of bone mass. MSCs should thus represent a cell population involved in the development or progression of bone disease in GD. In a chemical model of GD obtained with Conduritol β epoxide (CBE), a specific inhibitor of GBA activity, we functionally characterized BM MSCs and specifically analyzed their capacity to differentiate into osteoblasts. GBA deficiency obtained with CBE treatment, leads to a dramatic impairment of MSCs proliferation and to morphological abnormalities. Although the capacity of MSCs to differentiate into osteoblasts was not modified, the levels of several soluble factors that regulate bone metabolism were increased in MSCs treated with CBE, compared with untreated MSCs. Moreover, addition of conditioned media from CBE-treated MSCs on monocyte-derived osteoclasts cultured on bone matrix leads to an increase of resorption areas. These data suggested that, in GD, MSCs represents a stem cell population that is likely to be involved in bone pathogenesis.

New insights into therapeutic options for Pompe disease

Glycogen storage disease type II or Pompe disease (GSD II, MIM 232300) is a rare inherited metabolic myopathy caused by a deficiency of lysosomal acid α-glucosidase or acid maltase (GAA; EC 3.2.1.20), resulting in a massive lysosomal glycogen accumulation in cardiac and skeletal muscles. Affected individuals exhibit either severe hypotonia associated with hypertrophic cardiomyopathy (infantile forms) or progressive muscle weakness (late-onset forms). Even if enzyme replacement therapy has recently become a standard treatment, it suffers from several limitations. This review will present the main results of enzyme replacement therapy and the recent findings concerning alternative treatments for Pompe disease, such as gene therapy, enzyme enhancement therapy, and substrate reduction therapy.