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.

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 GM2 ganglioside in the lysosome. They are caused by mutation in HEXA or HEXB causing reduced or absent activity of a lysosomal ß-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 ß-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 GM1, GM2, GM3 and GD3 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 GM2 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. GM234:1 and GM234:1/GM334:1 ratio discriminated patients from controls with 100% sensitivity and specificity. GM234:1 and GM234:1/GM334:1 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 GM234:1 and GM234:1/GM334:1 ratio with age at sampling. We propose that plasma GM2 34:1 and its ratio to GM3 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.

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.

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 ß-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.

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.

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 ß-galactosidase (ß-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.

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.

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.

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.

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 ß-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.

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.

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.

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/ß. All patients with ML α/ß 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.

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.

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 ß-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).

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.

Design of Potent Mannose 6-Phosphate Analogues for the Functionalization of Lysosomal Enzymes To Improve the Treatment of Pompe Disease.

Improving therapeutics delivery in enzyme replacement therapy (ERT) for lysosomal storage disorders is a challenge. Herein, we present the synthesis of novel analogues of mannose 6-phosphate (M6P), known as AMFAs and functionalized at the anomeric position for enzyme grafting. AMFAs are non-phosphate serum-resistant derivatives that efficiently bind the cation-independent mannose 6-phosphate receptor (CI-M6PR), which is the main pathway to address enzymes to lysosomes. One of the AMFAs was used to improve the treatment of the lysosomal myopathy Pompe disease, in which acid α-glucosidase (GAA) is defective. AMFA grafting on a M6P-free recombinant GAA led to a higher uptake of the GAA in adult Pompe fibroblasts in culture as compared to Myozyme, the M6P recombinant GAA. Moreover, the treatment of Pompe adult mice with the AMFA-grafted recombinant enzyme led to a remarkable improvement, even at low doses, in muscle functionality and regeneration, whereas Myozyme had limited efficacy.

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.