Laronidase for cardiopulmonary disease in Hurler syndrome 12 years after bone marrow transplantation

A patient with severe mucopolysaccharidosis type I (Hurler syndrome) underwent bone marrow transplantation twice (at the ages of 2 and 2.5 years), both times with his HLA-identical heterozygous brother as the donor. Between the ages of 10 and 14 years, despite 92% donor engraftment and 50% normal α-L-iduronidase activity, he developed progressive respiratory failure with severe pulmonary arterial hypertension, upper airway obstruction, and interstitial lung disease. Noninvasive ventilation and weekly laronidase therapy were initiated. Within 24 months, his mean pulmonary artery pressure was within the upper limit of normal and interstitial lung disease and airway obstruction improved markedly. He went from using a wheelchair to having full ambulation, he no longer required daytime ventilation, and his quality-of-life scores (Child Health Assessment Questionnaire) significantly improved.     

Functional and electrophysiological characterization of four non-truncating mutations responsible for creatine transporter (SLC6A8) deficiency syndrome

Intellectual disability coupled with epilepsy are clinical hallmarks of the creatine (Cr) transporter deficiency syndrome resulting from mutations in the SLC6A8 gene. So far characterization of pathogenic mutations of SLC6A8 has been limited to Cr uptake. The aim of our study was to characterize the electrogenic and pharmacological properties of non truncating SLC6A8 mutations identified in patients presenting variable clinical severity. Electrophysiological and pharmacological properties of four mutants (including two novel ones) were studied in X. laevis oocyte expression system. Creatine uptake was assessed with [¹⁴C]-Cr in X. laevis and patients’ fibroblasts. Subcellular localization was determined by immunofluorescence and western blot. All mutants were properly targeted to the plasma membrane in both systems. Mutations led to the complete loss of both electrogenic and transport activities in X. laevis and Cr uptake in patients’ fibroblasts. Among the Cr analogs tested, guanidinopropionate induced an electrogenic activity with the normal SLC6A8 transporter similar to creatine whereas a phosphocreatine derivative, PCr-Mg-CPLX, resulted in partial activity. SLC6A8 mutants displayed no electrogenic activity with all Cr analogs tested in X. laevis oocytes. Although the mutations altered various domains of SLC6A8 Cr uptake and electrogenic properties were completely inhibited and could not be dissociated. Besides the metabolic functions of Cr, the loss of SLC6A8 electrogenic activity, demonstrated here for the first time, may also play a role in the altered brain functions of the patients.     

Human thymic stromal lymphopoietin: a novel epithelial cell-derived cytokine and a potential key player in the induction of allergic inflammation

Allergy is the result of a complex immune cascade leading to the dysregulated production of Th2 cytokines, the generation of allergen-specific IgE-producing B cells and the subsequent activation and degranulation of mast cells upon allergen challenge. Dendritic cells (DCs) play an important role in several models of allergy, but factors instructing DCs to induce a dysregulated Th2 response are currently unknown. In this review, we present recent evidence that human thymic stromal lymphopoietin (TSLP), a novel IL-7-like cytokine, might represent an early trigger of the allergic immune cascade. TSLP-activated human DCs produce Th2-attracting chemokines but no IL-12, and induce naive CD4⁺ and CD8⁺ T cell differentiation into effector cells with a typical pro-allergic phenotype. TSLP is produced by human epithelial, stromal, and mast cells. It is highly expressed by the keratinocytes of atopic dermatitis but not in other types of skin inflammation. Thus, epithelial- and stromal-cell-derived TSLP might represent one of the factors initiating the allergic responses, and could be a target for a curative therapeutic approach to allergy.     

Glycogen Storage Disease Type Ia: Current Management Options,Burden and Unmet Needs

Glycogen storage disease type Ia (GSDIa) is caused by defective glucose-6-phosphatase, a key enzyme in carbohydrate metabolism. Affected individuals cannot release glucose during fasting and accumulate excess glycogen and fat in the liver and kidney, putting them at risk of severe hypoglycaemia and secondary metabolic perturbations. Good glycaemic/metabolic control through strict dietary treatment and regular doses of uncooked cornstarch (UCCS) is essential for preventing hypoglycaemia and long-term complications. Dietary treatment has improved the prognosis for patients with GSDIa; however, the disease itself, its management and monitoring have significant physical, psychological and psychosocial burden on individuals and parents/caregivers. Hypoglycaemia risk persists if a single dose of UCCS is delayed/missed or in cases of gastrointestinal intolerance. UCCS therapy is imprecise, does not treat the cause of disease, may trigger secondary metabolic manifestations and may not prevent long-term complications. We review the importance of and challenges associated with achieving good glycaemic/metabolic control in individuals with GSDIa and how this should be balanced with age-specific psychosocial development towards independence, management of anxiety and preservation of quality of life (QoL). The unmet need for treatment strategies that address the cause of disease, restore glucose homeostasis, reduce the risk of hypoglycaemia/secondary metabolic perturbations and improve QoL is also discussed.     

Liver glycogen storage diseases due to phosphorylase system deficiencies: diagnosis thanks to non invasive blood enzymatic and molecular studies

Glycogen storage disease (GSD) due to a deficient hepatic phosphorylase system defines a genetically heterogeneous group of disorders that mainly manifests in children. We investigated 45 unrelated children in whom a liver GSD VI or IX was suspected on the basis of clinical symptoms including hepatomegaly, increased serum transaminases, postprandial lactatemia and/or mild fasting hypoglycemia. Liver phosphorylase and phosphorylase b kinase activities studied in peripheral blood cells allowed to suspect diagnosis in 37 cases but was uninformative in 5. Sequencing of liver phosphorylase genes was useful to establish an accurate diagnosis. Causative mutations were found either in the PYGL (11 patients), PHKA2 (26 patients), PHKG2 (three patients) or in the PHKB (three patients) genes. Eleven novel disease causative mutations, five missense (p.N188K, p.D228Y, p.P382L, p.R491H, p.L500R) and six truncating mutations (c.501_502ins361pb, c.528+2T>C, c.856-29_c.1518+614del, c.1620+1G>C, p.E703del and c.2313-1G>T) were identified in the PYGL gene. Seventeen novel disease causative mutations, ten missense (p.A42P, p.Q95R, p.G131D, p.G131V, p.Q134R, p.G187R, p.G300V, p.G300A, p.C326Y, p.W820G) and seven truncating (c.537+5G>A, p.G396DfsX28, p.Q404X, p.N653X, p.L855PfsX87, and two large deletions) were identified in the PHKA2 gene. Four novel truncating mutations (p.R168X, p.Q287X, p.I268PfsX12 and c.272-1G>C) were identified in the PHKG2 gene and three (c.573_577del, p.R364X, c.2427+3A>G) in the PHKB gene. Patients with PHKG2 mutations evolved towards cirrhosis. Molecular analysis of GSD VI or IX genes allows to confirm diagnosis suspected on the basis of enzymatic analysis and to establish diagnosis and avoid liver biopsy when enzymatic studies are not informative in blood cells.     

Incidence and natural history of mucopolysaccharidosis type III in France and comparison with United Kingdom and Greece

Sanfilippo syndrome, or mucopolysaccharidosis type III (MPSIII) is a lysosomal storage disease with predominant neurological manifestations in affected children. It is considered heterogeneous with respect to prevalence, clinical presentation, biochemistry (four biochemical forms of the disease referred to as MPSIIIA, B, C, and D are known), and causative mutations. The perspective of therapeutic options emphasizes the need for better knowledge of MPSIII incidence and natural history. We performed parallel retrospective epidemiological studies of patients diagnosed with MSPIII in France (n = 128), UK (n = 126), and Greece (n = 20) from 1990 to 2006. Incidences ranged from 0.68 per 100,000 live‐births in France to 1.21 per 100,000 live‐births in UK. MPSIIIA, which predominates in France and UK, was absent in Greece, where most patients have MPSIIIB. The study confirmed the large allelic heterogeneity of MPSIIIA and MPSIIIB and detected several yet undescribed mutations. Analysis of clinical manifestations at diagnosis and over a 6–7 years follow‐up indicated that almost all patients, whatever the disease subtype, expressed neurological manifestations before the age of 5 years, including language acquisition delay, cognitive delay, and/or abnormal behavior. In contrast to relatively homogeneous early onset manifestations, disease progression showed significant variation depending on subtype and age at diagnosis. Different severities of disease progressions and different allele distribution between France and UK suggested that mutations are not equally deleterious, although genotype–phenotype correlation could not be established. Notwithstanding the rapidity of further clinical deterioration, all MPSIII patients suffer early onset devastating neurological manifestations that deserve early treatment when available. © 2010 Wiley‐Liss, Inc.     

Validation of a 4-item Negative Symptom Assessment (NSA-4): a short, practical clinical tool for the assessment of negative symptoms in schizophrenia

The 16‐item Negative Symptom Assessment (NSA‐16) scale is a validated tool for evaluating negative symptoms of schizophrenia. The psychometric properties and predictive power of a four‐item version (NSA‐4) were compared with the NSA‐16. Baseline data from 561 patients with predominant negative symptoms of schizophrenia who participated in two identically designed clinical trials were evaluated. Ordered logistic regression analysis of ratings using NSA‐4 and NSA‐16 were compared with ratings using several other standard tools to determine predictive validity and construct validity. Internal consistency and test–retest reliability were also analyzed. NSA‐16 and NSA‐4 scores were both predictive of scores on the NSA global rating (odds ratio = 0.83–0.86) and the Clinical Global Impressions–Severity scale (odds ratio = 0.91–0.93). NSA‐16 and NSA‐4 showed high correlation with each other (Pearson r = 0.85), similar high correlation with other measures of negative symptoms (demonstrating convergent validity), and lesser correlations with measures of other forms of psychopathology (demonstrating divergent validity). NSA‐16 and NSA‐4 both showed acceptable internal consistency (Cronbach α, 0.85 and 0.64, respectively) and test–retest reliability (intraclass correlation coefficient, 0.87 and 0.82). This study demonstrates that NSA‐4 offers accuracy comparable to the NSA‐16 in rating negative symptoms in patients with schizophrenia. Copyright © 2011 John Wiley & Sons, Ltd.