Uncertain diagnosis of fabry disease in patients with neuropathic pain, angiokeratoma or cornea verticillata: consensus on the approach to diagnosis and follow-up.

INTRODUCTION: Individuals with neuropathic pain, angiokeratoma (AK) and/or cornea verticillata (CV) may be tested for Fabry disease (FD). Classical FD is characterised by a specific pattern of these features. When a patient presents with a non-specific pattern, the pathogenicity of a variant in the α-galactosidase A (GLA) gene may be unclear. This uncertainty often leads to considerable distress and inappropriate counselling and treatment. We developed a clinical approach for these individuals with an uncertain diagnosis of FD. MATERIALS AND METHODS: A document was presented to an FD expert panel with background information based on clinical experience and the literature, followed by an online survey and a written recommendation. RESULTS: The 13 experts agreed that the recommendation is intended for individuals with neuropathic pain, AK and/or CV only, i.e. without kidney, heart or brain disease, with an uncertain diagnosis of FD. Only in the presence of FD-specific neuropathic pain (small fibre neuropathy with FD-specific pattern), AK (FD-specific localisations) or CV (without CV inducing medication), FD is confirmed. When these features have a non-specific pattern, there is insufficient evidence for FD. If no alternative diagnosis is found, follow-up is recommended. CONCLUSIONS: In individuals with an uncertain diagnosis of FD, the presence of an FD-specific pattern of CV, AK or neuropathic pain is sufficient to confirm the diagnosis of FD. When these features are non-specific, a definite diagnosis cannot (yet) be established and follow-up is indicated. ERT should be considered only in those patients with a confirmed diagnosis of FD.

Modelling Gaucher disease progression: long-term enzyme replacement therapy reduces the incidence of splenectomy and bone complications.

Long-term complications and associated conditions of type 1 Gaucher Disease (GD) can include splenectomy, bone complications, pulmonary hypertension, Parkinson disease and malignancies. Enzyme replacement therapy (ERT) reverses cytopenia and reduces organomegaly. To study the effects of ERT on long-term complications and associated conditions, the course of Gaucher disease was modelled.

Evaluation of miglustat as maintenance therapy after enzyme therapy in adults with stable type 1 Gaucher disease: a prospective, open-label non-inferiority study.

BACKGROUND: Previous studies have provided equivocal data on the use of miglustat as maintenance therapy in Gaucher disease type 1. We report findings from a clinical trial evaluating the effects of miglustat treatment in patients with stable type 1 Gaucher disease after enzyme therapy. METHODS: Adult type 1 Gaucher disease patients stabilized during at least 3 years of previous enzyme therapy were included in this 2-year, prospective, open-label non-inferiority study. The primary endpoint was percent change from baseline in liver volume. Secondary endpoints included changes in spleen volume, hemoglobin concentration and platelet count. RESULTS: Forty-two patients were enrolled (mean±SD age, 45.1±12.7 years; previous enzyme therapy duration 9.5±4.0 years). Median (range) exposure to miglustat 100 mg t.i.d. was 658 (3-765) days. Twenty-one patients discontinued treatment prematurely; 13 due to adverse events, principally gastrointestinal. The upper 95% confidence limit of mean percent change in liver volume from baseline to end of treatment was below the non-inferiority margin of 10% (-1.1%; 95%CI -6.0, 3.9%). Mean (95%CI) changes in spleen volume, hemoglobin concentration and platelet count were 102 (24,180) mL, -0.95 (-1.38, -0.53) g/dL and -44.1 (-57.6, -30.7) ×109/L, respectively. CONCLUSIONS: The primary efficacy endpoint was met; overall there was no change in liver volume during 24 months of miglustat therapy. Several patients showed a gradual deterioration in some disease manifestations, suggesting that miglustat could maintain clinical stability, but not in all patients. Miglustat demonstrated a predictable profile of safety and tolerability that was consistent with that reported in previous clinical trials and experience in clinical practice. TRIAL REGISTRATION: Clinicaltrials.gov identifier NCT00319046.

An evidence-based review of the potential benefits of taliglucerase alfa in the treatment of patients with Gaucher disease.

Gaucher disease is an inherited lysosomal storage disorder, characterized by deficient activity of glucocerebrosidase leading to storage of glucocerebroside in tissue macrophages. Type I disease, the most prevalent form, lacks central nervous system involvement but presents primarily with variable degrees of hepatosplenomegaly, cytopenia, and bone disease. Intravenous enzyme replacement therapy can reverse these manifestations. In addition to the two enzymes currently authorized for use, the newest enzyme, taliglucerase alfa, is at the late stages of clinical development. Taliglucerase alfa is a unique product, as it is the first plant cell-based recombinant enzyme therapy. This review considers the existing evidence for therapeutic efficacy of taliglucerase alfa in the treatment of the non-neuronopathic manifestations of Gaucher disease. Clinical studies encompass one phase I trial in healthy volunteers, one phase III trial, and preliminary results from both an extension study and a switch study. In the 9-month, randomized, double-blind phase III trial, treatment-naïve patients with type I Gaucher disease were treated with either 30 or 60 U/kg every 2 weeks. Dose-dependent improvements were achieved after 6 and 9 months of therapy, with reductions in spleen and liver volumes and improvements in hemoglobin levels. Platelet counts improved initially only in the higher-dose group, but preliminary results from the extension study also show significant increases in the lower-dose group. Bone marrow involvement, as assessed by magnetic resonance imaging, improved in almost all patients. Taliglucerase alfa has shown a good safety profile, with few patients experiencing hypersensitivity reactions and developing antibodies. An additional enzyme replacement therapy for Gaucher disease would enable the treatment of more patients and would provide backup for unexpected production problems. Furthermore, it is expected that this new treatment would reduce the costs of therapy. Taliglucerase alfa is a valuable new treatment modality for the non-neuronopathic manifestations of Gaucher disease.

"MY PKU": increasing self-management in patients with phenylketonuria. A randomized controlled trial.

BACKGROUND: Phenylketonuria (PKU) is an autosomal recessive disorder of phenylalanine metabolism. The inability to convert phenylalanine (Phe) into tyrosine causes Phe to accumulate in the body. Adherence to a protein restricted diet, resulting in reduced Phe levels, is essential to prevent cognitive decline. Frequent evaluation of plasma Phe levels and, if necessary, adjustment of the diet are the mainstay of treatment. We aimed to assess whether increased self-management of PKU patients and/or their parents is feasible and safe, by providing direct online access to blood Phe values without immediate professional guidance. METHODS: Thirty-eight patients aged ≥ 1 year participated in a 10 month randomized controlled trial. Patients were randomized into a study group (1) or a control group (2). Group 2 continued the usual procedure: a phone call or e-mail by a dietician in case of a deviant Phe value. Group 1 was given a personal "My PKU" web page with a graph of their recent and previous Phe values, online general information about the dietary treatment and the Dutch PKU follow-up guidelines, and a message-box to contact their dietician if necessary. Phe values were provided on "My PKU" without advice. Outcome measures were: differences in mean Phe value, percentage of values above the recommended range and Phe sample frequency, between a 10-month pre-study period and the study period in each group, and between the groups in both periods. Furthermore we assessed satisfaction of patients and/or parents with the 'My PKU' procedure of online availability. RESULTS: There were no significant differences in mean Phe value, percentage of values above recommended range or in frequency of blood spot sampling for Phe determination between the pre-study period and the study period in each group, nor between the 2 groups during the periods. All patients and/or parents expressed a high level of satisfaction with the new way of disease management. CONCLUSIONS: Increased self-management in PKU by providing patients and/or parents their Phe values without advice is feasible and safe and is highly appreciated. TRIAL REGISTRATION: The trial was registered with The Netherlands National Trial Register (NTR #1171) before recruitment of patients.