Michael Beck

Anderson-Fabry disease: clinical manifestations of disease in female heterozygotes.

Anderson–Fabry disease is a rare, X-chromosomal lipid storage disorder caused by a deficiency of lysosomal α-galactosidase A. Clinical manifestations of Anderson–Fabry disease include excruciating pain in the extremities (acroparaesthesia), skin vessel ectasia (angiokeratoma), corneal and lenticular opacity, cardiovascular disease, stroke and renal failure, only renal failure being a frequent cause of death. Heterozygote female carriers have often been reported as being asymptomatic or having an attenuated form of the disease. To evaluate the spectrum of clinical signs in heterozygotes, a comprehensive clinical examination was performed on 20 carriers of Anderson–Fabry disease. This revealed that, in addition to the skin manifestation, various other clinical manifestations of the disease are present, including acroparaesthesia, kidney dysfunction, cerebrovascular disease, and gastrointestinal and heart problems. It therefore appears that Anderson–Fabry disease affects both hemizygotes and heterozyotes and therefore should be considered to be an X-linked dominant disease.

The mainz severity Score index: a new instrument for quantifying the anderson-fabry disease phenotype, and the response of patients to enzyme replacement therapy

Anderson–Fabry disease (AFD) is an X‐linked disorder caused by deficient activity of the lysosomal enzyme α‐galactosidase A. The availability of enzyme replacement therapy (ERT) for this debilitating condition has led to the need for a convenient and sensitive instrument to monitor clinical effects in an individual patient. This study aimed to develop a scoring system – the Mainz Severity Score Index (MSSI) – to measure the severity of AFD and to monitor the clinical course of the disease in response to ERT. Thirty‐nine patients (24 males and 15 females) with AFD were assessed using the MSSI immediately before and 1 year after commencing agalsidase alfa ERT. Control data were obtained from 23 patients in whom AFD was excluded. The MSSI of patients with AFD was significantly higher than that of patients with other severe debilitating diseases. The MSSI indicated that, although more men than women had symptoms classified as severe, overall, the median total severity scores were not significantly different between male and female patients. One year of ERT with agalsidase alfa led, in all patients, to a significant (pu2003<u20030.001) reduction in MSSI score (by a median of nine points). This study has shown that the MSSI score may be a useful, specific measure for objectively assessing the severity of AFD and for monitoring ERT‐related treatment effects.

Long-term follow-up of endurance and safety outcomes during enzyme replacement therapy for mucopolysaccharidosis VI: Final results of three clinical studies of recombinant human N-acetylgalactosamine 4-sulfatase

UNLABELLEDnThe objective of this study was to evaluate the long-term clinical benefits and safety of recombinant human arylsulfatase B (rhASB) treatment of mucopolysaccharidosis type VI (MPS VI: Maroteaux-Lamy syndrome), a lysosomal storage disease. Fifty-six patients derived from 3 clinical studies were followed in open-label extension studies for a total period of 97-260 Weeks. All patients received weekly infusions of rhASB at 1 mg/kg. Efficacy was evaluated by (1) distance walked in a 12-minute walk test (12MWT) or 6-minute walk test (6MWT), (2) stairs climbed in the 3-minute stair climb (3MSC), and (3) reduction in urinary glycosaminoglycans (GAG). Safety was evaluated by compliance, adverse event (AE) reporting and adherence to treatment.nnnRESULTSnA significant reduction in urinary GAG (71-79%) was sustained. For the 12MWT, subjects in Phase 2 showed improvement of 255+/-191 m (mean+/-SD) at Week 144; those in Phase 3 Extension demonstrated improvement from study baseline of 183+/-26 m (mean+/- SE) in the rhASB/rhASB group at Week 96 and from treatment baseline (Week 24) of 117+/-25 m in the placebo/rhASB group. The Phase 1/2 6MWT and the 3MSC from Phase 2 and 3 also showed sustained improvements through the final study measurements. Compliance was 98% overall. Only 560 of 4121 reported AEs (14%) were related to treatment with only 10 of 560 (2%) described as severe.nnnCONCLUSIONnrhASB treatment up to 5 years results in sustained improvements in endurance and has an acceptable safety profile.

Cardiac manifestations of Anderson–Fabry disease in heterozygous females

OBJECTIVESnWe sought to define the prevalence of cardiac involvement in female patients with Anderson-Fabry disease (AFD).nnnBACKGROUNDnAnderson-Fabry disease is a rare inborn X-linked lysosomal storage disorder. Globotriaosylceramide (Gb(3)), the major substrate of the deficient alpha-galactosidase A enzyme, accumulates progressively in vulnerable cells, including the cardiovascular system. It has been believed that heterozygous females have less cardiac involvement than hemizygous males with AFD.nnnMETHODSnWe performed two-dimensional echocardiographic examinations of female patients heterozygous for AFD.nnnRESULTSnSince 1997, a total of 55 female patients (mean age, 39.6 years; range, 6.1 to 70.8 years) with proven AFD have been investigated prospectively at our hospital. Of these, 13 (23.6%) had normal left ventricular (LV) geometry and LV mass (LVM). Seven patients (12.7%) had concentric remodeling, 29 patients (52.7%) concentric LV hypertrophy (LVH), and 6 patients (10.9%) eccentric LVH (2 with subaortic pressure gradients). There was a strong correlation between age and the severity of LVH (r(2) = 0.905; p < 0.0001), and all patients older than 45 years had LVH. With increasing LVM, there was a significant age-independent decrease in systolic and diastolic LV function. Mild thickening of the aortic valve leaflets was present in 25.5% of patients, with the same percentage demonstrating mild thickening of the mitral valve leaflets. Mild mitral valve prolapse was documented in 10.9% of patients.nnnCONCLUSIONSnCardiac involvement, with LVH and structural valve abnormalities, is very common and worsens with age in females who are heterozygous for AFD, and they should therefore be considered candidates for enzyme replacement therapy.

Therapy for lysosomal storage disorders.

In the last years, much progress has been achieved in the field of lysosomal storage disorders. In the past, no specific treatment was available for the affected patients; management mainly consisted of supportive care and treatment of complications. As orphan drug regulations, however, encouraged development of drugs for these disorders by granting marketing exclusivity for 10 years and other commercial benefits, enzyme replacement therapy became available for lysosomal storage disorders, such as Gaucher disease, Fabry disease, mucopolysaccharidoses type I, II, and VI, and Pompe disease. This review will summarize the efficacy and clinical status of hematopoietic stem cell transplantation, enzyme replacement, and substrate deprivation therapy, and describe new therapeutic perspectives currently under preclinical investigations such as chaperone‐mediated therapy, stop‐codon read‐through therapy, and gene therapy.

Lysosomal alpha-galactosidase controls the generation of self lipid antigens for natural killer T cells.

Natural Killer T (NKT) cells are lipid-reactive, CD1d-restricted T lymphocytes important in infection, cancer, and autoimmunity. In addition to foreign antigens, NKT cells react with endogenous self lipids. However, in the face of stimulating self antigen, it remains unclear how overstimulation of NKT cells is avoided. We hypothesized that constantly degraded endogenous antigen only accumulates upon inhibition of alpha-galactosidase A (alpha-Gal-A) in lysosomes. Here, we show that alpha-Gal-A deficiency caused vigorous activation of NKT cells. Moreover, microbes induced inhibition of alpha-Gal-A activity in antigen-presenting cells. This temporary enzyme block depended on Toll-like receptor (TLR) signaling and ultimately triggered lysosomal lipid accumulation. Thus, we present TLR-dependent negative regulation of alpha-Gal-A as a mechanistic link between pathogen recognition and self lipid antigen induction for NKT cells.

Onset and progression of the Anderson–Fabry disease related cardiomyopathy

BACKGROUNDnCardiac involvement is responsible for substantial morbidity and mortality in Anderson-Fabry disease (AFD). We sought to document its onset and progression in a population of male and female AFD patients.nnnMETHODSnWe performed a cross sectional echocardiographic study of a cohort of 177 male and female AFD patients with subsequent longitudinal follow-up of 76 patients (38 males and 38 females; mean follow-up 4.5 years) who did not receive enzyme replacement therapy.nnnRESULTSnIn this population, aged 3.3 to 70.8 years, a strong correlation between age and left ventricular mass indexed (LVMi, g/m(2.7)) was found in both males and females (P<0.0001 for both). At the initial examination 48.6% of the male patients and 36.4% of the female patients were classified as having left ventricular hypertrophy (LVH). The cumulative prevalence of LVH peaked at age 40 years in males and 60 years in females. In patients with longitudinal follow-up, LVMi increased by 4.07+/-1.03 g/m(2.7) per year in males and by 2.31+/-0.81 g/m(2.7) in females (P<0.01, Wilcoxon rank sum). In patients with LVH at baseline, the median progression rate was 5.52 g/m(2.7) per year in males and by 1.80 g/m(2.7) in females (P=0.12).nnnCONCLUSIONnAFD is associated with high prevalence of LVH in both genders. However, the age of onset is delayed in females and progression rate slower.

Review of clinical presentation and diagnosis of mucopolysaccharidosis IVA.

Mucopolysaccharidosis type IVA (MPS IVA) was described in 1929 by Luis Morquio from Uruguay and James Brailsford from England, and was later found as an autosomal recessive lysosomal storage disease. MPS IVA is caused by mutations in the gene encoding the enzyme, N-acetylgalactosamine-6-sulfate sulfatase (GALNS). Reduced GALNS activity results in impaired catabolism of two glycosaminoglycans (GAGs), chondroitin-6-sulfate (C6S) and keratan sulfate (KS). Clinical presentations of MPS IVA reflect a spectrum of progression from a severe classical phenotype to a mild attenuated phenotype. More than 180 different mutations have been identified in the GALNS gene, which likely explains the phenotypic heterogeneity of the disorder. Accumulation of C6S and KS manifests predominantly as short stature and skeletal dysplasia (dysostosis multiplex), including atlantoaxial instability and cervical cord compression. However, abnormalities in the visual, auditory, cardiovascular, and respiratory systems can also affect individuals with MPS IVA. Diagnosis is typically based on clinical examination, skeletal radiographs, urinary GAG, and enzymatic activity of GALNS in blood cells or fibroblasts. Deficiency of GALNS activity is a common assessment for the laboratory diagnosis of MPS IVA; however, with recently increased availability, gene sequencing for MPS IVA is often used to confirm enzyme results. As multiple clinical presentations are observed, diagnosis of MPS IVA may require multi-system considerations. This review provides a history of defining MPS IVA and how the understanding of the disease manifestations has changed over time. A summary of the accumulated knowledge is presented, including information from the International Morquio Registry. The classical phenotype is contrasted with attenuated cases, which are now being recognized and diagnosed more frequently. Laboratory based diagnoses of MPS IVA are also discussed.

Cardiac manifestations of Anderson-Fabry disease in children and adolescents.

Aim: Fabry disease (Fabry) is a rare X‐linked disorder caused by a deficiency of the lysosomal enzyme α‐galactosidase A. The progressive accumulation of the major substrate, globotriaosylceramide, leads to renal dysfunction and hypertrophic cardiomyopathy, which are reported to become apparent in the third decade. This study was performed to determine if signs of cardiac manifestations of Fabry are seen in younger Fabry patients.

Fabry disease in children and the effects of enzyme replacement treatment

Fabry disease is a rare, X-linked inborn error of glycosphingolipid catabolism caused by a deficiency in the activity of the lysosomal enzyme, α-galactosidase A. In affected patients, the enzyme substrate, globotriaosylceramide (Gb3), accumulates in cells of various tissues and organs. Lysosomal accumulation of Gb3 begins in utero, and signs and symptoms of Fabry disease emerge in childhood and adolescence. The earliest presenting symptoms are typically neuropathic pain and gastrointestinal problems, which can have a substantial impact on health-related quality of life. Life-threatening major organ involvement is rare in young patients, but signs of kidney dysfunction (e.g., proteinuria), left ventricular hypertrophy, and stroke have been reported in children. There are two enzyme preparations for therapy: agalsidase alfa and beta. In two clinical trials of enzyme replacement therapy (ERT) with agalsidase alfa, including 37 children, boys demonstrated reductions in plasma Gb3 levels, and both boys and girls reported reductions in neuropathic pain and in the use of neuropathic pain medications. Heart rate variability, which is reduced in boys with Fabry disease, was statistically significantly improved with 6xa0months of agalsidase alfa treatment. In a single clinical study of agalsidase beta in children (nu2009=16), skin Gb3 deposits and plasma Gb3 levels were reduced in boys. Differences exist in the administration and the safety profile of these two enzyme formulations. Follow-up of these cohorts and additional studies will be necessary to fully evaluate long-term efficacy of ERT in children with Fabry disease.