The ultrastructural characteristics of eccrine sweat glands in a Fabry disease patient with hypohidrosis

Molecular Pathogenesis of Central and Peripheral Nervous System Complications in Anderson-Fabry Disease

Fabry disease (FD) is a recessive monogenic disease linked to chromosome X due to more than two hundred mutations in the alfa-galactosidase A (GLA) gene. Modifications of the GLA gene may cause the progressive accumulation of globotriaosylceramide (Gb3) and its deacylated form, globotriasylsphingosine (lyso-Gb3), in lysosomes of several types of cells of the heart, kidneys, skin, eyes, peripheral and central nervous system (not clearly and fully demonstrated), and gut with different and pleiotropic clinical symptoms. Among the main symptoms are acroparesthesias and pain crisis (involving the peripheral nervous system), hypohidrosis, abdominal pain, gut motility abnormalities (involving the autonomic system), and finally, cerebrovascular ischemic events due to macrovascular involvement (TIA and stroke) and lacunar strokes and white matter abnormalities due to a small vessel disease (SVS). Gb3 lysosomal accumulation causes cytoplasmatic disruption and subsequent cell death. Additional consequences of Gb3 deposits are inflammatory processes, abnormalities of leukocyte function, and impaired trafficking of some types of immune cells, including lymphocytes, monocytes, CD8+ cells, B cells, and dendritic cells. The involvement of inflammation in AFD pathogenesis conflicts with the reported poor correlation between CRP levels as an inflammation marker and clinical scores such as the Mainz Severity Score Index (MSSI). Also, some authors have suggested an autoimmune reaction is involved in the disease's pathogenetic mechanism after the α-galactosidase A deficiency. Some studies have reported a high degree of neuronal apoptosis inhibiting protein as a critical anti-apoptotic mediator in children with Fabry disease compared to healthy controls. Notably, this apoptotic upregulation did not change after treatment with enzymatic replacement therapy (ERT), with a further upregulation of the apoptosis-inducing factor after ERT started. Gb3-accumulation has been reported to increase the degree of oxidative stress indexes and the production of reactive oxygen species (ROS). Lipids and proteins have been reported as oxidized and not functioning. Thus, neurological complications are linked to different pathogenetic molecular mechanisms. Progressive accumulation of Gb3 represents a possible pathogenetic event of peripheral nerve involvement. In contrast, central nervous system participation in the clinical setting of cerebrovascular ischemic events seems to be due to the epitheliopathy of Anderson-Fabry disease with lacunar lesions and white matter hyperintensities (WMHs). In this review manuscript, we revised molecular mechanisms of peripheral and central neurological complications of Anderson-Fabry Disease. The management of Fabry disease may be improved by the identification of biomarkers that reflect the clinical course, severity, and progression of the disease. Intensive research on biomarkers has been conducted over the years to detect novel markers that may potentially be used in clinical practice as a screening tool, in the context of the diagnostic process and as an indicator of response to treatment. Recent proteomic or metabolomic studies are in progress, investigating plasma proteome profiles in Fabry patients: these assessments may be useful to characterize the molecular pathology of the disease, improve the diagnostic process, and monitor the response to treatment.

Morphological Hallmarks of Classical Fabry Disease: An Ultrastructural Study in a Large Spanish Family

Fabry disease (FD) is a rare lysosomal disorder caused by α-galactosidase A deficiency, and it leads to the systemic deposition of globotriasylceramide. Demonstrations of the storage material in biopsies support this diagnosis. We report a histological and ultrastructural study of biopsies that were performed on 11 individuals from a family with the variant p.Gln279Arg in GLA, which is associated with the classical phenotype of Fabry disease. Intralysosomal deposits were found in all biopsies, corresponding to the skin, kidney, and endomyocardium in both sexes and at different ages. In nine of the skin biopsies, deposits were analysed by immunofluorescence and quantified at the ultrastructural level. Then, the findings were compared according to sex, genotype, and treatment. The quantification of the deposits in the skin biopsies revealed a broader involvement in men than in women. A significant clearance of the deposits was observed in one case after treatment. Tissue involvement was remarkable at diagnosis in all individuals. The findings from the skin biopsies were demonstrative of classic FD, thus supporting the diagnosis; repeated biopsy analyses suggested the benefit of early treatment.

The evolution of the initial manifestations and renal involvement of chinese patients with classical and late-onset Fabry disease at different sexes and ages

BACKGROUND

Fabry disease is a rare hereditary disease involving multiple organs, and there are few reports on how the initial manifestations and renal involvement of these patients with classical and late-onset phenotype evolve with sexes and ages. To improve clinicians' understanding of Fabry disease and avoid misdiagnoses by discussing the initial manifestations, first medical specialties visited and renal involvement development in patients.

METHODS

This study collected relevant data from 311 Chinese Fabry disease patients (200 males, 111 females) and descriptive statistical analysis was used to analyze the evolution of the initial manifestations and renal involvement of patients with classical and late-onset phenotype at different sexes and ages.

RESULTS

Regarding the age at manifestation onset, age at the first medical specialty visited and age at the diagnosis of Fabry disease, males were earlier than females, and males with classical phenotype were earlier than males with late-onset and females with classical phenotype. In both male and female patients, the initial manifestations of classical patients were mainly acroparesthesia, and the first medical specialty visited were mainly pediatrics and neurology. The initial manifestations of late-onset patients were mainly renal and cardiovascular involvement, and the first medical specialty visited were mainly nephrology and cardiology. In classical patients, both male and female, the initial manifestations of the preschool and the juvenile groups were mainly acroparesthesia, and the frequency of renal and cardiovascular involvement in the young group was higher than that in the preschool and juvenile groups. There was no obvious renal involvement in the preschool group, renal involvement was most common in the young group and the middle-aged and elderly group. Proteinuria can appear in classical male patients as early as approximately 20 years, and renal insufficiency can occur at approximately 25 years. With age, over 50% of classical male patients can develop varying degrees of proteinuria at the age of 25 and renal insufficiency at the age of 40. 15.94% of the patients progressed to dialysis or kidney transplantation, mainly classical males.

CONCLUSIONS

The initial manifestation of Fabry disease is affected by sex, age and classical/late-onset phenotype. The initial manifestations were mainly acroparesthesia and the frequency and degree of renal involvement increased gradually with aging in classical male patients.

Beneficial screening of Fabry disease in patients with hypohidrosis

Fabry disease (FD), which is a lysosomal storage disease resulting from a deficiency of α-galactosidase A, leads to the accumulation of globotriaosylceramide in various tissues and multiorgan impairment. Early diagnosis is important to improve long-term prognosis. Early clinical manifestations of FD include neuropathic pain, vascular skin lesions, and sweating abnormalities. Hypohidorosis is one of the clinical findings in the early stage of FD. However, there have been no studies on prospective screening of FD in patients with definitive diagnosis of hypohidrosis. We examined α-galactosidase A activity in white blood cells in 17 (one female and 16 male) patients with generalized hypohidorosis. Among 17 patients, one male patient (approximately 5.8%) had significantly reduced α-galactosidase A activity. He presented with a history of hypohidrosis with heat intolerance and neuropathic tingling pain in a warm environment from 6 years ago. He had a few angiokeratoma on the trunk and extremities. Ultrastructural examination of skin biopsy from the angiokeratoma revealed lamellar inclusions in endothelial cells. Kidney biopsy revealed swollen podocytes and Gb3 deposition in the glomerulus, and urinalysis revealed mulberry bodies. He was finally diagnosed with FD and started on enzyme replacement therapy with agalsidase alpha in the early stage. In addition, his family screening led to find the patients of four additional FD. Screening for FD in patients with hypohidrosis may lead to efficient early detection of FD.

Anderson-Fabry Disease: From Endothelial Dysfunction to Emerging Therapies

The Anderson–Fabry disease is a rare, X-linked, multisystemic, progressive lysosomal storage disease caused by α-galactosidase A total or partial deficiency. The resulting syndrome is mainly characterized by early-onset autonomic neuropathy and life-threatening multiorgan involvement, including renal insufficiency, heart disease, and early stroke. The enzyme deficiency leads to tissue accumulation of the glycosphingolipid globotriaosylceramide and its analogues, but the mechanisms linking such accumulation to organ damage are only partially understood. In contrast, enzyme replacement and chaperone therapies are already fully available to patients and allow substantial amelioration of quality and quantity of life. Substrate reduction, messenger ribonucleic acid (mRNA)-based, and gene therapies are also on the horizon. In this review, the clinical scenario and molecular aspects of Anderson–Fabry disease are described, along with updates on disease mechanisms and emerging therapies.

Skin Globotriaosylceramide 3 Load Is Increased in Men with Advanced Fabry Disease

BACKGROUND

The X-chromosomally linked life-limiting Fabry disease (FD) is associated with deposits of the sphingolipid globotriaosylceramide 3 (Gb3) in various tissues. Skin is easily accessible and may be used as an additional diagnostic and follow-up medium. Our aims were to visualize skin Gb3 deposits in FD patients applying immunofluorescence and to determine if cutaneous Gb3 load correlates with disease severity.

METHODS

At our Fabry Center for Interdisciplinary Therapy we enrolled 84 patients with FD and 27 healthy controls. All subjects underwent 5-mm skin punch biopsy at the lateral lower leg and the back. Skin samples were processed for immunohistochemistry using antibodies against CD77 (i.e. Gb3). Cutaneous Gb3 deposition was quantified in a blinded manner and correlated to clinical data.

RESULTS

We found that Gb3 load was higher in distal skin of male FD patients compared to healthy controls (p<0.05). Men (p<0.01) and women (p<0.05) with a classic FD phenotype had higher distal skin Gb3 load than healthy controls. Men with advanced disease as reflected by impaired renal function, and men and women with small fiber neuropathy had more Gb3 deposits in distal skin samples than males with normal renal function (p<0.05) and without small fiber neuropathy. Gb3 deposits were not different between patients with and without enzyme replacement therapy.

CONCLUSIONS

Immunofluorescence on minimally invasive skin punch biopsies may be useful as a tool for assessment and follow-up in FD patients.

Sudoscan as a noninvasive tool to assess sudomotor dysfunction in patients with Fabry disease: results from a case-control study

Hypohidrosis is a frequent and early symptom in patients with Fabry disease. Studies have reported improved sweating in patients treated with enzyme-replacement therapy. A new method, Sudoscan, has been developed that is noninvasive, is quantitative, and can quickly evaluate sweat gland function. It is based on the electrochemical reaction between sweat chlorides and stainless-steel electrodes in contact with the palms and soles. The aim of our study was to evaluate the Sudoscan as a tool to assess sudomotor dysfunction in patients with Fabry disease. Consecutive patients were prospectively recruited who had a diagnosis of Fabry disease, which had been confirmed genetically and/or by measurement of α-galactosidase activity in leukocytes. Healthy controls, matched (1:1) for age and sex, were also enrolled. Test results were expressed immediately as electrochemical skin conductance (ESC, µS) for hands and feet. Sudomotor dysfunction was considered absent, moderate, or severe if the ESC measured on the feet was >60 µS, between 60 and 40 µS, or <40 µS, respectively. Among the 18 patients, 11 had hypohidrosis or anhidrosis. Hand and feet ESCs were significantly lower in patients compared to their controls (P=0.0015 and P=0.0047, respectively). Among patients, 8/18 (44.5%) had a sudomotor dysfunction, moderate in three and severe in five cases. Hand and feet ESCs were significantly lower in those with hypohidrosis/anhidrosis compared to those without (P=0.0014 and P=0.0056, respectively). This study showed that Sudoscan provided a quick, noninvasive, and quantitative measurement of sudomotor function in Fabry disease patients.

Fabry disease

Fabry disease results from deficient activity of the enzyme α-galactosidase A and progressive lysosomal deposition of globotriaosylceramide (GL-3) in cells throughout the body. The main neurological presentations of Fabry disease patients are painful neuropathy, hypohidrosis, and stroke. Fabry neuropathy is characterized as a length-dependent peripheral neuropathy affecting mainly the small myelinated (Aδ) fibers and unmyelinated (C) fibers. Enzyme replacement therapy (ERT) has been shown to have some positive effects on the reduction of neuropathic pain, the improvement of detection threshold for thermal sensation, and sweat function. On the contrary, the effect of ERT on the central nervous system has not been established. Early initiation of ERT before irreversible organ failure is extremely important, and alternative therapeutic approaches are currently being explored. Heterozygotes suffer from peripheral neuropathy at a higher rate than previously shown, significant multisystemic disease, and severely decreased quality of life. As well as being carriers, heterozygotes also display symptoms of Fabry disease, and should be carefully monitored and given adequate therapy.

Fabry disease

PURPOSE OF REVIEW

This review discusses the literature on Fabry disease mainly in the domain of neurology with special attention to recent advancement.

RECENT FINDINGS

Fabry neuropathy is known as a length-dependent peripheral neuropathy affecting mainly the small myelinated (Aδ) fibers and unmyelinated (C) fibers. Recently, concerning heterozygotes, it seems that they suffer from peripheral neuropathy at a higher rate than previously shown, significant multisystemic disease, and severely decreased quality of life. The existence of an atypical variant of Fabry disease with late-onset cerebrovascular disease (cerebrovascular variant) is now suggested, like the cardiac and renal variants of Fabry disease. Although enzyme replacement therapy (ERT) has been shown to have some positive effects on reduction of neuropathic pain, the improvement of detection threshold for thermal sensation and sweat function, the effect of ERT on the central nervous system has not been established. Gene replacement therapy, chemical chaperone therapy, and ERT using modified α-N-acetylgalactosaminidase are in progress, and induced pluripotent stem cells were generated from mouse models of Fabry disease.

SUMMARY

Heterozygotes should be carefully monitored for precise estimation and adequate therapy. Early initiation of ERT before irreversible organ failure is most important, and alternative therapeutic approaches are currently being explored.

Early diagnosis of peripheral nervous system involvement in Fabry disease and treatment of neuropathic pain: the report of an expert panel

Background

Fabry disease is an inherited metabolic disorder characterized by progressive lysosomal accumulation of lipids in a variety of cell types, including neural cells. Small, unmyelinated nerve fibers are particularly affected and small fiber peripheral neuropathy often clinically manifests at young age. Peripheral pain can be chronic and/or occur as provoked attacks of excruciating pain. Manifestations of dysfunction of small autonomic fibers may include, among others, impaired sweating, gastrointestinal dysmotility, and abnormal pain perception. Patients with Fabry disease often remain undiagnosed until severe complications involving the kidney, heart, peripheral nerves and/or brain have arisen.

Methods

An international expert panel convened with the goal to provide guidance to clinicians who may encounter unrecognized patients with Fabry disease on how to diagnose these patients early using simple diagnostic tests. A further aim was to offer recommendations to control neuropathic pain.

Results

We describe the neuropathy in Fabry disease, focusing on peripheral small fiber dysfunction - the hallmark of early neurologic involvement in this disorder. The clinical course of peripheral pain is summarized, and the importance of medical history-taking, including family history, is highlighted. A thorough physical examination (e.g., angiokeratoma, corneal opacities) and simple non-invasive sensory perception tests could provide clues to the diagnosis of Fabry disease. Reported early clinical benefits of enzyme replacement therapy include reduction of neuropathic pain, and adequate management of residual pain to a tolerable and functional level can substantially improve the quality of life for patients.

Conclusions

Our recommendations can assist in diagnosing Fabry small fiber neuropathy early, and offer clinicians guidance in controlling peripheral pain. This is particularly important since management of pain in young patients with Fabry disease appears to be inadequate.

Autonomic skin responses in females with Fabry disease

Fabry disease is a genetic lysosomal disorder with dysfunction of the lysosomal enzyme alpha-galactosidase A causing accumulation of glycolipids in multiple organs including the nervous system and with neuropathy as a prominent manifestation. Neurological symptoms include pain and autonomic dysfunction. This study examined peripheral autonomic nerve function in 19 female patients with Fabry disease and 19 sex and age-matched controls by measuring (1) sweat production following acetylcholine challenge; (2) the sympathetically mediated vasoconstrictor responses to inspiratory gasp, stress, and the cold pressor test; and (3) cutaneous blood flow following capsaicin. The vasoconstrictor response to inspiratory gasp was increased in Fabry patients compared to controls (p = 0.03), while the response to cold and mental stress did not change. Female patients with Fabry disease had a reduced sweat response to iontophoresis of acetylcholine (p = 0.04) and a smaller capsaicin-induced flare compared to controls. These findings suggest that female patients both have an impaired C-fiber function and local abnormalities in blood vessels and sweat glands.

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, alpha-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 6 months of agalsidase alfa treatment. In a single clinical study of agalsidase beta in children (n =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.

Doença de Fabry

A doença de Fabry é enfermidade de armazenamento lisossômico rara, ligada ao cromossomo-X, causada pela deficiência parcial ou completa da enzima alfagalactosidase A. O defeito resulta no acúmulo de globotriaosilceramida no endotélio vascular e tecidos viscerais, sendo a pele, o coração, os rins e o sistema nervoso central os mais afetados. As autoras realizam revisão da literatura relacionada a essa afecção e ressaltam que o reconhecimento precoce dos angioqueratomas e da hipoidrose constitui sinal-chave no diagnóstico dessa doença grave. Destacam também a necessidade de esses doentes serem avaliados por equipe multidisciplinar.

Fabry disease-often seen, rarely diagnosed

BACKGROUND

Data obtained from screened newborns and from persons at known risk for Fabry disease suggest that this condition is much more common in Germany than previously assumed. Its clinical manifestations are very diverse, and its differential diagnosis is correspondingly broad. Thus, there is often a delay before the diagnosis of Fabry disease is established.

METHODS

Selective literature search with special attention to studies of large groups of patients with respect to clinical manifestations, diagnostic evaluation, and treatment.

RESULTS

The number of patients carrying the diagnosis of Fabry disease in Germany lies far below what would be expected from published prevalence figures from other countries. Angiokeratoma, acroparesthesia, hypertrophic cardiomyopathy, impaired sweating and corneal opacification (cornea verticillata) are typical manifestations of Fabry disease; many patients also have other, nonspecific complaints, such as gastrointestinal disturbances. It has been clearly shown that women can manifest the entire range of clinical manifestations. Studies involving large groups of patients have improved our understanding of hearing impairment and tinnitus in Fabry disease. Therapeutic trials are currently in progress to determine whether enzyme substitution can delay the occurrence of life-threatening sequelae such as progressive renal failure and cerebrovascular events.

CONCLUSIONS

Fabry disease is still underdiagnosed. The average delay from the onset of symptoms to diagnosis is more than a decade. Treatment with human alpha-galactosidase A produced with genetic technology can improve most of the disease's manifestations.

Wilson protein expression, copper excretion and sweat production in sweat glands of Wilson disease patients and controls

Background

In Wilson disease, copper is not sufficiently excreted into bile due to the absence or malfunction of the Wilson protein copper ATPase in the excretory pathway of hepatocytes. Copper is found in sweat. It is unknown if the Wilson protein plays a role in copper excretion into sweat. It is the aim of this study to investigate Wilson protein expression in sweat glands and analysing its effects on copper excretion into sweat in controls and patients with Wilson disease.

Methods

Immunofluorescent analysis of the Wilson protein in skin samples from normal rat, LEC rat and human skin biopsies were performed. Pilocarpin-induced sweat gland stimulation by iontophoretic transfer adapted from the methods used for cystic fibrosis sweat test was used for sweat induction. Sweat volume, sweat copper concentration, serum ceruloplasmin and serum copper were analysed in 28 Wilson patients and 21 controls.

Results

The Wilson protein is expressed in human and rat sweat gland epithelia. Copper concentration in sweat is not significantly different between controls and Wilson patients. Wilson patients produce significantly smaller volumes of sweat compared to controls. Sweat production is partially reversible in Wilson patients under medical treatment for Wilson disease or after liver transplantation

Conclusion

Wilson patients show a reduced sweat production with unaltered sweat copper concentration. The Wilson protein might play an important role in physiological sweat production.

Early therapeutic intervention in females with Fabry disease?

Anderson-Fabry disease is an X-linked lysosomal storage disorder resulting from deficiency of alpha-galactosidase A. The subsequent accumulation of globotriaosylceramide (Gb3) in cells and tissues of the body has multisystemic effects and significantly impacts upon quality of life and survival of individuals with this condition. In general, Anderson-Fabry disease is more severe in male patients; however, despite X-linkage, females may develop severe signs and symptoms of the disease, although there is considerable phenotypic heterogeneity, which correlates most closely with age. Histological analyses of biopsies have shown evidence of Gb3 storage in the kidney and heart in female patients. Gb3 levels are also elevated in the urine of females, although plasma Gb3 levels are not reliably elevated. The efficacy of enzyme replacement therapy (ERT) with recombinant human alpha-galactosidase A has been demonstrated in females in a clinical trial and in observational studies, including those using data from outcome surveys. Benefits include a reduction in left ventricular mass, stabilization of renal function and improvements in pain and quality of life.

CONCLUSION

If early intervention with ERT in females is to be advocated, it is necessary to demonstrate not only that females with Anderson-Fabry disease have clinical and biochemical features of alpha-galactosidase A deficiency and respond to ERT, but also that early intervention prevents the onset of the later manifestations of the disorder. Any strategy for early therapy should also balance future advantages against any impact on quality of life.

Neurological manifestations in Fabry's disease

Fabry's disease is an X-linked lysosomal storage disorder caused by a defect in the gene that encodes the lysosomal enzyme alpha-galactosidase A. Symptoms arise because of accumulation of globotriaosylceramide in multiple organs, resulting in severely reduced quality of life and premature death. Neurological symptoms, such as burning sensations (occasionally accompanied by acroparesthesia) and stroke, are among the first to appear, and occur in both male and female patients. A delay in establishing the diagnosis of Fabry's disease can cause unnecessary problems, especially now that enzyme replacement treatment is available to prevent irreversible organ damage. Females with Fabry's disease who present with pain have often been ignored and misdiagnosed because of the disorder's X-linked inheritance. This Review will stress the importance of recognizing neurological symptoms for the diagnosis of Fabry's disease. The possible pathophysiological background will also be discussed.

Hyperhidrosis: a new and often early symptom in Fabry disease. International experience and data from the Fabry Outcome Survey

Hypohidrosis is a classic feature of Fabry disease; in contrast, hyperhidrosis has only been rarely described. The aim of the study is to characterise the baseline descriptive data on hyperhidrosis (frequency, age at onset, sex ratio and outcome with and without enzyme replacement therapy) in hemizygous male and heterozygous female patients with Fabry disease. We describe case histories of five patients with Fabry disease and hyperhidrosis seen at three different centres. We have also analysed a cohort of 21 paediatric patients in the UK and a large European cohort of patients enrolled in the Fabry Outcome Survey (FOS). Five patients (three female, two male) with hyperhidrosis were originally identified, although each had additional symptoms related to Fabry disease. The age at onset of hyperhidrosis was less than 18 years in four cases. In the cohort of 21 paediatric patients (12 female, nine male), one female had hyperhidrosis; the age at onset of this symptom was 11 years. In the FOS cohort, 66 of 714 patients with Fabry disease had hyperhidrosis (44 of 369 females, 11.9%; 22 of 345 males, 6.4%). The female predominance was observed in seven of nine countries from which data were analysed. Hyperhidrosis is an increasingly recognised feature of the Fabry disease phenotype. It is more prevalent in females than in males and often appears in childhood or adolescence. The efficacy of enzyme replacement therapy on this recently recognised symptom should be assessed.

Fabry disease: Guidelines for the evaluation and management of multi-organ system involvement

Fabry disease is an X-linked metabolic storage disorder due to the deficiency of lysosomal alpha-galactosidase A, and the subsequent accumulation of glycosphingolipids, primarily globotriaosylceramide, throughout the body. Males with classical Fabry disease develop early symptoms including pain and hypohidrosis by the second decade of life reflecting disease progression in the peripheral and autonomic nervous systems. An insidious cascade of disease processes ultimately results in severe renal, cardiac, and central nervous system complications in adulthood. The late complications are the main cause of late morbidity, as well as premature mortality. Disease presentation in female heterozygotes may be as severe as in males although women may also remain asymptomatic. The recent introduction of enzyme replacement therapy to address the underlying pathophysiology of Fabry disease has focused attention on the need for comprehensive, multidisciplinary evaluation and management of the multi-organ system involvement. In anticipation of evidence-based recommendations, an international panel of physicians with expertise in Fabry disease has proposed guidelines for the recognition, evaluation, and surveillance of disease-associated morbidities, as well as therapeutic strategies, including enzyme replacement and other adjunctive therapies, to optimize patient outcomes.

Monitoring perspiration from palms of hypohidrosis patients with a stopped-flow conductometric mini-system

BACKGROUND

Sensitive and real-time methods are required to characterize the symptoms and resolve the complicated pathology of hypohidrosis.

METHOD

We constructed a conductometric humidity sensor and a stopped-flow manifold with suitable dynamic range for monitoring impaired perspiration. The mini-sensor was coated with a water-absorbing polymer of poly-(2-acrylamido-2-methylpropane sulfonate).

RESULTS

Perspiration from palms of normal individuals and hypohidrosis patients were monitored and compared. Tangent slopes of the sensorograms were capable of discriminating hypohidrosis patients from normal individuals.

CONCLUSION

The conductometric min-sensor and the stopped-flow manifold were proven to be useful as a diagnostic tool for hypohidrosis.

Monitoring the 3-year efficacy of enzyme replacement therapy in fabry disease by repeated skin biopsies

The earliest clinical signs of Fabry disease often manifest as dermatologic disturbances such as angiokeratomata, hypohidrosis, acroparesthesias, and impaired thermal and vibration detection. These disturbances are caused by cellular globotriaosylceramide accumulation in the skin due to deficient lysosomal alpha-galactosidase A activity. In this histologic study, we analyzed pre- and post-treatment dermatologic biopsies from 58 Fabry patients enrolled in a 5 mo, Phase 3 double-blind, randomized, placebo-controlled trial followed by a 30 mo open label extension study of recombinant human alpha-galactosidase A (r-halphaGalA), administered i.v. at 1 mg per kg every 2 wk. Baseline evaluations revealed globotriaosylceramide in multiple dermal cell types (vascular endothelial cells, vascular smooth muscle cells, perineurium). Five months of r-halphaGalA treatment in the Phase 3 trial resulted in complete clearance of globotriaosylceramide from the superficial capillary endothelium in all treatment patients and in only 1 (3%) placebo patient (p<0.001). The placebo group achieved similar results after 6 mo of r-halphaGalA in the open label trial. The capillary endothelium remained free of globotriaosylceramide for up to 30 mo into the extension study among 39 of 40 (98%) patients who underwent biopsies. Globotriaosylceramide clearance from deep vascular endothelial cells was similarly robust. Vascular smooth muscle cells and perineurium demonstrated moderate clearance. These findings suggest that long-term treatment with r-halphaGalA may halt the progression of pathology and prevent the dermatologic disturbances in Fabry patients, and that periodic dermal biopsies can serve as a reliable monitor of sustained efficacy.

Enzyme replacement therapy improves peripheral nerve and sweat function in Fabry disease

Fabry disease is an X-linked disorder caused by a deficiency of lysosomal alpha-galactosidase A resulting in accumulation of alpha-D-galatosyl conjugated glycosphingolipids. Clinical manifestations include a small-fiber neuropathy associated with debilitating pain and hypohidrosis. We report the effect of a 3-year open-label extension of a previously reported 6-month placebo-controlled enzyme replacement therapy (ERT) trial in which 26 hemizygous patients with Fabry disease received 0.2 mg/kg of alpha-galactosidase A every 2 weeks. The effect of ERT on neuropathic pain scores while off pain medications, quantitative sensory testing, quantitative sudomotor axon reflex test (QSART), and thermoregulatory sweat test (TST) is reported. In the patients who crossed-over from placebo to ERT (n = 10), mean pain-at-its-worst scores on a 0-10 scale decreased (from 6.9 to 4.5). There was a significant reduction in the threshold for cold and warm sensation in the foot. At the 3-year time-point, pre-ERT sweat excretion in 17 Fabry patients was 0.24 +/- 0.33 microl/mm(2) vs. 1.05 +/- 0.81 in concurrent controls (n = 38). Sweat function improved 24-72 h post-enzyme infusion (0.57 +/- 0.71 microl/mm(2)) and normalized in four anhidrotic patients. TST confirmed the QSART results. We conclude that prolonged ERT in Fabry disease leads to a modest but significant improvement in the clinical manifestations of the small-fiber neuropathy associated with this disorder. QSART may be useful to further optimize the dose and frequency of ERT.

The early clinical phenotype of Fabry disease: a study on 35 European children and adolescents

Fabry disease (FD) is a debilitating progressive multisystem X-linked lysosomal storage disorder. It was generally believed that the disease affects only adult males. Through systematic pedigree analysis, we identified 35 paediatric FD patients (age 1 to 21 years, mean 12.6 years) in 25 families. Predominant signs in this cohort were: acroparesthesia, hypohidrosis, and cornea verticillata. Neurological and psychological changes, such as tinnitus, recurrent vertigo, headache, diminished level of activity, fatigue, and depression were often observed. Angiokeratoma and gastrointestinal symptoms were frequent. Some patients also showed cardiac abnormalities. Six children and adolescents (three males and three females) over 14 years of age had renal involvement (all with proteinuria, one male had a decreased creatinine clearance of 62 ml/min). No males, but three females (1.5, 4 and 9 years of age), were free of signs and symptoms. Males (n=15, age 1 to 21 years, mean 12.4 years) and females (n=20, age 1.5 to 20 years, mean 12.7 years) showed comparable disease severity. However, the clinical courses demonstrated a wide intra- and interfamilial variability and tended to be more heterogeneous in the girls. Female patients are frequently affected at an early age, not much differently than males. They should be carefully examined because most carriers are symptomatic.

CONCLUSION

Fabry disease usually becomes clinically manifest in childhood. Renal involvement can begin in adolescence. The diagnosis is made following a high level of suspicion or systematic pedigree analysis. It is crucial for paediatric Fabry disease patients to have early access to optimal supportive symptomatic management. Enzyme replacement therapy has shown promising effectiveness in adults. Considering its widespread therapeutic and potential preventive benefits, enzyme replacement therapy should be initiated at an early stage, prior to the onset of irreversible complications.

Fabry disease: recognition and management of cutaneous manifestations

Fabry disease (angiokeratoma corporis diffusum universale) is a rare, X chromosome-linked lysosomal storage disease. The deficient enzyme, alpha-galactosidase A (alpha-gal A), is responsible for the accumulation of neutral glycosphingolipids within vascular endothelial lysosomes of various organs, including skin, kidneys, heart, and brain. The disease manifests primarily in affected hemizygous men and to some extent in heterozygous women ('carriers'). The diagnosis of Fabry disease is made in hemizygous males after the detection of the presence of angiokeratomas, irregularities in sweating, edema, scant body hair, painful sensations, and of cardiovascular, gastrointestinal, renal, ophthalmologic, phlebologic, and respiratory involvement. A deficiency of alpha-gal A in serum, leukocytes, tears, tissue specimens, or cultured skin fibroblasts further supports the diagnosis in male patients. Since heterozygous women show angiokeratomas in only about 30% of cases and may have alpha-gal A levels within normal range, genetic analysis is recommended. Current treatment of angiokeratomas of Fabry disease is based mainly on the use of laser systems, including variable pulse width 532nm Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) laser, 578nm copper vapor laser, and flashlamp-pumped dye laser. When cutaneous and mucous glands are affected, restrictions may be required with regard to the time spent in a warm climate and the amount time spent working or on sporting activities, and may necessitate the use of topical and systemic antiperspirant agents, and topical application of artificial lacrimal fluid and saliva, respectively. For the future, new treatment modalities, including enzyme replacement therapy, substrate deprivation strategies, and gene therapy offer extraordinary options for the cutaneous and visceral lesions in patients with Fabry disease.

Fabry disease--a metabolic disorder with a challenge for endocrinologists?

OBJECTIVE

To revisit Fabry disease, a rare X-linked metabolic glycosphingolipid storage disease caused by a deficiency of the lysosomal enzyme alpha-galactosidase A (alpha-gal A).

METHOD

Summary of the existing knowledge of Fabry disease including the clinical feature of Fabry disease and the recent breakthrough in the treatment of Fabry patients with the development of recombinant human alpha-gal A.

CONCLUSION

The diffuse organ manifestations of Fabry disease resemble medical endocrinological diseases, and medical endocrinology might be an appropriate speciality to manage the treatment in collaboration with other specialists and clinical geneticists.

Pathophysiology and assessment of neuropathic pain in Fabry disease

Severe neuropathic pain and hypohidrosis are important symptoms of Fabry disease, particularly in the first three decades of life. The pain is associated with a length-dependent small-fibre neuropathy that also causes a selective deficiency of cold perception. Cold exposure often accentuates the pain and worsens thermal perception. The hypohidrosis leads to poor exercise and heat tolerance. The mechanisms by which alpha-galactosidase A deficiency causes these physiological abnormalities are poorly understood. The stored glycolipid (globotriaosylceramide) may interfere with the function of cellular membrane proteins, such as ion channels, or may lead to cytotoxicity. The characteristic neuropathic pain can be symptomatically treated with various types of anticonvulsant drugs, such as carbamazepine. Improvement in neuropathic pain as a primary outcome measure has been useful in demonstrating that enzyme replacement therapy is effective in improving pain-related quality of life in Fabry disease.

CONCLUSIONS

The dysfunction of the peripheral nervous system is easily assessable and more readily reversible with specific therapy than the destructive processes that occur in organs such as the kidney. In future, therefore, it is likely that neuropathic pain, quantitative sensory testing and hypohidrosis will serve as clinical outcome measures for studies of specific and effective therapies for Fabry disease.

Neuropathic pain in Anderson-Fabry disease: pathology and therapeutic options

An inherited deficiency of the enzyme alpha-galactosidase A is manifest clinically as Anderson-Fabry disease. Most affected patients present with severe peripheral pain in childhood or early adult life, and frequently progress to multi-organ failure by the 4th or 5th decades. The present review examines the probable mechanisms that contribute to pain in these patients, and outlines some of the treatment options that are currently used. The successful outcome of the first two trials of enzyme replacement therapy suggest that this disease might be amenable in the future to gene therapy.