Neurological manifestations in Fabry's disease

Clinical significance of small nerve fiber involvement in the early diagnosis and treatment of patients with Fabry disease

INTRODUCTION

Peripheral nervous system is early involved in Fabry disease (FD) and preferentially the small nerve fibers, causing the characteristic neuropathic pain crises usually beginning in childhood. Early detection of this likely underdiagnosed disease is an important approach because causal therapies are available.

METHODS

We conducted a case-series study to investigate the small nerve fiber involvement in FD and its contribution to the diagnosis of the disease but also to the timely effective therapy administration. We used specific structured scales of symptoms and signs to detect peripheral neuropathy, as well as suitable functional and structural tests to diagnose the small fiber neuropathy (SFN).

RESULTS

Twenty-seven consecutive patients (14 men, mean age 44.62 ± 10.70 years) with suspected FD were included in this study. Most of the patients presented symptoms of small nerve fiber involvement, which were accompanied by abnormal test results, fulfilling the criteria for SFN. The detection of SFN in our patients allowed the completion of the FD diagnostic criteria and thus the initiation of therapy. In five patients the SFN diagnosis determined the administration of therapy, whereas in two others it might be considered.

CONCLUSION

Our results further suggest the importance of early diagnosis of peripheral neuropathy, especially of small nerve fiber involvement, in patients with suspected FD as it contributes crucially not only to the diagnosis but also to the timely effective initiation of FD therapy.

Management of pain in Fabry disease in the UK clinical setting: consensus findings from an expert Delphi panel

BACKGROUND

Fabry disease is a rare, X-linked inherited lysosomal storage disorder, that manifests as a heterogeneous disease with renal, cardiac and nervous system involvement. The most common pain experienced by people with Fabry disease are episodes of neuropathic pain reported in up to 80% of classical hemizygous male patients and up to 65% of heterozygous female patients. No clear consensus exists within UK clinical practice for the assessment and management of pain in Fabry disease based on agreed clinical practice and clinical experience. Here we describe a modified Delphi initiative to establish expert consensus on management of pain in Fabry disease in the UK clinical setting.

METHODS

Delphi panel members were identified based on their demonstrated expertise in managing adult or paediatric patients with Fabry disease in the UK and recruited by an independent third-party administrator. Ten expert panellists agreed to participate in two survey rounds, during which they remained anonymous to each other. Circulation of the questionnaires, and collection and processing of the panel's responses were conducted between September 2021 and December 2021. All questions required an answer.

RESULTS

The Delphi panel reached a consensus on 21 out of 41 aspects of pain assessment and management of pain in Fabry disease. These encompassed steps in the care pathway from the goals of therapy through to holistic support, including the use of gabapentin and carbamazepine as first-line analgesic medications for the treatment of neuropathic pain in Fabry disease, as well as the proactive management of symptoms of anxiety and/or depression associated with Fabry pain.

CONCLUSIONS

The consensus panel outcomes reported here have highlighted strengths in current UK clinical practice, along with unmet needs for further research and agreement. This consensus is intended to prompt the next steps towards developing clinical guidelines.

Renal and Electrolyte Disorders and the Nervous System

OBJECTIVE

Neurologic complications are a major contributor to death and disability in patients with renal disease. Oxidative stress, endothelial dysfunction, accelerated arteriosclerosis, and uremic inflammatory milieu affect both the central and peripheral nervous systems. This article reviews the unique contributions of renal impairment to neurologic disorders and their common clinical manifestations as the prevalence of renal disease increases in a globally aging population.

LATEST DEVELOPMENT

Advances in the understanding of the pathophysiologic interplay between the kidneys and brain, also referred to as the kidney-brain axis, have led to more widespread recognition of associated changes in neurovascular dynamics, central nervous system acidification, and uremia-associated endothelial dysfunction and inflammation in the central and peripheral nervous systems. Acute kidney injury increases mortality in acute brain injury to nearly 5 times that seen in matched controls. Renal impairment and its associated increased risks of intracerebral hemorrhage and accelerated cognitive decline are developing fields. Dialysis-associated neurovascular injury is increasingly recognized in both continuous and intermittent forms of renal replacement therapy, and treatment strategies for its prevention are evolving.

ESSENTIAL POINTS

This article summarizes the effects of renal impairment on the central and peripheral nervous systems with special considerations in acute kidney injury, patients requiring dialysis, and conditions that affect both the renal and nervous systems.

Fabry Disease and Central Nervous System Involvement: From Big to Small, from Brain to Synapse

Fabry disease (FD) is an X-linked lysosomal storage disorder (LSD) secondary to mutations in the GLA gene that causes dysfunctional activity of lysosomal hydrolase α-galactosidase A and results in the accumulation of globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3). The endothelial accumulation of these substrates results in injury to multiple organs, mainly the kidney, heart, brain and peripheral nervous system. The literature on FD and central nervous system involvement is scarce when focusing on alterations beyond cerebrovascular disease and is nearly absent in regard to synaptic dysfunction. In spite of that, reports have provided evidence for the CNS’ clinical implications in FD, including Parkinson’s disease, neuropsychiatric disorders and executive dysfunction. We aim to review these topics based on the current available scientific literature.

Fabry's Disease: The Utility of a Multidisciplinary Screening Approach

(1) Background: As a lysosomal storage disorder, Fabry’s disease (FD) shows variable clinical manifestations. We applied our multidisciplinary approach to identify any organ damage in a sample of adult patients with different pathogenic variants. (2) Methods: 49 participants (mean age 44.3 ± 14.2 years; 37 females), underwent a multidimensional clinical and instrumental assessment. (3) Results: At diagnosis, mean enzymatic activity was 5.2 ± 4.6 nM/mL/h in females and 1.4 ± 0.5 nM/mL/h in males (normal values > 3.0), whereas globotriaosylsphingosine was 2.3 ± 2.1 nM/L in females and 28.7 ± 3.5 nM/L in males (normal values < 2.0). Overall, cardiovascular, neurological, and audiological systems were the most involved, regardless of the variant detected. Patients with classic variants (10) showed typical multiorgan involvement and, in some cases, prevalent organ damage (cardiovascular, neurological, renal, and ocular). Those with late-onset variants (39) exhibited lower occurrence of multiorgan impairment, although some of them affected the cardiovascular and neurological systems more. In patients with lower enzymatic activity, the most frequent involvement was neurological, followed by peripheral vascular disease. (4) Conclusions: FD patients exhibited wide phenotypic variability, even at single-organ level, likely due to the individual genetic mutation, although other factors may contribute. Compared to the conventional management, a multidisciplinary approach, as that prompted at our Center, allows one to achieve early clinical detection and management.

Screening of Fabry disease in patients with chronic kidney disease in Japan

BACKGROUND

Fabry disease (FD), an X-linked lysosomal storage disorder caused by a deficiency in alfa-galactosidase A (α-Gal A) activity due to mutations in the GLA gene, has a prevalence of 0-1.69% in patients undergoing haemodialysis; however, its prevalence in patients with chronic kidney disease (CKD) Stages 1-5 is unknown.

METHODS

Serum α-Gal A activity analysis and direct sequencing of GLA were used to screen for FD in 2122 male patients with CKD, including 1703 patients with CKD Stage 5D and 419 with CKD Stages 1-5. The correlation between serum α-Gal A activity and confounding factors in patients with CKD Stages 1-5 was evaluated.

RESULTS

FD prevalence rates in patients with CKD Stage 5D and CKD Stages 1-5 were 0.06% (1/1703) and 0.48% (2/419), respectively. A patient with CKD Stage 5D exhibited a novel GLA mutation, p.Met208Arg, whereas two patients with CKD Stages 1-5 had c.370delG and p.Met296Ile. p. Met208Arg caused moderate structural changes in the molecular surface region near the substituted amino acid residue but did not affect the catalytic residues Asp170 and Asp231 in α-Gal A. Serum α-Gal A activity in patients with CKD Stages 1-5 was inversely correlated with age (P < 0.0001) but directly correlated with estimated glomerular filtration rate (P < 0.0001).

CONCLUSIONS

FD prevalence was much higher in male patients with CKD Stages 1-5 than in those with CKD Stage 5D. FD screening in patients with CKD Stages 1-5 may improve patient survival, decreasing the number of patients with CKD Stage 5D.

Review of Mechanisms, Pharmacological Management, Psychosocial Implications, and Holistic Treatment of Pain in Fabry Disease

Fabry disease is a progressive X-linked lysosomal storage disease caused by a mutation in the GLA gene, encoding the lysosomal hydrolase α-galactosidase A. The consequent reduced enzyme activity results in the toxic accumulation of glycosphingolipids, particularly globortriaosylceramide (Gb3 or GL3), in blood vessels, renal epithelia, myocardium, peripheral nervous system, cornea and skin. Neuropathic pain is the most common manifestation of Fabry disease and can be extremely debilitating. This often develops during childhood and presents with episodes of burning and sharp pain in the hands and feet, especially during exercise and it is worse with increased heat or fever. It is thought to be due to ischaemic injury and metabolic failure, leading to the disruption of neuronal membranes and small fibre neuropathy, caused by a reduced density of myelinated Aδ and unmyelinated C-fibres and alterations in the function of ion channels, mediated by Gb3 and lyso Gb3. It is important to confirm small fibre neuropathy before any Fabry disease treatment modality is considered. There is a clinical need for novel techniques for assessing small fibre function to improve detection of small fibre neuropathy and expand the role of available therapies. The current Fabry disease guidelines are in favour of pharmacological management as the first-line treatment for pain associated with Fabry disease. Refractory cases would benefit from a rehabilitation approach with interdisciplinary input, including medical, physiotherapy and psychological disciplines and including a Pain Management Programme.

Fabry disease-associated globotriaosylceramide induces mechanical allodynia via activation of signaling through proNGF-p75NTR but not mature NGF-TrkA

Fabry disease (FD) is an X-linked metabolic storage disorder arising from the deficiency of lysosomal α-galactosidase A, which leads to the gradual accumulation of glycosphingolipids, mainly globotriaosylceramide (Gb3), throughout the body. Pain in the extremities is an early symptom of FD; however, the underlying pathophysiological mechanisms remain unknown. α-Galactosidase A knockout animals exhibit nociceptive behaviors, with enhanced expression levels of several ion channels. These characteristics are observed in animals treated with nerve growth factor (NGF). Here, we aimed to elucidate the potential of NGF signaling as a cause of FD-associated pain, using intraplantar Gb3-treated mice displaying mechanical allodynia. Treatment with a neutralizing antibody against a precursor of NGF (proNGF) or its receptor, p75 neurotrophin receptor (p75NTR), resulted in the recovery from Gb3-induced pain. Conversely, anti-NGF and anti-tropomyosin receptor kinase A antibodies failed to exert analgesic effects. Gb3 injection had no effects on the expression levels of proNGF and p75NTR in the plantar skin and dorsal root ganglia, suggesting that Gb3 activates the pain pathway, possibly mediated through functional up-regulation of proNGF-p75NTR signaling. Furthermore, by pharmacological approaches using a protein kinase A (PKA) inhibitor and a cholesterol-removing agent, we found that p75NTR-phosphorylating PKA and lipid rafts for phosphorylated p75NTR translocation were required for Gb3-induced pain. These results suggest that acute exposure to Gb3 induces mechanical allodynia via activation of the proNGF-p75NTR pathway, which involves lipid rafts and PKA. Our findings provide new pathological insights into FD-associated pain, and suggest the need to develop therapeutic interventions targeting proNGF-p75NTR signaling.

DNA methylation impact on Fabry disease

BACKGROUND

Fabry disease (FD) is a rare X-linked disease caused by mutations in GLA gene with consequent lysosomal accumulation of globotriaosylceramide (Gb3). Women with FD often show highly heterogeneous symptoms that can manifest from mild to severe phenotype.

MAIN BODY

The phenotypic variability of the clinical manifestations in heterozygous women with FD mainly depends on the degree and direction of inactivation of the X chromosome. Classical approaches to measure XCI skewness might be not sufficient to explain disease manifestation in women. In addition to unbalanced XCI, allele-specific DNA methylation at promoter of GLA gene may influence the expression levels of the mutated allele, thus impacting the onset and the outcome of FD. In this regard, analyses of DNA methylation at GLA promoter, performed by approaches allowing distinction between mutated and non-mutated allele, may be much more informative. The aim of this review is to critically evaluate recent literature articles addressing the potential role of DNA methylation in the context of FD. Although up to date relatively few works have addressed this point, reviewing all pertinent studies may help to evaluate the importance of DNA methylation analysis in FD and to develop new research and technologies aimed to predict whether the carrier females will develop symptoms.

CONCLUSIONS

Relatively few studies have addressed the complexity of DNA methylation landscape in FD that remains poorly investigated. The hope for the future is that ad hoc and ultradeep methylation analyses of GLA gene will provide epigenetic signatures able to predict whether pre-symptomatic female carriers will develop symptoms thus helping timely interventions.

Neuropathic Pain: From Mechanisms to Treatment

Neuropathic pain caused by a lesion or disease of the somatosensory nervous system is a common chronic pain condition with major impact on quality of life. Examples include trigeminal neuralgia, painful polyneuropathy, postherpetic neuralgia, and central poststroke pain. Most patients complain of an ongoing or intermittent spontaneous pain of, for example, burning, pricking, squeezing quality, which may be accompanied by evoked pain, particular to light touch and cold. Ectopic activity in, for example, nerve-end neuroma, compressed nerves or nerve roots, dorsal root ganglia, and the thalamus may in different conditions underlie the spontaneous pain. Evoked pain may spread to neighboring areas, and the underlying pathophysiology involves peripheral and central sensitization. Maladaptive structural changes and a number of cell-cell interactions and molecular signaling underlie the sensitization of nociceptive pathways. These include alteration in ion channels, activation of immune cells, glial-derived mediators, and epigenetic regulation. The major classes of therapeutics include drugs acting on α₂δ subunits of calcium channels, sodium channels, and descending modulatory inhibitory pathways.

Diagnosis and Screening of Patients with Fabry Disease

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by absence or deficient activity of α-galactosidase A (α-Gal A) due to mutations in the α-galactosidase A gene (GLA), leading to progressive accumulation of globotriaosylceramide (Gb3) in tissues and organs including heart, kidney, the eyes, vascular endothelium, the nervous system and the skin. Cardiac involvement is leading to fatal complications and reduced life expectancy. FD is treatable with disease-specific treatment (enzyme replacement therapy (ERT) or with chaperone therapy). Therefore, the early diagnosis of FD is crucial for reducing the morbidity and mortality. Screening of high-risk populations (eg, patients with unexplained left ventricular hypertrophy (LVH), young patients with unexplained stroke, and patients with unexplained renal failure proteinuria or microalbuminuria) yields good results. The diagnostic algorithm is gender-specific. Initially, the measurement of α-Gal A activity is recommended in males, and optionally in females. In males with non-diagnostic residual activity (5–10%) activity, genetic testing is afterwards done for confirming the diagnosis. In fact, diagnosis of FD is not possible without genetic testing for both males and females. Globotriaosysphingosine (lyso-Gb3) for identification of atypical FD variants and high- sensitive troponin T (hsTNT) for identification of cardiac involvement are also important diagnostic biomarkers. The aim of this review was to provide an update on diagnosis and screening of patients with FD.

Effectiveness of immunosuppressive therapy for nephrotic syndrome in a patient with late-onset Fabry disease: a case report and literature review

BACKGROUND

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by mutations of the GLA gene, followed by deficiency in α-galactosidase A (α-gal) activity. Nephrotic syndrome, as the renal phenotype of FD, is unusual. Here, we report the rare case of a patient with FD with nephrotic syndrome whose proteinuria disappeared by immunotherapy.

CASE PRESENTATION

A 67-year-old Japanese man was admitted to our hospital because of emesis, abdominal pain, and facial edema due to nephrotic syndrome. The patient was diagnosed with focal segmental glomerulosclerosis (FSGS) by renal biopsy before being diagnosed with FD, and immunotherapy was initiated. After treatment, the kidney biopsy results showed typical glycosphingolipid accumulation in the podocytes of this patient. The white blood cell α-gal activity was very low, and genetic analysis revealed a GLA gene variant (M296I), which is known as a late-onset genetic mutation of FD. Immunotherapy (steroids and cyclosporine A) dramatically improved the massive proteinuria. Currently, he has been undergoing enzyme replacement therapy, and his proteinuria has further decreased. There is the possibility that other nephrotic syndromes, such as minimal change nephrotic syndrome or FSGS, may co-exist in this patient.

CONCLUSIONS

We experienced the rare case of a FD patient whose nephrotic syndrome disappeared by immunotherapy. These findings suggest that immunosuppressive treatment may be considered if nephrotic syndrome develops, even in patients with FD.

Globotriaosylceramide-induced reduction of KCa1.1 channel activity and activation of the Notch1 signaling pathway in skin fibroblasts of male Fabry patients with pain

BACKGROUND

Fabry disease (FD) is an X-linked lysosomal storage disorder that leads to cellular globotriaosylceramide (Gb3) accumulation due to mutations in the gene encoding α-galactosidase A. Trigger-induced acral burning pain is an early FD symptom of unknown pathophysiology. We aimed at investigating the potential role of skin fibroblasts in nociceptor sensitization.

PATIENTS AND METHODS

We enrolled 40 adult FD patients and ten healthy controls, who underwent a 6-mm skin punch biopsy at the lower leg. Dermal fibroblasts were cultivated and analyzed for Gb3 load. Fibroblast electrical activity was assessed using patch-clamp analysis at baseline and upon incubation with agalsidase-α for 24 h. We investigated gene expression of CC motif chemokine ligand 2 (CCL2), Ca²⁺activated K⁺-channel 1.1 (K_Ca1.1), interferone-γ (IFN-γ), transforming growth factor-β1 (TGF-β1), and transmembrane receptor notch homolog 1 (Notch1) using quantitative real-time-PCR, and protein levels of K_Ca1.1 by ELISA. Gene expression was determined at baseline and after fibroblast stimulation with tumor necrosis factor-α (TNF), modeling inflammation as a common pain trigger in FD.

RESULTS

Total Gb3 load was higher in FD fibroblasts than in control fibroblasts (p < .01). Upon increase of intracellular Ca²⁺ concentrations, we detected differential electrical activity of K_Ca1.1 in fibroblasts obtained from patients with FD. Gene expression (p < .05) and protein levels of K_Ca1.1 (p < .05) were higher in fibroblasts from FD patients compared to control fibroblasts, whereas electric channel activity was lower in FD fibroblasts. After incubation with agalsidase-α, we observed an over-proportionate increase of K_Ca1.1 activity in FD fibroblasts reaching 7-fold the currents of control cells (p < .01). Gene expression studies revealed higher mRNA levels of CCL2, INF-γ, and Notch1 in FD fibroblasts compared to controls at baseline and after TNF incubation (p < .05 each), while TGF-β1 was higher in FD fibroblasts only after incubation with TNF (p < .05).

CONCLUSIONS

Gb3 deposition in skin fibroblasts may impair K_Ca1.1 activity and activate the Notch1 signaling pathway. The resulting increase in pro-inflammatory mediator expression may contribute to cutaneous nociceptor sensitization as a potential mechanism of FD-associated pain.

Fibromyalgia syndrome and small fiber, early or mild sensory polyneuropathy

INTRODUCTION

Pain mechanisms in fibromyalgia syndrome (FMS) are not clearly understood. Growing evidence appears to suggest a role for small fiber polyneuropathy (SFPN) in some FMS patients, as measured by epidermal nerve fiber density (ENFD). We aimed to better characterize and distinguish the subset of patients with both fibromyalgia and small fiber, early or mild sensory polyneuropathy (FM-SFSPN).

METHODS

155 FMS patients with neuropathic symptoms completed a Short Form McGill Questionnaire and visual analog scale in addition to having skin biopsies, nerve conduction studies (NCS), and serologic testing.

RESULTS

Sural and medial plantar (MP) response amplitudes correlated with ENFD, with markers of metabolic syndrome being more prevalent in this subset of patients. Pain intensity and quality did not distinguish patients.

DISCUSSION

The FM-SFSPN subset of patients may be identified through sural and MP sensory NCS and/or skin biopsy but cannot be identified by pain features and intensity. Muscle Nerve 58: 625-630, 2018.

Neuro-Otological and Peripheral Nerve Involvement in Fabry Disease

Fabry disease (FD) is an X-linked lysosomal storage disease, with multisystemic glycosphingolipids deposits. Neuro-otological involvement leading to hearing loss and vestibular dysfunctions has been described, but there is limited information about the frequency, site of lesion, or the relationship with peripheral neuropathy. The aim was to evaluate the presence of auditory and vestibular symptoms, and assess neurophysiological involvement of the VIII cranial nerve, correlating these findings with clinical and neurophysiological features of peripheral neuropathy. We studied 36 patients with FD with a complete neurological and neuro-otological evaluation including nerve conduction studies, quantitative sensory testing (to evaluate small fiber by warm and cold threshold detection and cold and heat pain), vestibular evoked myogenic potentials, videonistagmography, audiometry and brainstem auditory evoked potentials. Neuro-otologic symptoms included hearing loss (22.2%), vertigo (27.8%) or both (25%). An involvement of either cochlear or vestibular function was identified in most patients (75%). In 70% of our patients the involvement of both cochlear and vestibular function could not be explained by a neural or vascular mechanism. Small fiber neuropathy was identified in 77.7%. There were no significant associations between neuro-otological and QST abnormalities. Neuro-otologic involvement is frequent and most likely under-recognized in patients with FD. It lacks a specific neural or vascular pattern, suggesting multi-systemic, end organ damage. Small fiber neuropathy is an earlier manifestation of FD, but there is no correlation between the development of neuropathy and neuro-otological abnormalities.

[The neurological manifestations of Fabry disease. A review]

Fabry disease (Anderson-Fabry disease) is an X-linked recessive lysosomal storage disorder resulting from deficient activity of lysosomal hydrolase, alpha-galactosidase A (alpha-Gal A), which leads to progressive accumulation of globotriaosylceramide (Gb3) in various cells, predominantly endothelial and vascular smooth muscle cells, with clinical manifestations affecting major organs including the central nervous system. Manifestations of Fabry disease include progressive renal and cardiac insufficiency, neuropathic pain, stroke and cerebral disease, skin and gastrointestinal symptoms. Clinical onset usually occurs in childhood, but many severe patients are diagnosed in adulthood. Females may be severely affected as males and both may die prematurely due to stroke, heart disease and renal failure. Early recognition of symptoms, enzyme activity levels, concentration of Gb3 levels in the blood, urine and skin biopsies, as well as genetic testing (GLA gene) enable establishment of early diagnosis and therapeutic intervention with enzyme replacement therapy. Enzyme replacement therapy can stabilize or reduce the progression of the disease. Early therapy may prevent complications of the disease.

Electroneuromyographic Features in Fabry Disease: A Retrospective Review

INTRODUCTION

Fabry disease (FD) is an X-linked recessive inherited disorder characterized by lysosomal alpha-galactosidase deficiency. The purpose of our study was to assess and compare the electroneuromyographic (ENMG) findings of 15 patients with Fabry disease and the electroneurographic (ENG) findings of 15 healthy controls. We have not encountered any similar study in the medical literature of our country. Therefore, we believe that our study will contribute to national literature.

METHODS

Fifteen patients with Fabry disease, 13 females and 2 males and 15 healthy controls, 13 females and 2 males, were included in the study. The definite diagnosis of patients with Fabry disease was made based on the enzyme level and genetic mutation. The patients with Fabry disease were examined with ENMG, while the healthy control group was examined with ENG. In the patients with a normal ENMG examination, neuropathic pain was attributed to the small fiber involvement.

RESULTS

Patients with Fabry disease had neuropathic pain (LANSS score≥12). While neurological examination was normal in eight patients, glove- and stocking-type hypoesthesia and decreased deep tendon reflexes were observed in five and two patients, respectively. Axonal polyneuropathy was detected in one patient. The ENMG examinations of the other patients were normal. Enzyme replacement therapy could not be initiated in one patient because of pregnancy. The neurological examination of the healthy control group was normal. There was no statistically significant difference between the ENMG features of both groups (p>.05). As in other studies, a routine ENMG examination was normal in our patients with early-stage Fabry disease. Neuropathic pain, seen in patients with Fabry disease in literature, is thought to be due to small fiber involvement.

CONCLUSION

Fabry disease should be considered in the differential diagnosis of patients with neuropathic pain at young ages. It should be kept in mind that ENMG examination can be normal at the early stages. Quantitative sensory test, autonomic tests (R-R interval and sympathetic skin response) and skin biopsy should be performed in such cases. In our country, pediatric physicians work on Fabry disease more than physicians dealing with Fabry disease in adults. Therefore, in this retrospective study, we aimed to draw adult and pediatric neurologists' attention to Fabry disease.

The Fabry disease-associated lipid Lyso-Gb3 enhances voltage-gated calcium currents in sensory neurons and causes pain

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Gb3 and Lyso-Gb3, plasma lipids accumulating in Fabry disease, cause mechanical allodynia in mice.

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Lyso-Gb3 elevates intracellular calcium level in sensory neurons.

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Lyso-Gb3 enhances voltage-dependent calcium currents in small-diameter DRG neurons.

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Direct effects of lyso-Gb3 on sensory neurons may contribute to the pain of Fabry disease.

Fabry disease is an X-linked lysosomal storage disorder characterised by accumulation of glycosphingolipids, and accompanied by clinical manifestations, such as cardiac disorders, renal failure, pain and peripheral neuropathy. Globotriaosylsphingosine (lyso-Gb3), a deacylated form of globotriaosylceramide (Gb3), has emerged as a marker of Fabry disease. We investigated the link between Gb3, lyso-Gb3 and pain. Plantar administration of lyso-Gb3 or Gb3 caused mechanical allodynia in healthy mice. In vitro application of 100 nM lyso-Gb3 caused uptake of extracellular calcium in 10% of sensory neurons expressing nociceptor markers, rising to 40% of neurons at 1 μM, a concentration that may occur in Fabry disease patients. Peak current densities of voltage-dependent Ca²⁺ channels were substantially enhanced by application of 1 μM lyso-Gb3. These studies suggest a direct role for lyso-Gb3 in the sensitisation of peripheral nociceptive neurons that may provide an opportunity for therapeutic intervention in the treatment of Fabry disease-associated pain.

A Case of Cerebral Aneurysmal Subarachnoid Hemorrhage in Fabry's Disease

We report an unusual case of cerebral aneurysmal subarachnoid hemorrage (SAH) with Fabry's disease. A 42-year-old woman presented with aneurysmal SAH originated from a saccular aneurysm of the right posterior communicating artery. The patient was treated by an endovascular coil embolization of aneurysm. Postoperatively the patient recovered favorably without any neurological deficit. During her admission, the patient had a sign of proteinuria in urine analysis. The pathologic findings of kidney needle biopsy implied nephrosialidosis (mucolipidosis of lysosomal stroage disease), which is consistent with a Fabry's disease. It is uncommon that Fabry's disease is presented with aneurysmal SAH, especially in middle-aged patients, but could be a clinical concern. Further investigations are needed to reveal risk factors, vascular anatomy, and causative mechanisms of Fabry's disease with aneurysmal SAH.

Cabergoline reduces cell viability in non functioning pituitary adenomas by inhibiting vascular endothelial growth factor secretion

Dopamine (DA) therapy of non-functioning pituitary adenomas (NFA) can result in tumor stabilization and shrinkage. However, the mechanism of action is still unknown. Previous evidence showed that DA can inhibit pituitary vascular endothelial growth factor expression (VEGF), that may be involved in pituitary tumor growth. The aim of our study was to clarify whether VEGF secretion modulation might mediate the effects of DA agonists on cell proliferation in human NFA. We assessed DA receptor subtype 2 (DR2) expression in 20 NFA primary cultures, where we also investigated the effects of a selective DR2 agonist, cabergoline (Cab), on VEGF secretion and on cell viability. All NFA samples expressed α-subunit and DR2 was expressed in 11 samples. In DR2 expressing tumors, Cab significantly reduced cell viability (-25%; P < 0.05) and VEGF secretion (-20%; P < 0.05). These effects were counteracted by treatment with the DA antagonist sulpiride. Cab antiproliferative effects were blocked by VEGF. Our data demonstrate that Cab, via DR2, inhibits cell viability also by reducing VEGF secretion in a selected group of NFA, supporting that DA agonists can be useful in the medical therapy of DR2 expressing NFA.

Awareness of Fabry disease among rheumatologists--current status and perspectives

Fabry disease is an inherited disorder of lipid metabolism caused by deficient activity of the lysosomal enzyme α-galactosidase A. Burning peripheral pain with triggered crises of excruciating pain and gastrointestinal dysmotility point to Fabry small fiber neuropathy; angiokeratoma, corneal deposits, and hypohidrosis are other common early manifestations. Progressive dysfunction of the kidneys, heart, and/or brain develops in adulthood. Diagnosis is often delayed which is of great concern, as therapeutic outcomes with enzyme replacement therapy are generally more favorable in early stages of Fabry disease. Results of a survey among 360 rheumatologists and pediatricians clinically managing patients with rheumatologic conditions demonstrate that Fabry manifestations are generally poorly recognized and that awareness of appropriate diagnostic tests is low. To raise awareness about the musculoskeletal aspects of Fabry disease among rheumatologists, the International Musculoskeletal Working Group on Lysosomal Storage Disorders has reviewed the current knowledge. We propose a diagnostic algorithm with burning pain in hands and feet and triggered attacks of excruciating pain as keystones. Evidence of autonomic nerve dysfunction and simple temperature sensitivity testing can provide important diagnostic clues. Multi-systemic involvement should be explored by taking a detailed medical history, including family history, and performing a thorough physical examination and appropriate laboratory workup. Confirmatory tests include the α-Gal A enzyme activity assay (males) and genetic testing (females). We propose that medical specialists use our diagnostic algorithm when evaluating individuals with peripheral neuropathic pain.

Role of cardiac MRI in evaluating patients with Anderson-Fabry disease: assessing cardiac effects of long-term enzyme replacement therapy

PURPOSE

Anderson-Fabry disease is a multisystemic disorder of lipid metabolism secondary to X-chromosome alterations and is frequently associated with cardiac manifestations such as left ventricular (LV) hypertrophy, gradually leading to an alteration in cardiac performance. The purpose of this study was to monitor, using magnetic resonance imaging (MRI), any changes produced by enzyme replacement therapy with agalsidase beta at the cardiac level in patients with Anderson-Fabry disease.

MATERIALS AND METHODS

Sixteen (ten men, six women) patients with genetically confirmed Anderson-Fabry disease underwent cardiac MRI before starting enzyme replacement therapy (baseline study) and after 48 months of treatment with agalsidase beta at the dose of 1 mg/kg (follow-up study).

RESULTS

After 48 months of treatment, a significant reduction in LV mass and wall thickness was observed: 187±59 g vs. 149±44 g, and 16±3 mm vs. 13±3 mm, respectively. A significant reduction in T2 relaxation time was noted at the level of the interventricular septum (81±3 ms vs. 67±7 ms), at the apical level (80±8 ms vs. 63±6 ms) and at the level of the lateral wall (82±8 ms vs. 63±10 ms) (p<0.05). No significant variation was observed in ejection fraction between the two studies (65±3% vs. 64±2%; p>0.05) (mean bias 1.0); however, an improvement was noted in the New York Heart Association (NYHA) class of the majority of patients (12/16) (p<0.05).

CONCLUSIONS

In patients with Anderson-Fabry disease undergoing enzyme replacement therapy with agalsidase beta, MRI documented a significant reduction in myocardial T2 relaxation time, a significant decrease in maximal myocardial thickness and in total LV mass. MRI did not reveal significant improvements in LV global systolic function; however, improvement in NYHA functional class was noted, consistent with improved diastolic function.

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.

Localized aquadynia responsive to clonidine in a 13-year-old girl

A 13-year-old girl sought medical care for pain in both palms that consistently occurred after brief exposure to water and resolved spontaneously 20 to 30 minutes after immersion. The pain was not associated with wrinkling of the palms. After excluding other causes of acrodynia and water-induced discomfort, we diagnosed the patient as having idiopathic localized aquadynia. Treatment with systemic clonidine led to a substantial improvement in her symptoms. To our knowledge, this patient represents the only fifth reported case of aquadynia and the first child affected by this enigmatic condition.

Nervous system and Fabry disease, from symptoms to diagnosis: damage evaluation and follow-up in adult patients, enzyme replacement, and support therapy

The X-linked genetic Fabry disease causes multiorgan lesions due to intracellular storage of the substrate globotriaosylceramide. Neurological involvement ranges from painful, small fiber neuropathy to cerebrovascular disorders to multifocal aggressive forms. Disease identification through proper differential diagnosis and timely assessment of organ damage should guide a careful treatment planning. Mainstay treatment, include enzyme replacement and support therapy. Neurologists have a pivotal role in early instrumental and clinical detection of organ damage. A panel of experts has developed a set of consensus recommendations to guide the approach of neurologists to Fabry disease.

Mutation patterns in human α-galactosidase A

A way to study the mutation pattern is to convert a 20-letter protein sequence into a scalar protein sequence, because the 20-letter protein sequence is neither vector nor scalar while a promising way to study patterns is in numerical domain. In this study, we use the amino-acid pair predictability to convert α-galactosidase A with its 137 mutations into scalar sequences, and analyse which amino-acid pairs are more sensitive to mutation. Our results show that the unpredictable amino-acid pairs are more sensitive to mutation, and the mutation trend is to narrow the difference between predicted and actual frequency of amino-acid pairs.

Fabry disease diagnostic guideline

A Fabry-kór a lizoszomális tárolási betegségek csoportjába tartozó, X-kromoszómához kötötten, recesszív módon öröklődő betegség, amely a globotriaosylceramid felhalmozódásához vezet a szervezet legkülönbözőbb szöveteiben. A betegség első tünetei többnyire gyermekkorban jelentkeznek, a progresszió során a betegek súlyos szervi károsodásokkal és korai halálozással számolhatnak. Elsősorban fiúk és férfiak érintettek, azonban a betegség tüneteit heterozigóta nők esetében is megfigyelhetjük, de náluk a kórkép súlyossága változó, általában enyhébb lefolyású. Az enzimpótló kezelések megjelenése szükségessé tette, hogy részletes diagnosztikus és terápiás protokollt dolgozzunk ki. A jelen dolgozatban megjelenő ajánlásokat egy, a magyarországi Fabry-betegek kezelésében aktívan részt vevő orvosokból, a diagnosztika területén dolgozó biológosukból és egyéb szakemberekből álló multidiszciplináris munkacsoport foglalta össze. A munkacsoport áttekintette a korábbi klinikai tanulmányokat, a publikált vizsgálatokat és a közelmúltban megjelent nemzetközi és nemzeti útmutatókat.

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.

Inherited metabolic disorders and cerebral infarction

The association of genetic factors and cerebral infarction (CI) has long been established. A positive family history alone is a recognized risk factor for CI and vascular events in general. However, there are certain inherited conditions that further increase the risk of stroke. These conditions are generally metabolic and mitochondrial genetic defects that have variable modes of inheritance. This article reviews major inherited metabolic disorders that predispose an individual to CI. Ten main conditions will be discussed: Fabry's disease, cerebrotendinous xanthomatosis, tangier disease, familial hypercholesterolemia, homocystinuria, methylmalonic acidemia, glutaric aciduria type I, propionic acidemia, ornithine transcarbamylase deficiency and mitochondrial encephalopathy, lactic acidosis and stroke-like phenomenon.