Prevalence of Fabry disease and GLA c.196G>C variant in Japanese stroke patients

Diagnosis of Inherited Metabolic Disease in Older Patients: A Systematic Literature Review

Inherited metabolic diseases (IMDs) are genetic disorders that disrupt biochemical processes in the human body, due to pathogenic variants in genes encoding enzymes or transporters. While IMDs are mostly diagnosed in infancy or childhood, there is an increasing number of diagnoses in adult patients. Delayed diagnosis, particularly in older patients, may reflect the diagnostic odyssey usually observed in rare diseases' patients and can result in complications and reduced quality of life for patients and their families. The aim of the study was to better characterize the diagnosis of IMDs in older patients (≥ 65 years). We conducted a systematic literature review (SLR) to examine the diagnosis and clinical presentation of IMDs in patients aged 65 and older. We searched databases like PubMed, Embase, and Lilacs for relevant studies from 1965 to 2023. A total of 260 articles were included, representing 293 patients with a median age of 69 years at diagnosis. From this SLR, 67 different diagnoses have been reported. The most frequently reported diseases were Fabry disease, alkaptonuria, Gaucher disease, mitochondrial disorders, and glycogen storage disease type V. Median diagnostic delay was 14.5 years with a wide range of 1-91 years. Musculoskeletal symptoms were the most frequently reported, followed by neurological and cardiovascular symptoms. Our findings underscore the importance of recognizing IMDs in older patients and the need for awareness among healthcare providers to improve diagnosis and patient care. Future guidelines and teaching programs should incorporate metabolic investigations for older patients presenting with symptoms suggestive of IMDs.

Cryptogenic strokes and neurological symptoms of Fabry disease

Introduction

Fabry disease (FD) is the second most common lysosomal storage disorder. It mainly affects young people. FD can be characterized by neurological symptoms that can occur in both the central and peripheral nervous systems. Cerebrovascular involvement is common in FD and is considered an important cause of cryptogenic strokes. This study aimed to describe the neurological symptoms in patients with FD in general and, specifically, to determine the frequency of association between this disease and cerebrovascular manifestations in our environment.

Materials and methods

This retrospective, observational, cross-sectional study included all patients in the FD registry of the nephrology and cardiology Departments of our center. A descriptive analysis of demographic, neurological, clinical, and neuroimaging variables was performed, with a particular focus on their association with stroke or other cerebrovascular events prior to diagnosis.

Results

A total of 25 patients were included, with 14 (68%) of them being women. The median age of the patients was 52 years (relative intensity of collaboration [RIC] = 24.5). The patients belonged to five families with specific galactosidase alpha gene (GLA) mutations. Neuroimaging was performed in 13 (52%) patients, most of whom did not have neurological symptoms but had normal imaging results. Only 2 (8%) patients had nonspecific white matter hyperintensities. Among the 11 (44%) patients with neurological involvement, the most common symptom was pain in the extremities (32%). Stroke was identified in only one patient (4%), which occurred prior to the diagnosis of FD and was determined to be of cardioembolic etiology.

Discussion

FD is found to be associated with several neurological symptoms. In our study, the most common neurological symptom was limb pain, which had varied characteristics. On the other hand, the incidence of stroke was significantly lower than that expected.

Expanding the Neurological Phenotype of Anderson-Fabry Disease: Proof of Concept for an Extrapyramidal Neurodegenerative Pattern and Comparison with Monogenic Vascular Parkinsonism

Anderson-Fabry disease (AFD) is a genetic sphingolipidosis involving virtually the entire body. Among its manifestation, the involvement of the central and peripheral nervous system is frequent. In recent decades, it has become evident that, besides cerebrovascular damage, a pure neuronal phenotype of AFD exists in the central nervous system, which is supported by clinical, pathological, and neuroimaging data. This neurodegenerative phenotype is often clinically characterized by an extrapyramidal component similar to the one seen in prodromal Parkinson's disease (PD). We analyzed the biological, clinical pathological, and neuroimaging data supporting this phenotype recently proposed in the literature. Moreover, we compared the neurodegenerative PD phenotype of AFD with a classical monogenic vascular disease responsible for vascular parkinsonism and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). A substantial difference in the clinical and neuroimaging features of neurodegenerative and vascular parkinsonism phenotypes emerged, with AFD being potentially responsible for both forms of the extrapyramidal involvement, and CADASIL mainly associated with the vascular subtype. The available studies share some limitations regarding both patients' information and neurological and genetic investigations. Further studies are needed to clarify the potential association between AFD and extrapyramidal manifestations.

The Role of α3β1 Integrin Modulation on Fabry Disease Podocyte Injury and Kidney Impairment

Podocyte dysfunction plays a crucial role in renal injury and is identified as a key contributor to proteinuria in Fabry disease (FD), primarily impacting glomerular filtration function (GFF). The α3β1 integrins are important for podocyte adhesion to the glomerular basement membrane, and disturbances in these integrins can lead to podocyte injury. Therefore, this study aimed to assess the effects of chloroquine (CQ) on podocytes, as this drug can be used to obtain an in vitro condition analogous to the FD. Murine podocytes were employed in our experiments. The results revealed a dose-dependent reduction in cell viability. CQ at a sub-lethal concentration (1.0 µg/mL) induced lysosomal accumulation significantly (p < 0.0001). Morphological changes were evident through scanning electron microscopy and immunofluorescence, highlighting alterations in F-actin and nucleus morphology. No significant changes were observed in the gene expression of α3β1 integrins via RT-qPCR. Protein expression of α3 integrin was evaluated with Western Blotting and immunofluorescence, demonstrating its lower detection in podocytes exposed to CQ. Our findings propose a novel in vitro model for exploring secondary Fabry nephropathy, indicating a modulation of α3β1 integrin and morphological alterations in podocytes under the influence of CQ.

Nationwide screening for Fabry disease in unselected stroke patients

Background and aims

Fabry disease (FD) is a rare X-linked lysosomal storage disorder caused by disease-associated variants in the alpha-galactosidase A gene (GLA). FD is a known cause of stroke in younger patients. There are limited data on prevalence of FD and stroke risk in unselected stroke patients.

Methods

A prospective nationwide study including 35 (78%) of all 45 stroke centers and all consecutive stroke patients admitted during three months. Clinical data were collected in the RES-Q database. FD was diagnosed using dried blood spots in a stepwise manner: in males—enzymatic activity, globotriaosylsphingosine (lyso-Gb3) quantification, if positive followed by GLA gene sequencing; and in females GLA sequencing followed by lyso-Gb3.

Results

986 consecutive patients (54% men, mean age 70 years) were included. Observed stroke type was ischemic 79%, transient ischemic attack (TIA) 14%, intracerebral hemorrhage (ICH) 7%, subarachnoid hemorrhage 1% and cerebral venous thrombosis 0.1%. Two (0.2%, 95% CI 0.02–0.7) patients had a pathogenic variant associated with the classical FD phenotype (c.1235_1236delCT and p.G325S). Another fourteen (1.4%, 95% CI 0.08–2.4) patients had a variant of GLA gene considered benign (9 with p.D313Y, one p.A143T, one p.R118C, one p.V199A, one p.R30K and one p.R38G). The index stroke in two carriers of disease-associated variant was ischemic lacunar. In 14 carriers of GLA gene variants 11 strokes were ischemic, two TIA, and one ICH. Patients with positive as compared to negative GLA gene screening were younger (mean 60±SD, min, max, vs 70±SD, min, max, P = 0.02), otherwise there were no differences in other baseline variables.

Conclusions

The prevalence of FD in unselected adult patients with acute stroke is 0.2%. Both patients who had a pathogenic GLA gene variant were younger than 50 years. Our results support FD screening in patients that had a stroke event before 50 years of age.

High-Risk Screening for Fabry Disease: A Nationwide Study in Japan and Literature Review

Fabry disease (FD) is an X-linked inherited disorder caused by mutations in the GLA gene, which encodes the lysosomal enzyme α-galactosidase A (α-Gal A). FD detection in patients at an early stage is essential to achieve sufficient treatment effects, and high-risk screening may be effective. Here, we performed high-risk screening for FD in Japan and showed that peripheral neurological manifestations are important in young patients with FD. Moreover, we reviewed the literature on high-risk screening in patients with renal, cardiac, and central neurological manifestations. Based on the results of this study and review of research abroad, we believe that FD can be detected more effectively by targeting individuals based on age. In recent years, the methods for high-risk screening have been ameliorated, and high-risk screening studies using GLA next-generation sequencing have been conducted. Considering the cost-effectiveness of screening, GLA sequencing should be performed in individuals with reduced α-Gal A activity and females with certain FD manifestations and/or a family history of FD. The findings suggest that family analysis would likely detect FD patients, although GLA sequencing of asymptomatic family members requires adequate genetic counseling.

Characteristics of Neurological Symptoms in Adult Japanese Patients with Fabry Disease

Objective Fabry disease (FD) is a hereditary lysosomal storage disease that has been highlighted as a possible etiology of stroke at a young age and presents with other various neurological symptoms. Since FD is rare, limited information is currently available on the prevalence of neurological symptoms in Japanese patients with FD. Therefore, we examined the characteristics of neurological symptoms and brain magnetic resonance imaging (MRI) findings in adult Japanese patients with FD. Methods This was a retrospective, single-center study. We reviewed neurological symptoms and brain MRI findings in the medical records of 12 adult Japanese patients with FD diagnosed by a gene analysis of the α-galactosidase gene. Results Ten out of 12 patients with FD presented with the following neurological symptoms: acroparesthesia (n=6), headache (n=5) [migraine (n=4)], hypohidrosis (n=5), and cerebral infarction (n=3). Two and three of the patients with migraine were complicated by ischemic stroke and coronary spastic angina, respectively. Five and 10 patients presented with periventricular hyperintensity and deep white matter hyperintensity, respectively, on brain MRI. Two out of eight patients had cerebral microbleeds. Seven out of 11 patients had a dilated basilar artery diameter on magnetic resonance angiography. There were no patients with the pulvinar hyperintensity sign. Conclusion Patients with FD present with various neurological symptoms. Headache, particularly migraine, might be a major neurological symptom in patients with FD. Since migraine, ischemic stroke, and coronary spastic angina might occur together in FD, caution is needed when administering triptan to FD patients with migraine.

High-risk screening for Anderson-Fabry disease in patients with cardiac, renal, or neurological manifestations

Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder caused by abnormalities in the α-galactosidase (Gal) A gene (GLA; MIM:300644). The reduced activity of the lysosomal enzyme, α-galactosidase A (α-Gal A) leads to classic early manifestations and vascular disease of the heart, kidneys, and brain. As a high-risk screening for symptomatic AFD using an enzymatic assay on dried blood spot samples, we enrolled 2325 individuals (803 females and 1522 males; median age: 66 years) with cardiac, renal, or neurological manifestations that met at least one of the following criteria: (a) family history of early-onset cardiovascular diseases; (b) typical classic manifestations, such as acroparesthesias, clustered angiokeratoma, cornea verticillata, and hypo-anhidrosis; (c) proteinuria; (d) receiving dialysis; (e) left ventricular hypertrophy on electrocardiography or echocardiography; or (f) history of stroke. Ninety-two patients displayed low α-Gal A activity. Four males and two females had different pathogenic GLA mutations (0.26%) including a novel mutation c.908-928del21. Four males (0.17%) harbored the GLA c.196G>C (p.E66Q) variant. This simple screening protocol using dried blood spot samples is useful for early diagnosis of AFD in high-risk and underdiagnosed patients suffering from various cardiac, renal, or neurological manifestations.

Fabry Disease: prevalence of affected males and heterozygotes with pathogenic GLA mutations identified by screening renal, cardiac and stroke clinics, 1995-2017

BACKGROUND

Fabry Disease (FD), an X linked lysosomal storage disease due to pathogenic α-galactosidase A (GLA) mutations, results in two major subtypes, the early-onset Type 1 'Classic' and the Type 2 'Later-Onset' phenotypes. To identify previously unrecognised patients, investigators screened cardiac, renal and stroke clinics by enzyme assays. However, some screening studies did not perform confirmatory GLA mutation analyses, and many included recently recognised 'benign/likely-benign' variants, thereby inflating prevalence estimates.

METHODS

Online databases were searched for all FD screening studies in high-risk clinics (1995-2017). Studies reporting GLA mutations were re-analysed for pathogenic mutations, sex and phenotype. Phenotype-specific and sex-specific prevalence rates were determined.

RESULTS

Of 67 studies, 63 that screened 51363patients (33943M and 17420F) and provided GLA mutations were reanalysed for disease-causing mutations. Of reported GLA mutations, benign variants occurred in 47.9% of males and 74.1% of females. The following were the revised prevalence estimates: among 36820 (23954M and 12866F) haemodialysis screenees, 0.21% males and 0.15% females; among 3074 (2031M and 1043F) renal transplant screenees, 0.25% males and no females; among 5491 (4054M and 1437F) cardiac screenees, 0.94% males and 0.90% females; and among 5978 (3904M and 2074F) stroke screenees, 0.13% males and 0.14% females. Among male and female screenees with pathogenic mutations, the type 1 Classic phenotype was predominant (~60%), except more male cardiac patients (75%) had type 2 Later-Onset phenotype.

CONCLUSIONS

Compared with previous findings, reanalysis of 63 studies increased the screenee numbers (~3.4-fold), eliminated 20 benign/likely benign variants, and provided more accurate sex-specific and phenotype-specific prevalence estimates, ranging from ~0.13% of stroke to ~0.9% of cardiac male or female screenees.