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

Expanded screening for Fabry disease in patients with chronic kidney disease not on dialysis: a multicenter Italian experience

Fabry disease (FD) is a progressive, multisystemic X-linked disorder caused by mutations in the GLA gene, often leading to renal failure. Although several screening programs have been conducted, the prevalence of FD in patients with chronic kidney patients who are not dependent on dialysis (NDD-CKD) is likely underestimated due to restrictive inclusion criteria and methodological shortcomings. This study aims to assess the prevalence of FD in NDD-CKD patients using an expanded screening approach. Ongoing outpatients attending Italian nephrology clinics were screened by assay of plasma α-galactosidase A (α-Gal A) activity. Genetic testing was also performed in all females and males with low α-Gal A activity. Inclusion criteria were: (1) females ≥18 years old; (2) males aged between 18 and 70 years; (3) NDD-CKD stages 1-5. Patients with histological diagnosis of glomerulonephritis or diagnosis of autosomal dominant polycystic kidney disease (ADPKD) were excluded. Demographic data and laboratory results were also collected. Among 385 NDD-CKD outpatients, 173 underwent screening. One patient with three family members carrying a novel mutation (c.320 A > G, p.Q107R); one patient with three family members carrying a silent mutation (c.48 T > G, p.L16L) and two patients with a missense mutation (c.376A > G, p.S126G), were identified. Overall, the prevalence of FD was 2.3%, increasing to 5.4% (10 in 183) with family screening. FD may be more common than previously believed, particularly within NDD-CKD populations. FD screening should be expanded to include NDD-CKD patients with known causes of CKD, such as hypertension and diabetes mellitus, and genetic testing should be routinely used for female patients.

Expert review in diagnostic, therapeutic and follow-up of Fabry disease in Latin America based on patient care standards

Background

Fabry disease (FD) is an X-linked lysosomal sphingolipidosis. It is caused by pathogenic variants in the GLA gene with a consequent deficiency of the enzyme α-galactosidase A, resulting in the pathological accumulation of glycolipids - mainly globotriosyl ceramide (GL-3, GB3) and its deacylated product, globotriaosylsphingosine (Lyso-Gb-3) - in plasma and in a wide variety of cell types throughout the human body; it is characterized as a chronic, multisystemic disease with progressive evolution, which causes deterioration of the patient's quality of life and decreases survival and life expectancy.In Latin America there are different limitations to the management of patients with Fabry disease, in most countries, access to diagnostic tools and treatment on time is complex and can sometimes suffer delays in its implementation. This situation is due to the high costs to health systems of follow-up and pharmacological therapy for Fabry patients, creating barriers to timely access.

Conclusions

Although medical criteria are fundamental in the choice of pharmacological therapy, the final decision should also rely on the patient's choice according to their expectations and the adherence and compliance with the treatment that they are willing to follow. As it has been described, there are currently three therapeutic options, for which the appropriate profile must be defined to achieve the best clinical outcomes, considering that it is a permanent treatment; experts consider that Fabry patients need comprehensive and interdisciplinary management to stop the progression and functional deterioration of the affected organs by its multiple systemic manifestations. In Latin-American countries, it is difficult to guarantee this comprehensive and coordinated management, due to limited public policies related to orphan diseases diagnosis, treatment and follow up.It is considered crucial to structure support networks specialized in Fabry disease and generate partnerships with health institutions and other health system stakeholders, that would articulate and coordinate patients and relatives counseling and management, establish the specific pharmacological treatment to reduce the progression of the disease and the systemic involvement, deciding between the administration of enzyme replacement therapy or the most recent option of oral management with pharmacological chaperone both with proven effectiveness. This will be the decision of the attending physician, who will propose and advise the therapeutic choice that best suits the patient's needs.

Fabry Disease with Genetic Variants of Unknown Significance and Concomitant Immunoglobulin A Nephropathy

INTRODUCTION

The diagnosis of Fabry disease (FD) with genetic variants of unknown significance (VUSs) is relatively difficult. We explored patients with novel VUS variants and concomitant immunoglobulin A nephropathy (IgAN) to improve the understanding of VUS.

METHODS

The study retrospectively investigated patients with genetically confirmed FD. Probands with VUS were selected from the database of FD patients who underwent genetic analysis. Demographic, clinicopathological, and laboratory data from probands and family members were collected and analyzed.

RESULTS

Fourteen probands and their family members were included in the study. The probands were divided into group 1 (patients with VUS, n = 5) and group 2 (patients with pathologic/likely pathologic variants, n = 9). The group 1 included 2 missense mutations and 1 deletion mutation, while the group 2 included 6 missense mutations and 2 deletion mutations. There were no significant differences in gender, age, serum creatinine, eGFR, and proteinuria between the two groups. IgA deposition with myeloid bodies was found in all VUS patients. The cardiac involvement in group 2 was more severe than that in group 1. Seven families performed the pedigree analysis, and after the comprehensive evaluation, two GLA variants (c.479C>A, p.Ala160Asp; c.1032-1058 del, p.Ser345_Met353del) were upgraded from VUS to the likely pathogenic.

CONCLUSION

The clinical manifestations of FD are heterogeneous. FD often coexists with nephrotic disorders, such as IgAN and MCD. Comprehensive evaluation, especially tissue-specific biopsy, is necessary for patients with GLA-VUSs. Two GLA variants (c.479C>A, p.Ala160Asp; c.1032-1058 del, p.Ser345_Met353del) were upgraded from VUS to the likely pathogenic after the comprehensive evaluation.

Potential Usefulness of Lifetime Globotriaosylsphingosine Exposure at Diagnosis and Baseline Modified Disease Severity Score in Early-Diagnosed Patients With Fabry Disease

BACKGROUND

Fabry disease (FD) is a lysosomal storage disease caused by a deficit of α-galactosidase A (GAL). Recently, plasma globotriaosylsphingosine (lyso-Gb3), a pathogenic analog of a substrate of GAL, has been suggested as a potential biomarker for FD, and disease severity scores, such as the Mainz Severity Score Index (MSSI), the Disease Severity Scoring System (DS3), and FASTEX (FAbry STabilization indEX), are useful tools for evaluating the severity of signs and symptoms in symptomatic FD patients. However, a more useful method of evaluating disease severity in early-diagnosed FD patients such as children, adult females, and asymptomatic patients is needed. Here, we proposed modified MSSI and DS3 scores to which we added phenotype, urinary mulberry bodies, and history of past pain attacks and examined the clinical usefulness of lyso-Gb3 and modified scores for early-diagnosed FD patients.

RESULT

In 13 early-diagnosed FD patients, we developed modified MSSI and DS3 scores and examined the correlation of lifetime lyso-Gb3 exposure at diagnosis with the conventional or modified scores. Lifetime lyso-Gb3 exposure was positively correlated only with the modified DS3 score. Additionally, we examined the long-term changes in plasma lyso-Gb3 concentration and in conventional MSSI, DS3, and FASTEX. In males, plasma lyso-Gb3 concentration decreased more rapidly than in females. In all patients, the severity scores were mild and remained nearly stable throughout the follow-up period.

CONCLUSION

Our data suggest that lifetime lyso-Gb3 exposure and the modified DS3 score are useful in early-diagnosed patients.

A Systematic Literature Review on the Use of Dried Biofluid Microsampling in Patients With Kidney Disease

BACKGROUND

Kidney disease is fairly unique due to the lack of symptoms associated with disease activity, and it is therefore dependent on biological monitoring. Dried biofluids, particularly dried capillary blood spots, are an accessible, easy-to-use technology that have seen increased utility in basic science research over the past decade. However, their use is yet to reach the kidney patient population clinically or in large-scale discovery science initiatives. The aim of this study was to systematically evaluate the existing literature surrounding the use of dried biofluids in kidney research.

METHODS

A systematic literature review was conducted using three search engines and a predefined search term strategy. Results were summarised according to the collection method, type of biofluid, application to kidney disease, cost, sample stability and patient acceptability.

RESULTS

In total, 404 studies were identified and 67 were eligible. In total, 34,739 patients were recruited to these studies with a skew towards male participants (> 73%). The majority of samples were blood, which was used either for monitoring anti-rejection immunosuppressive drug concentrations or for kidney function. Dried biofluids offered significant cost savings to the patient and healthcare service. The majority of patients preferred home microsampling when compared to conventional monitoring.

CONCLUSION

There is an unmet need in bringing dried microsampling technology to advance kidney disease despite its advantages. This technology provides an opportunity to upscale patient recruitment and longitudinal sampling, enhance vein preservation and overcome participation bias in research.

Prevalence of Fabry disease in patients with chronic kidney disease: A systematic review and meta-analysis

Fabry disease (FD) is an X-linked lysosomal storage disease caused by pathogenic variants in the GLA gene. It has a wide range of clinical manifestations, typically related to the specific underlying GLA variant. One of the main features of FD is kidney involvement; therefore, several studies have addressed the prevalence of FD in all types of patients with chronic kidney disease. We performed a systematic review and meta-analysis of screening studies in chronic kidney disease patients, including those on dialysis, had undergone a kidney transplantation, and those who did not receive kidney replacement therapy, and assessed the prevalence of pathogenic variants in these cohorts. Fifty-five studies were included, involving a total of 84,062 individuals. Of these, 251 cases were positive for FD; a third of the reported GLA variants were of a benign phenotype (37.8%), followed by classical phenotype (31.7%), late onset (15.5%), and of uncertain significance (14.7%). The overall prevalence among dialysis patients was 0.10% (CI95%, 0.06-0.15), 0.28% (CI95%, 0.06-0.15) among patients with kidney transplantation, and 0.17% (CI95%, 0.11-0.39) among those without kidney replacement therapy. Although the overall prevalence of FD is low in patients with kidney involvement, screening, especially in patients who have not yet undergone kidney replacement therapy, is important, in order to provide timely and effective treatment interventions, including disease modifying therapies. The prevalence of kidney involvement in females with Fabry Disease is lower but this should not lead to inadequate follow up. Further research is also needed on the impact of genetic variants of uncertain significance to elucidate their role in Fabry disease.

High-risk screening for Fabry disease in hemodialysis patients in Chiba Prefecture, Japan

BACKGROUND

High-risk screening for Fabry disease in dialysis patients is an effective means for reducing the number of undiagnosed cases. However, such screening has not been conducted in Chiba Prefecture, Japan. Herein, we aimed to estimate the prevalence of Fabry disease among patients undergoing hemodialysis in Chiba Prefecture by high-risk screening using α-galactosidase A (αGal A) activity measurement, and examine the hemodialysis effect on αGal A activity.

METHODS

Patients who underwent maintenance hemodialysis at 25 facilities in Chiba Prefecture were recruited. The αGal A activity was measured using the dried blood spot (DBS) test as the first screening. If the enzyme activity was lower than the cut-off, the second screening was performed with the same method before and after dialysis.

RESULTS

Overall, 2924 patients (2036 men and 888 women) were included from which 94 cases (45 men and 48 women) showed decreased αGAL activity in the first screening and 3 (two men and one women) in the second screening. Genetic testing was performed in 3 patients, and the c.1078G > A mutation in GLA gene was detected in one male patient (0.03%). There has been a statistically significant decrease in αGal A activity of DBS at post-dialysis compared to that at pre-dialysis (20.5 ± 10.4 pmol/h/disk and 22.7 ± 11.5 pmol/h/disk, p < 0.0001).

CONCLUSION

The prevalence of Fabry disease among patients undergoing hemodialysis in Chiba Prefecture was estimated as 0.03%. This is the first time that dialysis has been shown to affect the αGal A activity.

Clinical evaluation, accurate diagnosis and treatment of four pedigrees with Fabry's disease

OBJECTIVE

This article analyzes the data of four families with mutations of the GLA (galactosidase) gene with a special focus on the clinical presentation, diagnosis, and interdisciplinary clinical management of Fabry disease (FD) and enzyme replacement therapy (ERT) treatment, and has the aim to assess more accurate prevention and treatment strategy.

METHODS

The MSSI (Mainz Severity Score Index) scale was used to evaluate the clinical data of five children diagnosed in our hospital, and the genotypes of all the patients with FD were collected. Two of the male children started ERT. We summarize the clinical effect and the evaluation of globotriaosylsphingosine (Lyso-GL-3) before and after treatment.

RESULTS

Five children were confirmed as having FD using the family histories, clinical manifestations, α-galactosidase A (a-Gal A) activity, and genetic test results. Two children used agalsidase α every 2 weeks regularly, after ERT. Their clinical symptoms improved, their pain intensity was significantly relieved, and upon re-examination their Lyso-GL-3 decreased conspicuously and no serious adverse reactions occurred. We report for the first time four families with children with FD. The youngest child was only 1 year old. The four families included one girl which is rare in X-linked lysosomal storage diseases.

CONCLUSION

The clinical phenotype of FD in childhood is nonspecific, and the misdiagnosis rate is high. Most children with FD have a delayed diagnosis, and their organs are often seriously damaged in adulthood. Pediatricians must improve their diagnosis and treatment awareness, screen high-risk groups, and emphasize multidisciplinary cooperation and holistic lifestyle management after diagnosis. The diagnosis of the proband is also conducive to the mining of other cases of FD families and has important guiding significance for prenatal diagnosis.

Unexpectedly high renal pathological scores of two female siblings with Fabry disease presenting with urinary mulberry cells without microalbuminuria

We describe the cases of 47- and 45-year-old sisters who were diagnosed with Fabry disease by genomic analysis. Although the only abnormal finding was the presence of mulberry cells in their urinary sediment, the renal pathological scores, which were evaluated by light and electron microscopy, were unexpectedly very high due to severe accumulation of globotriaosylceramide in the glomerular podocytes and tubular epithelial cells. Nephrologists and laboratory technicians should recognize the importance of screening for mulberry cells during urinalysis as this is a simple, inexpensive, and non-invasive method for early diagnosis, leading to early treatment of Fabry disease.

Screening for Fabry disease among male patients on hemodialysis in Awaji Island

BACKGROUND

Fabry disease (FD) manifests decreased α-galactosidase A (α-Gal A) activity and multiorgan damage. There are some undiagnosed cases of the condition among patients on dialysis. The prevalence of FD may also vary with the region.

METHODS

Among 227 male patients undergoing maintenance hemodialysis in Awaji Island, a remote island in Japan, 201 (88.5%) were included in this study. Patients with α-Gal A activity <5.0 pmol/hr/disk proceeded to secondary screening. Patients with positive secondary screening underwent further genetic analysis.

RESULTS

The number of patients with a family history of cardiac, cerebrovascular, and kidney diseases was 31 (15.4%), 23 (11.4%), and 31 (15.4%) patients, respectively. Although three patients (1.5%) had low α-Gal A activity, none of them was positive in the secondary screening.

CONCLUSION

We could not identify any male hemodialysis patient with FD in Awaji Island, even though some patients had a family history of kidney and cardiovascular diseases. This article is protected by copyright. All rights reserved.

High risk population screening for fabry disease in hemodialysis patients in Vojvodina

Introduction. Fabry disease (FD) is an X-linked lysosomal storage disease that develops as a consequence of mutation in the alpha-galactosidase A (GLA) gene. There are more than 1080 known variants in the GLA gene. Some of them are pathogenic, but most of them are benign or represent the genetic change that can be classified as a genetic variant of unknown significance or simply be a representation of genetic polymorphism. There are two main features of FD, classic form and late-onset variants of disease. The main target organs in patients with FD are kidneys, heart and nervous system. Bearing in mind the fact that FD is a rare disease, the best way for active searching of patients is high-risk population screening, after which family screening for every proband case should be performed. Methods. In this paper, we present results of a multicentric pilot study that represents findings from the screening of hemodialysis patients for FD in six hemodialysis units in Vojvodina. Results. We have found one patient with benign mutation and 16 patients with genetic polymorphisms in GLA gene. We have learned that genetic changes in GLA gene can be frequent, but very rarely are of clinical significance and lead to manifestations of FD. Conclusion. Results of this screening study will give us important insights into our future work

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.

Deficiency in the Screening Process of Fabry Disease: Analysis of Chronic Kidney Patients Not on Dialysis

Fabry Disease (FD), a rare and progressive, X-linked lysosomal storage disorder, is caused by mutations in the α-galactosidase A (GLA) gene which leads to enzymatic deficiency of GLA. Misdiagnosed and undiagnosed FD cases are common for the variable FD phenotype, ranging from asymptomatic and/or impairment of single organs, which is typically seen in females and in patients with late-onset mutation, to multiple organ disease, which is frequently found in males with classic GLA mutation. Consequently, for an early diagnosis and an efficient treatment of FD, three different strategies of screening, new-born screening, high-risk screening and familiar screening, have been conducted. However, most of FD screening in the CKD population has been carried out in hemodialysis patients and kidney transplant recipients, for whom the renal damage is already irreversible, so the effectiveness of enzymatic replacement therapy is limited and delayed therapeutic intervention results in worse long-term outcomes. This review investigates the actual strategies of screening initiatives for the identification of FD, examining in detail those performed in CKD patients not on dialysis.

Detection of novel Fabry disease-associated pathogenic variants in Japanese patients by newborn and high-risk screening

BACKGROUND

In Japan, newborn and high-risk screening for Fabry disease (FD), an inherited X-linked disorder caused by GLA mutations, using dried blood spots was initiated in 2006. In newborn screening, 599,711 newborns were screened by December 2018, and 57 newborns from 54 families with 26 FD-associated variants were detected. In high-risk screening, 18,235 individuals who had symptoms and/or a family history of FD were screened by March 2019, and 236 individuals from 143 families with 101 FD-associated variants were detected. Totally 3, 116 variants were detected; 41 of these were not registered in Fabry-database.org or ClinVar and 33 were definitely novel. Herein, we report the clinical outcomes and discuss the pathogenicity of the 41 variants.

METHODS

We traced nine newborns and 46 individuals with the 33 novel variants, and nine newborns and 10 individuals with eight other variants not registered in the FD database, and analyzed the information on symptoms, treatments, and outcomes.

RESULTS

Thirty-eight of the 46 individuals with the 33 novel variants showed symptoms and received enzyme-replacement therapy and/or chaperone treatment.

CONCLUSION

Delayed diagnosis should be avoided in patients with FD. Our results will help clinicians diagnose FD and determine the appropriate treatment for patients with these variants.

Fabry disease screening in high-risk populations in Japan: a nationwide study

Background

Fabry disease (FD) is a X-linked inherited disorder caused by mutations in the GLA gene, which results in the deficiency of α-galactosidase A (α-Gal A). This leads to the progressive accumulation of metabolites, which can cause multisystemic dysfunction. A recent screening study among neonates reported an increase in the incidence of FD, and numerous FD patients remain undiagnosed or even misdiagnosed. Therefore, this study aimed to identify patients with FD by performing high-risk screening in 18,135 individuals, enrolled from October 2006 to March 2019, with renal, cardiac, or neurological manifestations from all prefectures in Japan. A total of 601 hospitals participated in this study.

Results

Low α-Gal A activity was detected in 846 individuals, with 224 of them diagnosed with FD by GLA sequencing. Cases with a family history of FD (n = 64) were also subjected to sequencing, without α-Gal A assay, as per individual request, and 12 of them were diagnosed with a variant of FD. A total of 236 patients with FD (97 males and 139 females) were identified from among 18,199 participants. A total of 101 GLA variants, including 26 novel variants, were detected in the 236 patients with FD from 143 families, with 39 amenable variants (39%) and 79 of the 236 patients (33%) suitable for migalastat treatment.

Conclusions

From among 18,199 participants, 101 GLA variants, including 26 novel variants, were identified in the 236 patients with FD from 143 families. Migalastat was identified as a suitable treatment option in 33% of the patients with FD and 39% of the GLA variants were detected as amenable. Therefore, the simple screening protocol using dried blood spots that was performed in this study could be useful for early diagnosis and selection of appropriate treatments for FD in high-risk and underdiagnosed patients with various renal, cardiac, or neurological manifestations.

Laboratory Diagnosis of Lysosomal Diseases: Newborn Screening to Treatment

The goal of screening programs for inborn errors of metabolism (IEM) is early detection and timely intervention to significantly reduce morbidity, mortality and associated disabilities. Phenylketonuria exemplifies their success as neonates are identified at birth and then promptly treated allowing normal neurological development. Lysosomal diseases comprise about 50 IEM arising from a deficiency in a protein required for proper lysosomal function. Typically, these defects are in lysosomal enzymes with the concomitant accumulation of the enzyme's substrate as the cardinal feature. None of the lysosomal diseases are screened at birth in Australia and in the absence of a family history, traditional laboratory diagnosis of the majority, involves demonstrating a deficiency of the requisite enzyme. Diagnostic confusion can arise from interpretation of the degree of residual enzyme activity causative of disease and is impractical when the disorder is not due to an enzyme deficiency per se. Advances in mass spectrometry technologies has enabled simultaneous measurement of the enzymes' substrates and their metabolites which facilitates the efficiency of diagnosis. Employing urine chemistry as a reflection of multisystemic disease, individual lysosomal diseases can be identified by a characteristic substrate pattern complicit with the enzyme deficiency. Determination of lipids in plasma allows the diagnosis of a further class of lysosomal disorders, the sphingolipids. The ideal goal would be to measure biomarkers for each specific lysosomal disorder in the one mass spectrometry-based platform to achieve a diagnosis. Confirmation of the diagnosis is usually by identifying pathogenic variants in the underlying gene, and although molecular genetic technologies can provide the initial diagnosis, the biochemistry will remain important for interpreting molecular variants of uncertain significance.