The Changing Landscape of Fabry Disease

Fabry disease: a rare disorder calling for personalized medicine

Fabry Disease (FD) is a genetic disease caused by a deficiency in the activity of lysosomal galactosidase A (α-GalA), an enzyme responsible for the catabolism of globotriaosylceramide (Gb3). Since lysosomes are present throughout the body and play a crucial role in catabolism and recycling of cytosolic compounds, FD can affect multiple organs and result in various symptoms, including renal, cardiovascular, neurological, cutaneous, and ophthalmic manifestations. Due to the nonspecific symptoms and the rarity of FD, it is often diagnosed late in life. However, introducing targeted therapies such as enzyme replacement therapy (ERT) and chaperone therapy has significantly improved FD's natural history and prognosis by restoring α-GalA enzyme activity. Despite the advancements, there are limitations to the currently available therapies, which has prompted research into new potential treatments for FD, including alternative forms of enzyme replacement therapy, substrate reduction therapy, mRNA therapy, and genetic therapy. In this review, we analyze the epidemiology, pathophysiology, and treatment of FD, with particular emphasis on promising therapeutic opportunities that could shift the treatment of this rare disease from a standardized to a personalized approach soon.

Outcomes and management of kidney transplant recipients with Fabry disease: a review

Fabry disease is an X-linked inheritable lysosomal storage disease caused by various mutations of the galactosidase α gene resulting in α-galactosidase deficiency. Chronic kidney disease (CKD) is one of the most significant consequences of Fabry disease, with risk of end-stage kidney disease (ESKD) in this population. Like for other patients with ESKD, kidney transplant is the optimal treatment for Fabry disease patients with ESKD. However, enzyme replacement therapy and newer Fabry disease treatments remain important to mitigate other end organ damage such as cardiomyopathy post transplantation. This review is a primer on Fabry disease, which examines the outcomes of disease in the context of kidney transplant prior to, and during, the enzyme replacement treatment era, medical treatment of kidney transplant recipients with Fabry disease, and progress in screening studies.

Fabry-specific treatment in Australia: time to align eligibility criteria with international best practices

BACKGROUND

Disease-specific therapy aims to improve symptoms, stabilise current disease and delay progression in patients with Fabry disease. In Australia, treatment access is subject to eligibility criteria initially established in 2004. Patients and their clinicians question why these criteria have remained unchanged despite significant progress in disease understanding.

AIMS

Appraise the clinical quality of the Australian treatment access criteria.

METHODS

The Fabry Australia Medical Advisory Committee (N = 6) used the Appraisal of Guidelines for REsearch and Evaluation Global Rating Scale (AGREE II GRS) to assess the clinical quality of the current treatment eligibility criteria. They reviewed the literature, developed 17 clinical statements to help guide reforms of the eligibility criteria and achieved consensus (achievement of ≥75% agreement in the range 5-7 on a 7-point Likert scale) through anonymous voting. The findings were applied to develop proposals for revised classification and treatment initiation criteria.

RESULTS

The current treatment eligibility criteria underperformed on the AGREE II GRS. They are pragmatic but out-of-step with contemporary data. Consensus was achieved on all 17 proposed clinical statements. There was strong agreement to differentiate classical male Fabry patients to facilitate timelier access to Fabry-specific treatment. There was also agreement on the value of adopting relevant organ involvement criteria in classical female patients and patients with non-classical disease.

CONCLUSIONS

Australian access criteria are misaligned with current clinical evidence. The clinical statements and proposed classification and initiation criteria should prompt discussions to support more equitable access to treatment and better align Australian practice with contemporary evidence and international guidelines.

Fabry Disease in Women: Genetic Basis, Available Biomarkers, and Clinical Manifestations

Fabry Disease (FD) is a rare lysosomal storage disorder caused by mutations in the GLA gene on the X chromosome, leading to a deficiency in α-galactosidase A (AGAL) enzyme activity. This leads to the accumulation of glycosphingolipids, primarily globotriaosylceramide (Gb3), in vital organs such as the kidneys, heart, and nervous system. While FD was initially considered predominantly affecting males, recent studies have uncovered that heterozygous Fabry women, carrying a single mutated GLA gene, can manifest a wide array of clinical symptoms, challenging the notion of asymptomatic carriers. The mechanisms underlying the diverse clinical manifestations in females remain not fully understood due to X-chromosome inactivation (XCI). XCI also known as "lyonization", involves the random inactivation of one of the two X chromosomes. This process is considered a potential factor influencing phenotypic variation. This review delves into the complex landscape of FD in women, discussing its genetic basis, the available biomarkers, clinical manifestations, and the potential impact of XCI on disease severity. Additionally, it highlights the challenges faced by heterozygous Fabry women, both in terms of their disease burden and interactions with healthcare professionals. Current treatment options, including enzyme replacement therapy, are discussed, along with the need for healthcare providers to be well-informed about FD in women, ultimately contributing to improved patient care and quality of life.

Fabry Disease Nephropathy: Histological Changes With Nonclassical Mutations and Genetic Variants of Unknown Significance

RATIONALE & OBJECTIVE

Fabry disease (FD) is an X-linked genetic disorder that causes lysosomal storage of glycosphingolipids, primarily globotriaosylceramide (Gb3) and its derivative globotriaosylsphingosine (lyso-Gb3), with multiorgan dysfunction including chronic kidney disease. Affected individuals may be carriers of gene variants that are of uncertain significance (GVUS). We describe kidney pathology at the early stages of FD-related kidney disease to gain insights into its association with GVUS and sex.

STUDY DESIGN

Single-center, case series.

SETTING & PARTICIPANTS

Thirty-five consecutively biopsied patients (aged 48.1±15.4 years, 22 females) from among 64 patients with genetically diagnosed FD. Biopsies were retrospectively screened using the International Study Group of Fabry Nephropathy Scoring System.

OBSERVATIONS

Genetic mutation type, p.N215S and D313Y, sex, age, estimated glomerular filtration rate (eGFR), plasma lyso-Gb3 (pLyso-Gb3) levels, and histological parameters, including Gb3 deposits were recorded. Genetic analyses showed mostly missense mutations, p.N215S variant in 15, and the "benign polymorphism" D313Y in 4 of the biopsied patients. Morphological lesions were similar for men and women except for interstitial fibrosis and arteriolar hyalinosis being more common in men. Early in their clinical course, patients with normal/mild albuminuria had podocyte, tubular, and peritubular capillary vacuoles/inclusions, and evidence of chronicity, i.e., glomerulosclerosis, interstitial fibrosis, tubular atrophy. These findings appeared to be associated with pLyso-Gb3, eGFR, and age.

LIMITATIONS

Retrospective design and inclusion of outpatients partially based on family pedigree.

CONCLUSIONS

In early stages of kidney disease in the setting of FD, numerous histological abnormalities are present. These observations suggest that kidney biopsies early in FD may reveal activity of kidney involvement that may inform clinical management.

Prevalence of Kidney and Urinary Tract Complications in Fabry Disease from 2000 to 2020: A Global Cohort Study Including 10,637 Patients

BACKGROUND/AIM

Fabry disease, an X-linked lysosomal storage disorder, causes progressive globotriaosylceramide accumulation in cells throughout the body. Characteristic multiorgan manifestations include renal dysfunction (Fabry nephropathy) and associated urinary tract complications. Enzyme replacement therapy (ERT) has been available since 2001, but contemporary real-world data are lacking regarding Fabry nephropathy risks and treatment outcomes.

PATIENTS AND METHODS

This retrospective cohort study analyzed electronic medical records data for 10,637 Fabry disease patients from the TriNetX research database. Kidney and urinary tract outcomes were evaluated over two decades, 2000-2010 and 2011-2020. Outcomes assessed included chronic kidney disease (CKD), urinary tract infections, urinary incontinence, obstruction, renal insufficiency, and end-stage renal disease (ESRD).

RESULTS

The prevalence of stage 4-5 CKD nearly doubled between 2000-2010 and 2011-2020, while ESRD prevalence rose over 4-fold. Incidence rates showed similar marked elevations across renal and urologic complications. Females and Black patients experienced disproportionate escalations in kidney and urinary tract morbidity.

CONCLUSION

This large cohort study revealed significantly increased Fabry nephropathy and associated urologic complications over the past two decades, contradicting expectations of reduced morbidity with ERT availability. The findings highlight needs to optimize screening, treatment strategies, monitoring practices, and address disparities to curb rising disease burden and improve patient outcomes.

Proteomic analysis unveils Gb3-independent alterations and mitochondrial dysfunction in a gla-/- zebrafish model of Fabry disease

BACKGROUND

Fabry disease (FD) is a rare lysosomal storage disorder caused by mutations in the GLA gene, resulting in reduced or lack of α-galactosidase A activity. This results in the accumulation of globotriaosylceramide (Gb3) and other glycosphingolipids in lysosomes causing cellular impairment and organ failures. While current therapies focus on reversing Gb3 accumulation, they do not address the altered cellular signaling in FD. Therefore, this study aims to explore Gb3-independent mechanisms of kidney damage in Fabry disease and identify potential biomarkers.

METHODS

To investigate these mechanisms, we utilized a zebrafish (ZF) gla-/- mutant (MU) model. ZF naturally lack A4GALT gene and, therefore, cannot synthesize Gb3. We obtained kidney samples from both wild-type (WT) (n = 8) and MU (n = 8) ZF and conducted proteome profiling using untargeted mass spectrometry. Additionally, we examined mitochondria morphology and cristae morphology using electron microscopy. To assess oxidative stress, we measured total antioxidant activity. Finally, immunohistochemistry was conducted on kidney samples to validate specific proteins.

RESULTS

Our proteomics analysis of renal tissues from zebrafish revealed downregulation of lysosome and mitochondrial-related proteins in gla-/- MU renal tissues, while energy-related pathways including carbon, glycolysis, and galactose metabolisms were disturbed. Moreover, we observed abnormal mitochondrial shape, disrupted cristae morphology, altered mitochondrial volume and lower antioxidant activity in gla-/- MU ZF.

CONCLUSIONS

These results suggest that the alterations observed at the proteome and mitochondrial level closely resemble well-known GLA mutation-related alterations in humans. Importantly, they also unveil novel Gb3-independent pathogenic mechanisms in Fabry disease. Understanding these mechanisms could potentially lead to the development of innovative drug screening approaches. Furthermore, the findings pave the way for identifying new clinical targets, offering new avenues for therapeutic interventions in Fabry disease. The zebrafish gla-/- mutant model proves valuable in elucidating these mechanisms and may contribute significantly to advancing our knowledge of this disorder.

An expert consensus on the recommendations for the use of biomarkers in Fabry disease

Fabry disease is an X-linked lysosomal storage disorder caused by the accumulation of glycosphingolipids in various tissues and body fluids, leading to progressive organ damage and life-threatening complications. Phenotypic classification is based on disease progression and severity and can be used to predict outcomes. Patients with a classic Fabry phenotype have little to no residual α-Gal A activity and have widespread organ involvement, whereas patients with a later-onset phenotype have residual α-Gal A activity and disease progression can be limited to a single organ, often the heart. Diagnosis and monitoring of patients with Fabry disease should therefore be individualized, and biomarkers are available to support with this. Disease-specific biomarkers are useful in the diagnosis of Fabry disease; non-disease-specific biomarkers may be useful to assess organ damage. For most biomarkers it can be challenging to prove they translate to differences in the risk of clinical events associated with Fabry disease. Therefore, careful monitoring of treatment outcomes and collection of prospective data in patients are needed. As we deepen our understanding of Fabry disease, it is important to regularly re-evaluate and appraise published evidence relating to biomarkers. In this article, we present the results of a literature review of evidence published between February 2017 and July 2020 on the impact of disease-specific treatment on biomarkers and provide an expert consensus on clinical recommendations for the use of those biomarkers.

CRISPR/Cas9-mediated A4GALT suppression rescues Fabry disease phenotypes in a kidney organoid model

The objective of this study was to investigate whether CRISPR/Cas9-mediated suppression of A4GALT could rescue phenotype of Fabry disease nephropathy (FDN) using human induced pluripotent stem cells (hiPSCs) derived kidney organoid system. We generated FDN patient-derived hiPSC (CMC-Fb-002) and FD-specific hiPSCs (GLA-KO) by knock-out (KO) of GLA in wild-type (WT) hiPSCs using CRISPR/Cas9. We then performed A4GALT KO in both CMC-Fb-002 and GLA-KO to make Fb-002-A4GALT-KO and GLA/A4GALT-KO, respectively. Using these hiPSCs, we generated kidney organoids and compared alpha-galactosidase-A enzyme (α-GalA) activity, globotriaosylceramide (Gb-3) deposition, and zebra body formation under electron microscopy (EM). We also compared mRNA expression levels using RNA-seq and qPCR. Generated hiPSCs showed typical pluripotency markers without chromosomal disruption. Expression levels of GLA in CMC-Fb-002 and GLA-KO and expression levels of A4GALT in Fb-002-A4GALT-KO and GLA/A4GALT-KO were successfully decreased compared to those in WT-hiPSCs, respectively. Generated kidney organoids using these hiPSCs expressed typical nephron markers. In CMC-Fb-002 and GLA-KO organoids, α-GalA activity was significantly decreased along with increased deposition of Gb-3 in comparison with WT organoids. Intralysosomal inclusion body was also detected under EM. However, these disease phenotypes were rescued by KO of A4GALT in both GLA/A4GALT-KO and Fb-002-A4GALT-KO kidney organoids. RNA-seq showed increased expression levels of genes related to FDN progression in both GLA-mutant organoids compared to those in WT. Such increases were rescued in GLA/A4GALT-KO or Fb-002-A4GALT-KO organoids. CRISPR/Cas9 mediated suppression of A4GALT could rescue FDN phenotype. Hence, it can be proposed as a therapeutic approach to treat FDN.

Gastrointestinal Manifestations and Low-FODMAP Protocol in a Cohort of Fabry Disease Adult Patients

Fabry disease (FD) is an X-linked lysosomal disorder caused by α-galactosidase A enzyme deficiency. Gastrointestinal (GI) manifestations are reported in FD with a prevalence of about 50%, usually treated by Enzymatic Replacement Therapy (ERT) or oral treatment. Since FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) can be involved in GI manifestations and dysbiosis in FD patients, a low-FODMAP diet could represent an alternative adjunctive treatment in FD subjects, as well as being useful for reducing symptoms in Irritable Bowel Syndrome (IBS). We retrospectively assessed data from 36 adult FD patients followed at the Inherited Metabolic Rare Diseases Adult Centre of the University Hospital of Padova (mean age 47.6 ± 16.2 years). Patients were screened for GI symptoms by IBS severity score and Gastrointestinal Symptom Rating Scale (GSRS) questionnaires. In symptomatic patients, the low-FODMAP diet was proposed in order to improve GI manifestations; it consists of a phase of elimination of fermentable saccharides, succeeded by a gradual reintegration of the same. Severe or moderate GI symptoms were found in 61.1% of patients, with no correlation to the therapy in use, and significantly more severe in the classical form of FD. The protocol was completed by seven patients affected by severe GI manifestations, significantly higher than the others. The low-FODMAP diet significantly improved indigestion, diarrhoea, and constipation. This dietetic protocol seemed to have a positive impact on intestinal symptoms, by identifying and reducing the intake of the foods most related to the onset of disorders and improving the clinical manifestations. A low-FODMAP diet may be an effective alternative approach to improve intestinal manifestations and quality of life, and nutrition can play an important role in the multidisciplinary care of patients with FD.

Gene Expression Analysis in gla-Mutant Zebrafish Reveals Enhanced Ca2+ Signaling Similar to Fabry Disease

Fabry disease (FD) is an X-linked inborn metabolic disorder due to partial or complete lysosomal α-galactosidase A deficiency. FD is characterized by progressive renal insufficiency and cardio- and cerebrovascular involvement. Restricted access on Gb3-independent tissue injury experimental models has limited the understanding of FD pathophysiology and delayed the development of new therapies. Accumulating glycosphingolipids, mainly Gb3 and lysoGb3, are Fabry specific markers used in clinical follow up. However, recent studies suggest there is a need for additional markers to monitor FD clinical course or response to treatment. We used a gla-knockout zebrafish (ZF) to investigate alternative biomarkers in Gb3-free-conditions. RNA sequencing was used to identify transcriptomic signatures in kidney tissues discriminating gla-mutant (M) from wild type (WT) ZF. Gene Ontology (GO) and KEGG pathways analysis showed upregulation of immune system activation and downregulation of oxidative phosphorylation pathways in kidneys from M ZF. In addition, upregulation of the Ca²⁺ signaling pathway was also detectable in M ZF kidneys. Importantly, disruption of mitochondrial and lysosome-related pathways observed in M ZF was validated by immunohistochemistry. Thus, this ZF model expands the pathophysiological understanding of FD, the Gb3-independent effects of gla mutations could be used to explore new therapeutic targets for FD.

IgA nephropathy with mimicking Fabry disease: A case report and literature review

BACKGROUND

Fabry disease (FD) is a rare, inherited disease lysosomal storage disorder caused by the lack of an alpha-galactosidase enzyme. This genetic disease can affect both men and women. The understanding of FD is very important as this condition can be effectively treated. For women who may exhibit normal residual enzyme activity, the diagnosis is more challenging.

CASE PRESENTATION

Herein, we reported on a case of IgA nephropathy and renal disease that mimicked FD in a female patient. The presence of zebra bodies in the cytoplasm of glomerular podocytes is widely accepted as a hallmark pathological manifestation of FD. In the present case, renal biopsy analysis revealed the presence of zebra bodies; however, genetic testing indicated that the patient did not have FD. The mechanisms and causes of zebra body formation remained unclear in the present case. However, the patient responded well to treatment with an angiotensin receptor blocker.

CONCLUSIONS

The reported findings can be useful for the differential diagnosis of FD and renal diseases in the future. Our results also highlight the clinical significance of zebra bodies in renal disease.

The Impact of Kidney Biopsy for Fabry Nephropathy Evaluation on Patients’ Management and Long-Term Outcomes: Experience of a Single Center

Background: Fabry disease (FD) is a rare lysosomal storage disease causing progressive loss of target organ function. All renal cell types are involved from the early stages, even before clinical signs can be detected. FD-specific therapies can stop/mitigate disease progression. Thus, it is important to validate early markers of renal lesions so that they can be adopted as criteria for timely treatment initiation. Materials and methods: We retrospectively analyzed and extensively evaluated 21 FD case patients; this evaluation included a kidney biopsy. We looked for the influence of pathological findings on the management of FD patients. In addition, we investigated the association between general and FD-specific features and long-term patients’ outcomes. We defined a combined endpoint as being at least one of the following: 50% decrease of estimated glomerular filtration rate (eGFR) from baseline, kidney failure (KF), end-stage kidney disease (ESKD), or death and mortality. Results: Our cohort of 21 FD patients (11 males and 10 females) was stratified according to the presence of the combined endpoint: group 1 (n = 15) included patients without the combined endpoint, while group 2 (n = 6) patients reached the combined endpoint outcome. Patients from group 2 presented lower mean baseline eGFR (72.2 ± 38.7 mL/min/1.73 m² vs. 82.5 ± 26.4 mL/min/1.73 m²) without statistical significance (p = 0.44), but significantly (p = 0.22) higher median baseline proteinuria (2.7 g/24 h vs. 0.4 g/24 h). Specific lysosomal deposits were identified in all patients. Segmental sclerosis was present in all patients with the combined endpoint and in only 33% of patients without the combined endpoint (p = 0.009). Global sclerosis and interstitial fibrosis were present in both groups, with no significant differences. A total of 15 out of the 16 treatment-naïve patients (7 males and 9 females) started FD-specific therapy after kidney biopsy. Treatment was initiated in all male FD patients and in 8 female patients. In 2 females, pathological findings in kidney biopsy offered important reasons to start FD treatment, although specific criteria of the Romanian protocol for prescription of FD-specific therapy were still not fulfilled. Cox univariate analysis showed that every increase in 24 h proteinuria with 1 g is associated with a 65% risk of developing the combined endpoint (HR = 1.65; 95%CI: 1.05–2.58; p = 0.02), and that the presence of segmental sclerosis increased the risk of developing the combined endpoint by 51.3 times (HR = 51.3; 95% CI: 95% CI: 1.67–103.5; p = 0.01). Kaplan–Meier analysis showed that the cumulative risk of developing the combined endpoint was higher in patients in whom segmental sclerosis (100% vs. 0%, log-rank test, p = 0.03) was present. Conclusions: Histological evaluation is an important tool for the detection of early kidney involvement and provides additional support to the early initiation of FD-specific therapy. Presence of segmental sclerosis can predict the long-term outcomes of kidney disease deterioration and mortality and may be used as an early indicator of disease progression. Additionally, in the absence of other criteria according to current guidelines, specific FD renal lesions as revealed by kidney biopsy might become a distinct criterion to initiate FD therapy.

The potential consequences of bidirectional promoter methylation on GLA and HNRNPH2 expression in Fabry disease phenotypes in a family of patients carrying a GLA deletion variant

Fabry disease (FD) is a rare inherited disease characterized by a wide range of symptoms attributed to GLA mutations resulting in defective α-galactosidase A (α-Gal A) and accumulation of glycosphingolipids. The GLA locus is paired in a divergent manner with the heterogeneous nuclear ribonucleoprotein HNRNPH2 locus mapped in the RPL36A-HNRNPH2 readthrough locus. As a follow-up to our recent finding of the co-regulation of GLA and HNRNPH2 via a bidirectional promoter (BDP) in normal kidney and skin cells, the potential accumulative influence of BDP methylation and GLA mutation on the severity of FD in patients from the same family, two males and two females carrying a GLA deletion mutation, c.1033_1034delTC (p.Ser345Argfs) was addressed in the present study. The molecular analyses of the FD patients compared with the control revealed that the expression of GLA was significantly low (P<0.05), and HNRNPH2 showed a tendency of low expression (P=0.1) when BDP methylation was elevated in FD patients, compared with low BDP methylation and high GLA expression (P<0.05), and a high trend of HNRNPH2 expression in normal individuals. The accumulative effects of the mutation and BDP methylation with the severity of the disease were observed in three patients. One male FD patient, a member of the FD family diagnosed with progressive loss of kidney function, hypertension, and eventually a stroke, and the lowest level of α-Gal A enzyme activity showed the highest BDP DNA methylation level. It is concluded that the DNA methylation of GLA-HNRNPH2 BDP may serve a role in diagnosing and treating FD.

The 30-year Natural History of Non-classic Fabry Disease with an R112H Mutation

Fabry disease is a rare X-linked lysosomal storage disorder caused by mutations in the alpha-galactosidase A (GLA) gene that results in deficiency of the enzyme GLA and leads to the accumulation of globotriaosylceramide (GL-3) in cells. The accumulation of GL-3 may lead to life-threatening complications. Significant advances in genetic sequencing technology have led to a better understanding of genotype-phenotype interactions in Fabry disease. Fabry disease with an R112H mutation is known as the non-classic type. However, the long-term clinical course of the disease remains unknown. We herein report a patient with a 30-year natural history of non-classic Fabry disease with an R112H mutation.

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.

Hearing loss in inherited metabolic disorders: A systematic review

Inherited metabolic disorders (IMDs) have been observed in individuals with hearing loss (HL), but IMDs are rarely the cause of syndromic HL. With early diagnosis, management of HL is more effective and cortical reorganization is possible with hearing aids or cochlear implants. This review describes relationships between IMDs and HL in terms of incidence, etiology of HL, pathophysiology, and treatment. Forty types of IMDs are described in the literature, mainly in case reports. Management and prognosis are noted where existing. We also describe IMDs with HL given age of occurrence of HL. Reviewing the main IMDs that are associated with HL may provide an additional clinical tool with which to better diagnose syndromic HL.

Levels of Lyso GL-1 in Gaucher and Lyso GL-3 in Fabry patients from India: Diagnostic aids for these lysosomal storage disorders

BACKGROUND & AIMS

Lysosomal storage disorders (LSDs) remain a significant cause of morbidity in the Indian population and treatment is largely out of reach for most patients. Although data on enzymatic and molecular diagnosis of Gaucher disease (GD) and Fabry disease (FD) in Indian patients are available, the present study intended to establish the pathogenic levels of Lyso GL-1 and Lyso GL-3 in patients of GD and FD respectively as diagnostic aids.

MATERIALS AND METHODS

From 2017 to 2019, ninety confirmed Gaucher cases (by enzymatic and molecular analysis) were tested for chitotriosidase (fluorometrically) and Lyso GL-1 (LC-MS/MS) and ten confirmed Fabry cases were analyzed for Lyso GL-3 (LC-MS/MS).

RESULTS

Lyso GL-1 (median: 685.5 ng/mL, cut-off: 14) and Lyso GL-3 (median: 75.6 ng/mL, cut-off: 3.5) were found to be elevated in all enzymatically deficient patients of GD and FD respectively, however, no specific trend was observed between the levels of these biomarkers and the pathogenic variant(s) present in the patients of these disorders.

CONCLUSIONS

This is the first report on Lyso GL-1 and Lyso GL-3 levels in Indian patients of GD and FD respectively. These results will be useful for early diagnosis to improve management of these LSDs.

Elevated Ambulatory Blood Pressure Measurements are Associated with a Progressive Form of Fabry Disease

 INTRODUCTION: Published data on hypertension incidence and management in Anderson-Fabry disease are scant and the contribution of elevated blood pressure to organ damage is not well recognized.

AIM

Therefore, we have assessed blood pressure values and their possible correlations with clinical findings in a well described cohort of Fabry patients.

METHODS

Between January 2015 and May 2019, all adult Fabry patients (n = 24 females, n = 8 males) referred to our institute were prospectively enrolled. During the first examination patient's genotype and clinical characteristics were recorded. Blood pressure data were obtained by standard observed office measurements followed, within 6 months, by ambulatory blood pressure monitoring and home self-recordings. Organ involvement, including kidneys, heart and brain, was monitored over time. Consequently, patients were defined as clinically stable or progressive through the Fabry Stabilization Index.

RESULTS

The standard office measurements have diagnosed hypertension in three (9.37%) patients, but the ambulatory monitoring showed elevated blood pressure in six (18.75%) patients, revealing three cases of masked hypertension. All the hypertensive patients were females and, compared with normotensive subjects, they presented a lower glomerular filtration rate (p < 0.05) and a more advanced cardiac hypertrophy (p < 0.05). Four (66.7%) of them were diagnosed with a progressive form of the disease through the Fabry Stabilization Index while the majority of the normotensive group (84.6%, n = 19) was stable over time. No correlation was found between the prevalence of hypertension and the type of mutations causing Fabry disease.

CONCLUSION

Hypertension can be found in a restricted portion of clinically stable Fabry patients. In contrast, patients presenting with a progressive organ involvement, particularly renal impairment, have a major risk of developing uncontrolled blood pressure, and should be followed carefully. Moreover, the ambulatory blood pressure monitoring proved to be useful to reveal masked hypertension, which can contribute to the progressive worsening of the organ damage. Therefore, a proper diagnosis and therapy of hypertension may improve the outcome of Fabry patients.

Fabry Disease: Molecular Basis, Pathophysiology, Diagnostics and Potential Therapeutic Directions

Fabry disease (FD) is a lysosomal storage disorder (LSD) characterized by the deficiency of α-galactosidase A (α-GalA) and the consequent accumulation of toxic metabolites such as globotriaosylceramide (Gb3) and globotriaosylsphingosine (lysoGb3). Early diagnosis and appropriate timely treatment of FD patients are crucial to prevent tissue damage and organ failure which no treatment can reverse. LSDs might profit from four main therapeutic strategies, but hitherto there is no cure. Among the therapeutic possibilities are intravenous administered enzyme replacement therapy (ERT), oral pharmacological chaperone therapy (PCT) or enzyme stabilizers, substrate reduction therapy (SRT) and the more recent gene/RNA therapy. Unfortunately, FD patients can only benefit from ERT and, since 2016, PCT, both always combined with supportive adjunctive and preventive therapies to clinically manage FD-related chronic renal, cardiac and neurological complications. Gene therapy for FD is currently studied and further strategies such as substrate reduction therapy (SRT) and novel PCTs are under investigation. In this review, we discuss the molecular basis of FD, the pathophysiology and diagnostic procedures, together with the current treatments and potential therapeutic avenues that FD patients could benefit from in the future.

Proteomics for the study of new biomarkers in Fabry disease: State of the art

Nephropathy represents a major complication of Fabry Disease and its accurate characterization is of paramount importance in predicting the disease progression and assessing the therapeutic responses. The diagnostic process still relies on performing renal biopsy, nevertheless many efforts have been made to discover early reliable biomarkers allowing us to avoid invasive procedures. In this field, proteomics offers a sensitive and fast method leading to an accurate detection of specific pathological proteins and the discovery of diagnostic and prognostic biomarkers that reflect disease progression and facilitate the evaluation of therapeutic responses. Here, we report a review of selected literature focusing on the investigation of several proteomic techniques highlighting their advantages, limitations and future perspectives in their application in the routine study of Fabry Nephropathy.

Renal Manifestations of Fabry Disease: A Narrative Review

Purpose of review

In this narrative review, we describe general aspects, histological alterations, treatment, and implications of Fabry disease (FD) nephropathy. This information should be used to guide physicians and patients in a shared decision-making process.

Source of information

Original peer-reviewed articles, review articles, and opinion pieces were identified from PubMed and Google Scholar databases. Only sources in English were accessed.

Methods

We performed a focused narrative review assessing the main aspects of FD nephropathy. The literature was critically analyzed from a theoretical and contextual perspective, and thematic analysis was performed.

Key findings

FD nephropathy is related to the progressive accumulation of GL3, which occurs in all types of renal cells. It is more prominent in podocytes, which seem to play an important role in the pathogenesis of this nephropathy. A precise detection of renal disorders is of fundamental importance because the specific treatment of FD is usually delayed, making reversibility unlikely and leading to a worse prognosis.

Limitations

As no formal tool was applied to assess the quality of the included studies, selection bias may have occurred. Nonetheless, we have attempted to provide a comprehensive review on the topic using current studies from experts in FD and extensive review of the literature.

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.

Screening for Fabry Disease in Kidney Transplant Recipients: Experience of a Multidisciplinary Team

Fabry disease (FD) is a rare cause of end-stage renal disease requiring kidney transplantation. Data on the incidence of unrecognized FD in kidney transplant recipients are scarce and probably underestimated. This study evaluated the incidence of FD in a population of kidney recipients, with a particular focus of the multidisciplinary approach for an early clinical assessment and therapeutic approach. Two hundred sixty-five kidney transplant recipients were screened with a genetic analysis for α-galactosidase A (GLA) mutation, with measurement of α-Gal A enzyme activity and Lyso Gb3 levels. Screening was also extended to relatives of affected patients. Seven patients (2.6%) had a GLA mutation. Two patients had a classic form of FD with Fabry nephropathy. Among the relatives, 15 subjects had a GLA mutation, and two had a Fabry nephropathy. The clinical and diagnostic assessment was completed after a median of 3.2 months, and mean time from diagnosis to treatment was 4.6 months. This study reported a high incidence of unrecognized GLA mutations in kidney transplant recipients. Evaluation and management by a multidisciplinary team allowed for an early diagnosis and treatment, and this would result in a delay in the progression of the disease and, finally, in better long-term outcomes.

Screening for Fabry Disease in Kidney Transplant Recipients: Experience of a Multidisciplinary Team

Fabry disease (FD) is a rare cause of end-stage renal disease requiring kidney transplantation. Data on the incidence of unrecognized FD in kidney transplant recipients are scarce and probably underestimated. This study evaluated the incidence of FD in a population of kidney recipients, with a particular focus of the multidisciplinary approach for an early clinical assessment and therapeutic approach. Two hundred sixty-five kidney transplant recipients were screened with a genetic analysis for α-galactosidase A (GLA) mutation, with measurement of α-Gal A enzyme activity and Lyso Gb3 levels. Screening was also extended to relatives of affected patients. Seven patients (2.6%) had a GLA mutation. Two patients had a classic form of FD with Fabry nephropathy. Among the relatives, 15 subjects had a GLA mutation, and two had a Fabry nephropathy. The clinical and diagnostic assessment was completed after a median of 3.2 months, and mean time from diagnosis to treatment was 4.6 months. This study reported a high incidence of unrecognized GLA mutations in kidney transplant recipients. Evaluation and management by a multidisciplinary team allowed for an early diagnosis and treatment, and this would result in a delay in the progression of the disease and, finally, in better long-term outcomes.