Manifestations of Fabry disease in placental tissue

Inflammation, Oxidative Stress, and Endothelial Dysfunction in the Pathogenesis of Vascular Damage: Unraveling Novel Cardiovascular Risk Factors in Fabry Disease

Anderson-Fabry disease (AFD), a genetic disorder caused by mutations in the α-galactosidase-A (GLA) gene, disrupts lysosomal function, leading to vascular complications. The accumulation of globotriaosylceramide (Gb3) in arterial walls triggers upregulation of adhesion molecules, decreases endothelial nitric oxide synthesis, and induces reactive oxygen species production. This cascade results in fibrotic thickening, endothelial dysfunction, hypercontractility, vasospasm, and a pro-thrombotic phenotype. AFD patients display increased intima-media thickness (IMT) and reduced flow-mediated dilation (FMD), indicating heightened cardiovascular risk. Nailfold capillaroscopy (NFC) shows promise in diagnosing and monitoring microcirculatory disorders in AFD, though it remains underexplored. Morphological evidence of AFD as a storage disorder can be demonstrated through electron microscopy and immunodetection of Gb3. Secondary pathophysiological disturbances at cellular, tissue, and organ levels contribute to the clinical manifestations, with prominent lysosomal inclusions observed in vascular, cardiac, renal, and neuronal cells. Chronic accumulation of Gb3 represents a state of ongoing toxicity, leading to increased cell turnover, particularly in vascular endothelial cells. AFD-related vascular pathology includes increased renin-angiotensin system activation, endothelial dysfunction, and smooth muscle cell proliferation, resulting in IMT increase. Furthermore, microvascular alterations, such as atypical capillaries observed through NFC, suggest early microvascular involvement. This review aims to unravel the complex interplay between inflammation, oxidative stress, and endothelial dysfunction in AFD, highlighting the potential connections between metabolic disturbances, oxidative stress, inflammation, and fibrosis in vascular and cardiac complications. By exploring novel cardiovascular risk factors and potential diagnostic tools, we can advance our understanding of these mechanisms, which extend beyond sphingolipid accumulation to include other significant contributors to disease pathogenesis. This comprehensive approach can pave the way for innovative therapeutic strategies and improved patient outcomes.

Use of T1 mapping in cardiac MRI for the follow-up of Fabry disease in a pediatric population

Background

Fabry disease (FD) is a rare X-linked lysosomal disorder caused by pathogenic variants in the alpha-galactosidase-A gene (GLA). Life threatening complications in adulthood include chronic kidney failure, strokes and the cardiac involvement which is the leading cause of mortality. Usually, it presents with hypertrophic cardiomyopathy, together with arrhythmia and conduction abnormalities. An early indicator is decreased T1 value on cardiac magnetic resonance (CMR). Enzyme replacement therapy (ERT) is effective on some extra-cardiac symptoms but its effect on cardiac lesions depends on the level of initial myocardial lesions. CMR is routinely used to monitor cardiac involvement in FD due to its capacity for tissular characterization. However, there is a lack of data on the pediatric population to understand how to integrate CMR into early therapeutic decisions.

Method

Monocentric longitudinal study carried out at Montpellier University Hospital from 2016 to 2022. All pediatric patients with FD were evaluated over time with clinical, biological, and cardiac imaging (CMR, echocardiography).

Results

Out of the six patients included, (3 males), five were treated with ERT during the study. Low T1 values were observed in 4 patients. The normalization of T1 values was observed after 4 years of ERT in 3 patients.

Conclusion

Due to the lack of strong clinical and biological markers of FD in pediatric patients, initiation and follow-up of ERT efficacy remain challenging. CMR with T1-mapping, a noninvasive method, could play a role in the evaluation of early cardiac impairment in young patients at diagnosis and during follow-up with or without ERT.

Impact of kidney biopsy on deciding when to initiate enzyme replacement therapy in children with Fabry disease

BACKGROUND

Recommendations on when to start enzyme replacement therapy (ERT) in children with Fabry disease (FD) differ between guidelines. In this study, kidney biopsies of a cohort of 14 untreated children and one treated child were analyzed for their morphologic changes to determine whether early initiation of ERT is indicated.

METHODS

All pediatric FD patients (< 18 years old) diagnosed between 2003 and 2021 in our department who received a kidney biopsy were enrolled. Clinical symptoms; laboratory parameters regarding kidney function, such as eGFR, plasma urea, protein-creatinine, and albumin/creatinine ratio; and 14 kidney biopsies prior to ERT and one under treatment were retrospectively analyzed.

RESULTS

A total of 14 patients were enrolled, including 9 male and 5 female children, aged 3-18 years (median age 11). Seven of the enrolled children were 10 years old or younger. Histological analysis of kidney biopsy samples revealed severe vacuolization and accumulation of inclusions in podocytes and renal tubules. The majority of cases had no FD-specific clinical or laboratory features independent of age, gender, or genotype. The youngest FD patient presenting with isolated abnormal kidney biopsy was 3 years old.

CONCLUSIONS

We demonstrate that histological lesions, typical for FD, can be observed in kidney biopsies at a very young age in patients without classical clinical symptoms or laboratory abnormalities. Thus, we recommend kidney biopsies as a possible tool for early diagnosis of renal involvement in FD. As a consequence of these early biopsy findings without a clinical correlate, an early initiation of ERT should be considered. A higher resolution version of the Graphical abstract is available as Supplementary information.

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.

[Multisystem lesions in orphan diseases: rheumatological aspects of Fabry's disease. Case report]

Fabry-Andersen disease is a genetically determined, progressive disease related to lysosomal storage diseases, linked to the X chromosome, characterized by impaired glycosphingolipid metabolism, due to the deficiency or absence of the enzyme α-galactosidase A. Fabry disease is a multisystem disease and is characterized by damage to vital organs - kidneys, heart, brain, with the occurrence of complications that cause an unfavorable prognosis. Autoinflammation mechanisms with signs of chronic inflammation are involved in the pathogenesis of the disease. One of the features of Fabry disease are clinical manifestations in the form of arthralgia, fever, skin lesions, which are similar to rheumatological diseases. The article presents a clinical observation of the classical type of Fabry disease with multiple organ manifestation, which required differential diagnosis with rheumatological diseases. Rheumatologists are specialists who are involved in the early diagnosis of Fabry disease, so they should have a high awareness of this sphingolipidosis.

Ophthalmic Manifestations in Fabry Disease: Updated Review

Fabry disease (FD) is an X-linked lysosomal storage disorder, causing Gb-3 (globotriaosylceramide) buildup in cellular lysosomes throughout the body, in particular in blood vessel walls, neuronal cells, and smooth muscle. The gradual accumulation of this glycosphingolipid in numerous eye tissues causes conjunctival vascular abnormalities, corneal epithelial opacities (cornea verticillata), lens opacities, and retinal vascular abnormalities. Although a severe vision impairment is rare, these abnormalities are diagnostic indicators and prognostics for severity. Cornea verticillata is the most common ophthalmic feature in both hemizygous men and heterozygous females. Vessel tortuosity has been linked to a faster disease progression and may be useful in predicting systemic involvement. New technologies such as optical coherence tomography angiography (OCTA) are useful for monitoring retinal microvasculature alterations in FD patients. Along with OCTA, corneal topographic analysis, confocal microscopy, and electro-functional examinations, contributed to the recognition of ocular abnormalities and have been correlated with systemic involvement. We offer an update regarding FD ocular manifestations, focusing on findings derived from the most recent imaging modalities, to optimize the management of this pathology.

Cardiac magnetic resonance in Fabry disease

Fabry disease (FD) is a rare X-linked inherited lysosomal storage disorder caused by deficient a-galactosidase A activity that leads to an accumulation of glycolipids, mainly globotriaosylceramide (Gb3) and globotriaosylsphingosine, in affected tissues, including the heart. Cardiovascular involvement usually manifests as left ventricular hypertrophy (LVH), myocardial fibrosis, heart failure, and arrhythmias, which limit the quality of life and represent the most common causes of death. Following the introduction of enzyme replacement therapy, early diagnosis and treatment have become essential in slowing down the disease progression and preventing major cardiac complications. Recent advances in the understanding of FD pathophysiology suggest that in addition to Gb3 accumulation, other mechanisms contribute to the development of cardiac damage. FD cardiomyopathy is characterized by an earlier stage of glycosphingolipid accumulation and a later one of hypertrophy. Morphological and functional aspects are not specific in the echocardiographic evaluation of Anderson-Fabry disease. Cardiac magnetic resonance with tissue characterization capability is an accurate technique for the differential diagnosis of LVH. Progress in imaging techniques has improved the diagnosis and staging of FD-related cardiac disease: a decreased myocardial T1 value is specific of FD. Late gadolinium enhancement is typical of the later stage of cardiac involvement but as in other cardiomyopathy is also valuable to predict the outcome and cardiac response to therapy.

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.

Aseptic meningitis in Fabry disease due to a novel GLA variant: an expanded phenotype?

BACKGROUND

F abry disease (FD) is an X-linked lysosomal storage disorder with accumulation of globotriosylceramide, causing neurologic involvement mainly as acroparesthesias and cerebrovascular disease. Aseptic meningitis has been reported in 11 patients with FD, but no prior study has correlated alpha-galactosidase (GLA) specific variants with meningitis. We present in this manuscript a family in which a novel GLA pathogenic variant was associated with aseptic meningitis in 2 of 5 family members.

METHODS

This study began with identifying the proband, then screening family members for FD symptoms and evaluating symptomatic individuals for genetic and biochemical status. All patients underwent magnetic resonance imaging, and those with headache underwent cerebrospinal fluid (CSF) analysis.

RESULTS

Five patients (3 females) from a single family were included in this study. Mean age at diagnosis was 20.6 years. Two patients (40%) had aseptic meningitis; one of them also had cerebrovascular events. C-reactive protein and erythrocyte sedimentation rate were elevated during aseptic meningitis episodes. Both patients responded to intravenous methylprednisolone with resolution of fever, headache, and vomiting. One of them recurred and needed chronic immunosuppression with azathioprine.

CONCLUSION

We described aseptic meningitis in a family with a novel GLA variant. Meningitis might be a common phenomenon in FD and not a particularity of this variant. Understanding the mechanisms underlying meningitis and its association with cerebrovascular events may lead to a new paradigm of treatment for stroke in these patients. Further prospective studies with CSF collection in patients with FD and recurrent headache could help to elucidate this question.

Determining the etiology of cerebral stroke: from the most prevalent to rare causes

Cerebral stroke remains the leading cause of death and disability worldwide as well as in Ukraine. After a cerebral stroke, there is an increased risk of a new cerebral stroke (9‒15 % within 1 year), and about a quarter of all cerebral stroke are recurrent. Up to 80 % of recurrent cerebral stroke can be avoided through lifestyle modifications (healthy diet, sufficient amount of physical activity, normalization of body weight, cessation of smoking and alcohol abuse) and control of chronic diseases such as hypertension, diabetes, hyperlipidemia and atrial fibrillation. The key to effective secondary prevention is determining the etiology of cerebral stroke, which requires a primary examination in all cases and a number of additional tests as needed. The most common causes of ischemic cerebral stroke are cardiogenic embolism, atherosclerosis of the large cerebral arteries (macroangiopathy), and brain small vessels disease (microangiopathy), but approximately 1/3 of cerebral stroke have other, rear, determined cause or the cause remains unknown despite the appropriate workup (cryptogenic cerebral stroke). In the review, we discuss modern approaches to ischemic cerebral stroke classification and determination of their etiology, from the most prevalent to the rarest causes. A careful search for the cause of cerebral stroke is particularly important in young patients (aged 18 to 50 years) with a high life expectancy. We have reviewed in detail the possibilities of screening for subclinical atrial fibrillation by long-term cardiac monitoring with implantable devices and the diagnosis of monogenetic causes of cerebral stroke, with a particular focus on Fabry disease, for which there is an effective treatment.

Characterization of pregnancy outcome of women with an offspring with inborn errors of metabolism: A population-based study

Introduction: Inborn errors of metabolism (IEM) are scarce, and their diagnosis is often made after birth. This has led to the perception that most fetuses affected by these disorders do not become clinically apparent during pregnancy. Our aim was to determine the obstetrical characteristics of women with an offspring affected by IEM.

Methods: This population-based retrospective cohort study included all women who delivered at the Soroka University Medical Center (SUMC) from 1988 to 2017 who met the inclusion criteria. Mothers who had an offspring with IEM were included in the study group, and those who had offsprings without IEM comprised the comparison group.

Results: A total of 388,813 pregnancies were included in the study, and 184 of them were complicated by a fetus with IEM. The number of Bedouin women was higher in the IEM-affected infant group than in the comparison group (90.8% vs. 53.3%, p &lt; 0.001); women who had a fetus with IEM had a higher rate of polyhydramnios (7.1% vs. 3.2%, p = 0.005), HELLP syndrome (3.3% vs. 1.1%, p = 0.014), and preterm birth (20.7% vs. 10.1%, p &lt; 0.001); neonates with IEM had lower mean birth weight (p &lt; 0.001), lower Apgar scores at 1′ and 5′ minutes (p &lt; 0.001), and a higher rate of fetal growth restriction (FGR) (p &lt; 0.001), postpartum death &lt;28 days (p &lt; 0.001), and neonatal death (p &lt; 0.001) than those in the comparison group. Pregnancies with IEM fetuses were independently associated with preterm birth (OR 2.00; CI 1.4–3), polyhydramnios (OR 2.08; CI 1.17–3.71), and FGR (OR 2.24; CI 1.2–4.19). Each family of metabolic diseases is independently associated with specific pregnancy complications (i.e., mitochondrial diseases are associated with HELLP syndrome (OR 5.6; CI 1.8–17), and lysosomal storage disease are associated with nonimmune hydrops fetalis (OR 26.4; CI 3.39–206).

Conclusion: This study reports for the first time, an independent association of IEM with specific complications of pregnancy. This observation has clinical implications, as the identification of specific pregnancy complications in a population at risk for IEM can assist in the prenatal diagnosis of an affected fetus.

Multidisciplinary Management of Fabry Disease: Current Perspectives

Fabry disease (FD) is a rare, recessive X-linked, multisystemic lysosomal storage disorder (LSD) that results from a deficiency in the hydrolase alpha-galactosidase A (α-GalA) caused by a GLA gene variant. The progressive accumulation of the glycosphingolipid globotriaosylceramide (Gb3) in organs such as skin, kidney, brain, joints, vascular walls and eyes are responsible for the wide spectrum of clinical manifestations, often unspecific. In result, clinically relevant and life-threatening complications, such as malignant ventricular arrhythmia, sudden cardiac death, end stage kidney failure and stroke may occur. In this review, we will describe the clinical features and the current perspectives in the multidisciplinary management Of FD patients.

Clinical Characteristics, Renal Involvement, and Therapeutic Options of Pediatric Patients With Fabry Disease

Inherited renal diseases represent 20% of the causes of end-stage renal diseases. Fabry disease, an X-linked lysosomal storage disorder, results from α-galactosidase A deficient or absent activity followed by globotriaosylceramide (Gb3) accumulation and multiorgan involvement. In Fabry disease, kidney involvement starts early, during intrauterine life by the Gb3 deposition. Even if chronic kidney disease (CKD) is discovered later in adult life in Fabry disease patients, a decline in glomerular filtration rate (GFR) can occur during adolescence. The first clinical sign of kidney involvement is represented by albuminuria. So, early and close monitoring of kidneys function is required: albuminuria and proteinuria, urinary albumin-to-creatinine ratio, serum creatinine, or cystatin C to estimate GFR, while urinary sediment with phase-contrast microscopy under polarized light may be useful in those cases where leucocyte α-Gal A activity and GLA genotyping are not available. Children with Fabry disease and kidney involvement should receive enzyme replacement therapy and nephroprotective drugs (angiotensin-converting enzyme inhibitors or angiotensin receptor blockers) to prevent or slow the progressive loss of kidney functions. Early diagnosis of Fabry disease is important as enzyme replacement therapy reduces symptoms, improves clinical features and biochemical markers, and the quality of life. More importantly, early treatment could slow or stop progressive organ damage in later life.

Fabry disease - current data and therapeutic approaches

Fabry disease represents an X-linked inherited disorder resulting in the accumulation of globotriaosylceramide (Gb3). This review explains the clinical manifestations and the possible therapies for this condition. Fabry disease is considered the second most frequent lysosomal storage disease. More than 1000 mutations of the galactosidase alpha (GLA) gene associated with this disorder have been identified. Pain, either episodic crises or chronic pain, is one of the earliest symptoms in Fabry disease. Gastrointestinal, ocular, ear or skeletal manifestations may complete the clinical picture. Cardiac and renal involvements are the most severe complications leading to organ failure and death. The cerebrovascular lesions may result in severe symptoms including stroke at younger ages. The diagnosis of Fabry disease may be put by enzymatic assays of the α-galactosidase A (AGAL-A) activity in plasma or leukocytes but genetic analysis remains the “gold standard” in identifying the precise mutation and even guiding the treatment. Enzyme replacement therapy (ERT) was the first step in treating subjects with Fabry disease. It proved important decrease of the number of sever clinical events and reduction of symptoms. Chemical chaperone therapy has many advantages including oral administration and was already approved in Europe and US, but it is suitable only for subjects with amenable mutations. Gene therapies (either ex vivo or in vivo) promise to represent a new era for many disorders including Fabry disease, the preliminary data being encouraging. Although many steps were taken in understanding the pathogeny of Fabry disease, future research is needed especially in the field of therapeutic approaches.

The myocardial phenotype of Fabry disease pre-hypertrophy and pre-detectable storage

Aims

Cardiac involvement in Fabry disease (FD) occurs prior to left ventricular hypertrophy (LVH) and is characterized by low myocardial native T1 with sphingolipid storage reflected by cardiovascular magnetic resonance (CMR) and electrocardiogram (ECG) changes. We hypothesize that a pre-storage myocardial phenotype might occur even earlier, prior to T1 lowering.

Methods and results

FD patients and age-, sex-, and heart rate-matched healthy controls underwent same-day ECG with advanced analysis and multiparametric CMR [cines, global longitudinal strain (GLS), T1 and T2 mapping, stress perfusion (myocardial blood flow, MBF), and late gadolinium enhancement (LGE)]. One hundred and fourteen Fabry patients (46 ± 13 years, 61% female) and 76 controls (49 ± 15 years, 50% female) were included. In pre-LVH FD (n = 72, 63%), a low T1 (n = 32/72, 44%) was associated with a constellation of ECG and functional abnormalities compared to normal T1 FD patients and controls. However, pre-LVH FD with normal T1 (n = 40/72, 56%) also had abnormalities compared to controls: reduced GLS (−18 ± 2 vs. −20 ± 2%, P < 0.001), microvascular changes (lower MBF 2.5 ± 0.7 vs. 3.0 ± 0.8 mL/g/min, P = 0.028), subtle T2 elevation (50 ± 4 vs. 48 ± 2 ms, P = 0.027), and limited LGE (%LGE 0.3 ± 1.1 vs. 0%, P = 0.004). ECG abnormalities included shorter P-wave duration (88 ± 12 vs. 94 ± 15 ms, P = 0.010) and T-wave peak time (T_onset – T_peak; 104 ± 28 vs. 115 ± 20 ms, P = 0.015), resulting in a more symmetric T wave with lower T-wave time ratio (T_onset – T_peak)/(T_peak – T_end) (1.5 ± 0.4 vs. 1.8 ± 0.4, P < 0.001) compared to controls.

Conclusion

FD has a measurable myocardial phenotype pre-LVH and pre-detectable myocyte storage with microvascular dysfunction, subtly impaired GLS and altered atrial depolarization and ventricular repolarization intervals.

Newborn Screening for Fabry Disease in Northeastern Italy: Results of Five Years of Experience

Fabry disease (FD) is a progressive multisystemic lysosomal storage disease. Early diagnosis by newborn screening (NBS) may allow for timely treatment, thus preventing future irreversible organ damage. We present the results of 5.5 years of NBS for FD by α-galactosidase A activity and globotriaosylsphingosine (lyso-Gb₃) assays in dried blood spot through a multiplexed MS/MS assay. Furthermore, we report our experience with long-term follow-up of positive subjects. We screened more than 170,000 newborns and 22 males were confirmed to have a GLA gene variant, with an incidence of 1:7879 newborns. All patients were diagnosed with a variant previously associated with the later-onset phenotype of FD or carried an unclassified variant (four patients) or the likely benign p.Ala143Thr variant. All were asymptomatic at the last visit. Although lyso-Gb₃ is not considered a reliable second tier test for newborn screening, it can simplify the screening algorithm when its levels are elevated at birth. After birth, plasma lyso-Gb₃ is a useful marker for non-invasive monitoring of all positive patients. Our study is the largest reported to date in Europe, and presents data from long-term NBS for FD that reveals the current incidence of FD in northeastern Italy. Our follow-up data describe the early disease course and the trend of plasma lyso-Gb₃ during early childhood.

Current and experimental therapeutics for Fabry disease

Fabry (or Anderson‐Fabry) is a rare pan‐ethnic disease affecting males and females. Fabry is an X‐linked lysosomal storage disease, affecting glycosphingolipid metabolism, that is caused by mutations of the GLA gene that codes for α‐galactosidase A. Fabry disease (FD) can be classified into a severe, classical phenotype, most often seen in men with no residual enzyme activity, that usually appear before 18 years and a usually milder, nonclassical (later‐onset) phenotype that usually appear above 18 years. Affected patients show multifactorial complications, including renal failure, cardiovascular problems, and neuropathy. In this review, we briefly report the clinical trials so far performed with the available therapies, and then we focus on the in vitro and the in vivo experimental models of the disease, to highlight the relevance in improving the existing therapeutics and understand the mechanism of this rare disorder. Current available in vivo and in vitro models can assist in better comprehension of the pathogenesis and underlying mechanisms of FD, thus the existing therapeutic approaches can be optimized, and new options can be developed.

Anderson-Fabry Disease: From Endothelial Dysfunction to Emerging Therapies

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

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.

Lyso-Gb3 associates with adverse long-term outcome in patients with Fabry disease

Background

Fabry disease (FD) is a rare X-linked lysosomal storage disease caused by mutations in the α-galactosidase A gene (GLA) leading to deficiency of α-galactosidase A and ultimately in progressive glycosphingolipid accumulation, especially globotriaosylceramide (Gb3) and its deacylated derivative globotriaosylsphingosine (Lyso-Gb3). The aim of the study was to assess plasma Lyso-Gb3 levels as a possible factor associated with adverse outcomes in FD.

Methods

In a cohort of 66 patients with genetically confirmed FD (26 males and 40 females), we analysed serum Lyso-Gb3 as a factor associated with adverse clinical outcomes in a long-term study. The main outcome was a composite endpoint of incident kidney replacement therapy, atrial fibrillation, pacemaker and/or implantable cardioverter defibrillator, cerebrovascular events or death, whichever occurred first.

Results

During the median follow-up time of 68 (40–80) months, events occurred in 19 (29%) of the patients. In a Cox multivariate regression analysis, Lyso-Gb3 levels (HR 4.62 (1.55 to 13.81); p=0.006) and the pretreatment exposure to Lyso-Gb3 (HR 3.41 (1.11 to 10.49); p=0.03) (both per SD increase) were significantly associated with adverse outcomes. If pretreatment Lyso-Gb3 exposure was added to multivariable logistic regression models containing age, sex, phenotype and enzyme replacement therapy as other covariates with the composite outcome as dependent variable, the area under the curve for the composite outcome significantly improved from 0.72 to 0.86 (p comparison=0.04).

Conclusion

Lyso-Gb3 is a significant risk factor associated with important clinical events. Whether treatment-related amelioration of Lyso-Gb3 levels will be associated with improved long-term outcome needs to be established in prospective intervention trials.

Trabecular complexity as an early marker of cardiac involvement in Fabry disease

AIMS

Fabry cardiomyopathy is characterized by glycosphingolipid storage and increased myocardial trabeculation has also been demonstrated. This study aimed to explore by cardiac magnetic resonance whether myocardial trabecular complexity, quantified by endocardial border fractal analysis, tracks phenotype evolution in Fabry cardiomyopathy.

METHODS AND RESULTS

Study population included 20 healthy controls (12 males, age 32±9) and 45 Fabry patients divided into three groups: 15 left ventricular hypertrophy (LVH)-negative patients with normal T1 (5 males, age 28±13; Group 1); 15 LVH-negative patients with low T1 (9 males, age 33±9.6; Group 2); 15 LVH-positive patients (11 males, age 53.5±9.6; Group 3). Trabecular fractal dimensions (Dfs) (total, basal, mid-ventricular, and apical) were evaluated on cine images. Total Df was higher in all Fabry groups compared to controls, gradually increasing from controls to Group 3 (1.27±0.02 controls vs. 1.29±0.02 Group 1 vs. 1.30±0.02 Group 2 vs. 1.34±0.02 Group 3; P<0.001). Group 3 showed significantly higher values of all Dfs compared to the other Groups. Both basal and total Dfs were significantly higher in Group 1 compared with controls (basal: 1.30±0.03 vs. 1.26±0.04, P =0.010; total: 1.29±0.02 vs. 1.27±0.02, P=0.044). Total Df showed significant correlations with: (i) T1 value (r=-0.569; P<0.001); (ii) LV mass (r=0.664, P<0.001); (iii) trabecular mass (r=0.676; P <0.001); (iv) Mainz Severity Score Index (r=0.638; P<0.001).

CONCLUSION

Fabry cardiomyopathy is characterized by a progressive increase in Df of endocardial trabeculae together with shortening of T1 values. Myocardial trabeculation is increased before the presence of detectable sphingolipid storage, thus representing an early sign of cardiac involvement.

Stroke and Fabry Disease: A Review of Literature

Fabry disease is an X-linked lysosomal storage disorder caused by a mutation in the alpha-galactosidase A (GLA) gene, leading to the deficiency of alpha-galactosidase A enzyme. The natural history of the affected patients (both males and females) includes neurovascular complications, such as cerebrovascular disease at a relatively young age. The pathophysiology behind the vascular involvement is primarily attributed to the accumulation of globotriaosylceramide and its derivatives in the vascular endothelium and vascular smooth muscle cells. MRI is the gold standard radiological investigation to detect the white matter lesions characteristic of Fabry disease's neurological involvement. More studies should focus on the utility of universally screening patients with young stroke for Fabry disease and the effectiveness of enzyme replacement therapy to prevent stroke. This review offers a synopsis of the current knowledge of the pathophysiology, neuroradiology, treatment, and prognosis of cerebrovascular disease in Fabry patients.

Biomarkers of Fabry Nephropathy: Review and Future Perspective

Progressive nephropathy is one of the main features of Fabry disease, which largely contributes to the overall morbidity and mortality burden of the disease. Due to the lack of specific biomarkers, the heterogeneity of the disease, and unspecific symptoms, diagnosis is often delayed. Clinical presentation in individual patients varies widely, even in patients from the same family carrying the same pathogenic GLA variant. Therefore, it is reasonable to anticipate that additional genomic, transcriptomic, proteomic, and metabolomics factors influence the manifestation and progression of the disease. The aim of this article is to provide an overview of nephropathy in Fabry patients and the biomarkers currently used in the diagnosis and follow-up. Current biomarkers are associated with late signs of kidney damage. Therefore, there is a need to identify biomarkers associated with early stages of kidney damage that would enable early diagnosis, which is crucial for effective treatment and prevention of severe irreversible complications. Recent advances in sequencing and -omics technologies have led to several studies investigating new biomarkers. We will provide an overview of the novel biomarkers, critically evaluate their clinical utility, and propose future perspectives, which we believe might be in their integration.

Effects of agalsidase-β administration on vascular function and blood pressure in familial Anderson-Fabry disease

Fabry is an X-linked disorder of glycosphingolipid metabolism that is caused by variants of the GLA gene that codes for α-galactosidase A, leading to lysosomal accumulation of globotriaosylceramide in many cell types. As a result, affected patients manifest with an increased risk of developing ischemic stroke, peripheral neuropathy, cardiac dysfunction, and chronic kidney disease. The protective effects of enzyme replacement therapy (ERT), the milestone in Fabry disease treatment, against globotriaosylceramide (GL-3) accumulation and Fabry disease progression are well known. However, the mechanism of action of ERT is not well understood. Since GL-3 also accumulates in the vascular endothelium, we investigated the effects of agalsidase-β, a recombinant human α-Gal enzyme approved for the treatment of Fabry disease. In this study, vascular function and blood pressure in four adult siblings affected by Fabry disease were evaluated upon agalsidase-β. In all patients, agalsidase-β infusion improves flow-mediated dilation and augmentation index. These changes occurred after the first infusion and were then maintained for the whole period of observation, i.e., 1 year, with more pronounced additional increments in flow-mediated dilation after the second agalsidase-β infusion. Blood pressure was also maintained at optimal levels in all of the patients for the whole period of observation. Our findings show that agalsidase-β administration can improve vascular function in patients suffering from Fabry disease. Changes in flow-mediated dilation and augmentation index persisted for the whole period of observation (1 year), thus suggesting that early substitutive therapy should be promoted in order to protect the cardiovascular system.

Cornea Verticillata in classical Fabry disease, first from Sri Lanka: a case report

BACKGROUND

Fabry disease is a rare inborn error of metabolism with profound clinical consequences if untreated. It is caused by the deficiency of α galactosidase A enzyme and is the only lysosomal storage disorder with an X linked inheritance. Confirmation requires genetic analysis of Galactosidase Alpha (GLA) Gene, which is often a challenge in resource-poor settings. Despite these technological limitations, specific clinical features in this condition can establish the diagnosis.

CASE PRESENTATION

We report on a 13-year old male who presented with an afebrile convulsion with a background history of chronic burning sensation of hands and feet and anhidrosis for 2 years duration with a similar history of episodic acroparesthesia in the other male sibling. The early clinical diagnosis was based on the history and detection of Cornea Verticillata on eye examination. Biochemical confirmation was established with detection of low α galactosidase A enzyme levels and a missense mutation of the Galactosidase Alpha (GLA) Gene (c.136C > T) established the genetic confirmation.

CONCLUSION

This is the first case of Fabry disease reported in Sri Lanka. Awareness of specific clinical features aided clinical diagnosis long before access to genetic confirmation was available.

Fabry keratopathy: manifestations and changes over time

AIMS

The goal was to find if changes in Fabry keratopathy were clinically observable over time. Also observed were variations of Fabry keratopathy, supplemental features, unique presentations and differences between keratopathies of right and left corneas and the same family and genotype.

METHODS

Biomicroscopic images of Fabry keratopathy in 10 persons with classic Fabry disease, 5 men and 5 women, were captured over an 18-month period. The keratopathies were categorised and scrutinised for changes over time, and differences between corneas of the same individual, family and genotype.

RESULTS

Fabry keratopathy ranged from mild change to marked change over 18 months. There was a great variety of whorl patterns. A few keratopathies were amorphous without vortices and many vortices were supplemented with amorphous features. All keratopathies were accompanied by diffuse epithelial haze. There was a range from negligible difference to marked difference between right and left eyes of the same individuals with similarities appearing as imprecise mirror images of each other. In some corneas, prominent vertical streams from the superior limbus integrated into the primary keratopathy. Comparisons between persons with the same family and genotype were obscured by gender and differences between right and left eyes.

CONCLUSIONS

Practitioners should be better able to detect Fabry disease having a fuller understanding of the variety of presentations of the dynamic, pathognomonic Fabry keratopathy. Routes of continuous centripetal renewal of corneal epithelium are spatially unique to each eye, in some cases subsidised by direct contribution of basal cells streamed from the superior limbus.

Longitudinal study on ocular manifestations in a cohort of patients with Fabry disease

Purpose

This study aims to assess the evolution of ocular manifestations in a cohort of Fabry patients.

Methods

This is a prospective observational study conducted from 2013 to 2017 (5 consecutive exams). All subjects underwent a comprehensive ocular examination including oriented case history, refraction, corneal topography, biomechanical corneal properties and pachometry assessments, aberrometry, anterior segment evaluation, double-frequency visual field (FDT), intra-ocular pressure, and ocular fundus. At baseline, 41 subjects enrolled but 9 dropped-out and 4 files were not kept for analysis (missing data). Remaining 28 subjects were classified into: Group 1 -hemizygotes (HMZ), all on enzyme replacement therapy (ERT) (N = 10); Group 2 -heterozygotes (HTZ) actively ERT-treated (N = 8), and Group 3 -HTZ not treated (N = 10).

Results

There is a high intra and inter-subjects variability. At baseline, prevalence of the ocular manifestations found is similar to published data: cornea verticillata (89.2%), conjunctival vessels tortuosity (85.7%), corneal haze (67.8%), retinal vessels tortuosity (64.2%), anterior cataract (39.2%) and posterior cataract (28.5%). Prevalence for new elements are found: upper lid vessels toricity (96.4%) and micro-aneurysms (42.8%). At the end, micro-aneurysms (+82%), posterior cataract (+75%) corneal haze (+21%) anterior cataract (+17%) and retinal vessels tortuosities (+4%) evolved in prevalence and severity despite the fact that 68% of the patients were on ERT. Treated heterozygotes evolved more than other groups (p>0.05).

Conclusion

ERT does not seem to halt the clinical evolution of several ocular manifestations. Longer observational time and objective grading systems may be required to fully confirm these findings.

Enzyme Replacement Therapy During Pregnancy in Fabry Patients : Review of Published Cases of Live Births and a New Case of a Severely Affected Female with Fabry Disease and Pre-eclampsia Complicating Pregnancy

Fabry disease (FD) is an X-linked, lysosomal storage disease. Mutations in the gene coding for alpha-galactosidase A lead to globotriaosylceramide (Gb-3) accumulation in lysosomes and in placenta and umbilical cord. Impact of FD and treatment with enzyme replacement (ERT) on foetal development is undisclosed.A 38-year-old primigravida with FD (G85N) is reported. She has 50% reduced alpha-galactosidase A activity and elevated plasma and urine-Gb-3. She was severely affected with ischaemic stroke at age 23, hypertension, albuminuria and moderately reduced renal function. ERT was initiated at age 23 years in 2001 and continued during spontaneous pregnancy at age 38. In third trimester she developed moderate-to-severe pre-eclampsia, successfully managed by methyldopa. Chorion villus sampling revealed a male foetus without the maternal gene mutation. Planned Caesarean section was performed without complications at gestational age week 38 + 6, delivering a healthy boy. Histopathological placental examination showed no sign of Gb-3 accumulation. Literature survey disclosed a total of 12 cases, 8 were treated with ERT during pregnancy and 5 infants inherited the family mutation. All outcomes were successful. In the six cases with available placental histopathological examination, Gb-3 accumulation was only seen on the foetal side if the foetus had the inherited mutation.In conclusion, the present case, describing the first data from a severely affected FD patient receiving ERT during pregnancy complicated by pre-eclampsia, together with all other published cases, has emphasized that ERT is safe during pregnancy and resulting in successful foetal outcome; despite this, ERT is by the health authorities advised against during pregnancy.

Genotype, phenotype and disease severity reflected by serum LysoGb3 levels in patients with Fabry disease

BACKGROUND

Fabry disease (FD) is a rare X-linked lysosomal storage disease caused by mutations in the α-galactosidase A (GLA) gene causing deficiency of α-galactosidase A which results in progressive glycosphingolipid accumulation, especially globotriaosylceramide (Gb3), in body liquids and lysosomes. In a large cohort of FD patients, we aimed to establish genotype/phenotype relations as indicated by serum LysoGb3 (deacylated Gb3).

METHODS

In 69 consecutive adult FD patients (males: n=28 (41%)) with a GLA-mutation confirmed diagnosis, we conducted a multidisciplinary clinical characterization during their routine annual examinations, and measured serum LysoGb3 levels by high-sensitive electrospray ionization liquid chromatography tandem mass spectrometry.

RESULTS

Serum levels of LysoGb3 were significantly higher in Classic compared with Later-Onset phenotype and higher in the latter compared with controls, both in males (52 [40-83] vs 9.5 [4.5-20] vs 0.47 [0.41-0.61] ng/ml, P<0.001) and in females (9.9 [7.9-14] vs 4.9 [1.6-4.9] vs 0.41 [0.33-0.48] ng/ml, P<0.001), respectively. Multivariate linear regression analysis showed that LysoGb3 levels were independently associated with, serum creatinine (β=0.09, 95%CI 0.04-0.13, P<0.001) and the presence of cardiomyopathy (β=25, 95%CI 9.8-41, P=0.002). LysoGb3 levels were higher in males with frame-shift and nonsense mutations than in males with missense mutations (84 [72-109] vs 41 [37-52] ng/ml, P=0.002).

CONCLUSION

LysoGb3 relates to disease severity, enzyme replacement response, and to the genotype severity in males. LysoGb3 supports identifying patients at risk who require intensive monitoring and treatment. LysoGb3 appears to be one marker of metabolic phenotyping of FD.

Enzyme replacement therapy in a patient of heterozygous Fabry disease: clinical and pathological evaluations by repeat kidney biopsy and a successful pregnancy

Fabry disease is a rare X-linked lysosomal storage disorder of glycosphingolipid catabolism caused by deficient activity of the lysosomal hydrolase alpha-galactosidase A (ɑ-Gal A). A 20-year-old woman was referred to our hospital because of proteinuria and persistent macroscopic hematuria. Based on the typical renal pathological findings, deficient activity of the ɑ-Gal A, and heterozygous mutation in the ɑ-Gal A gene, she was diagnosed with Fabry disease. After 1 year of enzyme replacement therapy with agalsidase alfa at 0.2 mg/kg every other week, the patient's proteinuria and hematuria were disappeared. In our patient, enzyme replacement therapy with agalsidase alfa was observed to be safe and well-tolerated during her pregnancy, with no significant negative effects on her or her child. Here, we report clinical and pathological evaluations of a patient through repeat kidney biopsy after 6 years of enzyme replacement therapy. Furthermore, we discussed the appropriate enzyme replacement therapy and its safety in pregnant women with Fabry disease.

Early Renal Involvement in a Girl with Classic Fabry Disease

Fabry disease is an X-linked lysosomal storage disorder resulting from the deficiency or absence of the enzyme alpha galactosidase A; this defect leads to the systemic accumulation of globotriaosylceramide and its metabolites. Organic involvement in men is well known, but in women it is controversial, mainly due to the random X-chromosome inactivation in each of their cells (Lyon hypothesis). This would explain why women (heterozygotes) present a wide variability in the severity of their phenotype. The manifestations are multisystemic and begin in early childhood, reaching a severe compromise in adulthood. Typical acroparesthesia in hands and feet, gastrointestinal symptoms, angiokeratomas, dyshidrosis, hearing loss, arrhythmias, hypertrophic cardiomyopathy, cerebrovascular accidents, and renal failure can be observed. Nephropathy is one of the major complications of Fabry disease. Glomerular and vascular changes are present before progression to overt proteinuria and decreased glomerular filtration rate, even in pediatric patients. A case of incipient renal involvement in a girl with classic Fabry disease is reported.

Case study on the pathophysiology of Fabry disease: abnormalities of cellular membranes can be reversed by substrate reduction in vitro

It is still not entirely clear how α-galactosidase A (GAA) deficiency translates into clinical symptoms of Fabry disease (FD). The present communication investigates the effects of the mutation N215S in FD on the trafficking and processing of lysosomal GAA and their potential association with alterations in the membrane lipid composition. Abnormalities in lipid rafts (LRs) were observed in fibroblasts isolated from a male patient with FD bearing the mutation N215S. Interestingly, LR analysis revealed that the distribution of cholesterol and flotillin-2 are distinctly altered in the Fabry fibroblasts when compared with that of the wild-type cells. Furthermore, increased levels of glycolipid globotriaosylceramide 3 (Gb3) and sphingomyelin (SM) were observed in non-raft membrane fractions of Fabry cells. Substrate reduction with N-butyldeoxynojirimycin (NB-DNJ) in vitro was capable of reversing these abnormalities in this patient. These data led to the hypothesis that alterations of LRs may contribute to the pathophysiology of Morbus Fabry. Furthermore, it may be suggested that substrate reduction therapy with NB-DNJ might be a promising approach for the treatment of GAA deficiency at least for the selected patients.

Metabolic progression to clinical phenotype in classic Fabry disease

Background

Fabry disease is an X-linked lysosomal storage disorder due to α-galactosidase A (α-Gal A) deficiency. Clinical onset of Fabry disease is preceded by significant storage of globotriaosylceramide (Gb3) and related glycosphingolipids, but the extent of the metabolic progression before symptoms is unknown. Using a newly recognized effector and marker of Fabry disease, globotriaosylsphingosine (LysoGb3), we aimed to provide a metabolic picture of classic Fabry disease from the neonatal period to childhood.

Methods

LysoGb3 was assessed at different times in two brothers with classic Fabry disease (genotype c. 370–2 A > G). The firstborn was diagnosed after clinical onset at 11 years of age, whereas the second-born was diagnosed in the neonatal period. LysoGb3 was measured in dried blood spots by high-sensitive electrospray ionization liquid chromatography tandem mass spectrometry.

Results

Blood LysoGb3 concentrations were consistent with patients’ age and clinical picture, with lower levels in the asymptomatic neonate (19.1 ng/ml) and higher levels in the symptomatic child (94.3 ng/ml). In the second-born, LysoGb3 doubled during the first 5 months of life (37.4 ng/ml), reaching ~40% concentration observed in the symptomatic period. The neonatal LysoGb3 concentration in classic Fabry disease exceeded that observed in normal subjects by over 15 times.

Conclusions

A substantial increase of LysoGb3 was documented during the first months of life in classic Fabry disease, suggesting an early plateau during the pre-symptomatic period. Such a progressive metabolic trend during the pre-symptomatic period implies the potential definition of a metabolic threshold useful for a preventive therapeutic approach of classic Fabry disease. Additionally, the consistent increase of LysoGb3 in the neonatal period in classic Fabry disease suggests LysoGb3 as a useful marker for improving the specificity of newborn screening for Fabry disease.

Screening, diagnosis, and management of patients with Fabry disease: conclusions from a "Kidney Disease: Improving Global Outcomes" (KDIGO) Controversies Conference

Patients with Fabry disease (FD) are at a high risk for developing chronic kidney disease and cardiovascular disease. The availability of specific but costly therapy has elevated the profile of this rare condition. This KDIGO conference addressed controversial areas in the diagnosis, screening, and management of FD, and included enzyme replacement therapy and nonspecific standard-of-care therapy for the various manifestations of FD. Despite marked advances in patient care and improved overall outlook, there is a need to better understand the pathogenesis of this glycosphingolipidosis and to determine the appropriate age to initiate therapy in all types of patients. The need to develop more effective specific therapies was also emphasized.

Fabry's disease: an example of cardiorenal syndrome type 5

Cardiorenal syndrome type 5 (CRS-5) includes conditions where there is a simultaneous involvement of the heart and kidney from a systemic disorder. This is a bilateral organ cross talk. Fabry's disease (FD) is a devastating progressive inborn error of metabolism with lysosomal glycosphingolipid deposition in variety of cell types, capillary endothelial cells, renal, cardiac and nerve cells. Basic effect is absent or deficient activity of lysosomal exoglycohydrolase a-galactosidase A. Renal involvement consists of proteinuria, isosthenuria, altered tubular function, presenting in second or third decade leading to azotemia and end-stage renal disease in third to fifth decade mainly due to irreversible changes to glomerular, tubular and vascular structures, especially highlighted by podocytes foot process effacement. Cardiac involvement consists of left ventricular hypertrophy, right ventricular hypertrophy, arrhythmias (sinus node and conduction system impairment), diastolic dysfunction, myocardial ischemia, infarction, transmural replacement fibrosis, congestive heart failure and cardiac death. Management of FD is based on enzymatic replacement therapy and control of renal (with anti-proteinuric agents such as angiotensin-converting enzyme inhibitors-and/or angiotensin II receptor blockers), brain (coated aspirin, clopidogrel and statin to prevent strokes) and heart complications (calcium channel blockers for ischemic cardiomyopathy, warfarin and amiodarone or cardioverter device for arrhythmias).

Paediatric Fabry disease

Fabry disease is a rare, progressive X-linked inborn error of the glycosphingolipid metabolic pathway. Mutations of the GLA gene result in deficiency of the lysosomal enzyme, α-galactosidase A (α-Gal A) with accumulation of glycosphingolipids, particularly globotriaosylceramide (GL3) in the vascular endothelium of various tissues. Accumulation of GL3 eventually leads to life threatening renal, cardiac and cerebrovascular complications typically in the third to fifth decades of life. The first signs and symptoms of classic Fabry disease however appear in childhood but diagnosis is often delayed. The symptoms most commonly experienced in childhood include neuropathic pain, gastrointestinal dysfunction, hyperhidrosis and heat intolerance. Timely diagnosis is important as early treatment with enzyme replacement therapy reduces GL3 accumulation, can stabilize disease progression and potentially prevent irreversible organ damage. Physicians should be familiar with the signs and symptoms of Fabry disease in childhood and be particularly vigilant for unusual or non-specific but recurrent or episodic symptoms.

Gastrointestinal Symptoms of Patients with Fabry Disease

In order to characterize gastrointestinal (GI) symptoms of 50 patients with Fabry disease (FD) (22 M; age range: 4–70 y; 35 adults and 15 children), validated questionnaires of GI symptoms were used to diagnose the functional gastrointestinal disorders (FGIDs) of the patients with GI symptoms (33/50 (66%); 25/35 adults and 8/15 children) according to Rome III criteria. In 16/25 of these adults and 2/8 of these children, the symptoms mimicked FGID. The adult subgroup included patients with unspecified functional bowel disorder (n = 9), functional bloating (n = 7), and IBS (n = 5), and the child subgroup included patients with abdominal migraine (n = 1) and IBS (n = 1). Among the 25 adults, 14 reported feeling full after a regular-size meal, and 12 complained of abdominal bloating/distension. All of the children with GI symptoms complained of low abdominal pain associated with changes in the form of the stool/improvements with defecation. In conclusion, according to Rome III criteria, the most frequent diagnoses of FGID among the adults with FD were unspecified functional bowel disorder, followed by functional bloating and IBS. The most frequent GI symptom in the children in our population was IBS-like abdominal pain, while the adults exhibited a full feeling following a regular-size meal and abdominal bloating/distension.

Fabry disease and the heart

Fabry disease is induced by a mutation in the alpha-galactosidase A gene, causing a deficiency of the enzyme alpha-galactosidase A. (1) The enzyme defect leads to progressive intracellular accumulation of globotriaosylceramide in lysosomes of various tissues and organs, including heart, kidney and nerve system. Cardiac involvement is common and is presenting as concentric left ventricular hypertrophy. Myocardial replacement fibrosis is a typical feature of more advanced stages of Fabry cardiomyopathy, first limited to the mid-myocardial layers of the basal postero-lateral wall, then spreading to transmural fibrosis. Since 2001, enzyme replacement therapy is available. If therapy is started early, before myocardial fibrosis has developed, a long-term improvement of myocardial morphology, function and exercise capacity can be achieved. In end-stage cardiomyopathy enzyme replacement therapy might prevent further progression of the disease. This review provides an overview of Fabry disease, with a focus on cardiac involvement with its characteristic features, clinical presentation and possible treatment.

A Retrospective Survey Studying the Impact of Fabry Disease on Pregnancy

Fabry disease (FD) is a lysosomal storage disorder resulting from a deficiency of lysosomal enzyme α-galactosidase A (α-gal A). Reduced or missing α-gal A enzyme results in the storage of globotriaosylceramide (GL3) and related glycosphingolipids in the cellular lysosomes throughout the body. The majority of GL3 buildup occurs in the body's vasculature resulting in narrowed blood vessels and an increased risk for strokes, transient ischemic attacks, and deep vein thrombosis. Theoretical concerns have been raised about increased pregnancy complications in women affected by FD as glycosphingolipid storage has been found in both maternal- and fetal-derived placental tissues. This retrospective study was conducted to better understand risks for women with FD during pregnancy. Survey questions included queries about prenatal medications, teratogenic exposures, prenatal testing, common pregnancy complications, Fabry symptoms during pregnancy, obstetrical history, and immediate neonatal history. In total, 41 affected women completed the survey. Results indicate several Fabry-related symptoms and features may worsen during pregnancy, including gastrointestinal symptoms, acroparesthesias, proteinuria, headaches, and postpartum depression. Although no life-threatening complications were reported, a statistically significant increased frequency of hypertension was observed when comparing data from this study to the general population (p < 0.05) and previous publications (p < 0.001). Limitations include sample size and recall bias. Though this survey sampling of women was small and required women to recall their past pregnancy experiences, the findings suggest that when pregnant, women with FD should be aware of potential worsening of FD symptoms and may benefit from consulting with a maternal-fetal medicine specialist.

Fabry disease in infancy and early childhood: a systematic literature review

PURPOSE

Fabry disease is a pan-ethnic, progressive, X-linked genetic disorder that commonly presents in childhood and is caused by deficient activity of the lysosomal enzyme alpha-galactosidaseA (α-gal A). Symptoms of Fabry disease in the pediatric population are well described for patients over five years of age; however, data are limited for infancy and early childhood. The purpose of this article is to delineate the age of detection for specific Fabry symptoms in early childhood.

METHODS

A systematic retrospective analysis of PubMed indexed, peer-reviewed publications and case reports in the pediatric Fabry population was performed to review symptoms in patients reported before 5 years of age.

RESULTS

The most frequently reported symptom in all age groups under 5 years was acroparesthesias/neuropathic pain, reported in 9 children, ranging in age from 2.0-4.0 years. Also notable is the frequency of gastrointestinal issues reported in 6 children aged 1.0-4.1 years of age.

CONCLUSION

This article finds clear evidence that symptoms can occur in early childhood, before age 5 years. Given early presenting symptoms and the ability to monitor these disease hallmarks, a timely referral to a medical geneticist or other specialty clinician experienced in managing children with Fabry disease is strongly indicated.

Glycosphingolipid profile of the apical pole of human placental capillaries: the relevancy of the observed data to Fabry disease

A series of six full-term placentas and umbilical cords were examined using the in situ detection of globotriaosylceramide (Gb3Cer), GM1 ganglioside (GM1), GM3 ganglioside (GM3), cholesterol and caveolin 1. Immunohistochemical study showed uniform distinct staining of the apical membrane of villous capillary endothelial cells for Gb3Cer, GM1, GM3 and cholesterol. There was also a strong signal for caveolin 1. The immunophenotype suggests the presence of caveola-associated raft microdomains. The immunophenotype was almost completely shared with the extravillous intravascular trophoblast in the basal plate. It was absent in the endothelial cells of umbilical vessels and in the capillaries of somatic structures (heart, lung, skeletal muscle and skin) in neonates as well as in adults, including capillaries of the proliferative endometrium. Results of in situ analyses were confirmed by lipid chromatographic analysis of tissue homogenates and by tandem mass spectrometry. Lysosomal Gb3Cer turnover was followed in three placentas including umbilical cords from Fabry disease (α-galactosidase A deficiency). Lysosomal storage was restricted to vascular smooth muscle cells and to endothelial cells of umbilical vessels. Placental villous capillary endothelial cells displaying a strong non-lysosomal staining for Gb3Cer were free of lysosomal storage.

Biomarkers in the diagnosis of lysosomal storage disorders: proteins, lipids, and inhibodies

A biomarker is an analyte indicating the presence of a biological process linked to the clinical manifestations and outcome of a particular disease. In the case of lysosomal storage disorders (LSDs), primary and secondary accumulating metabolites or proteins specifically secreted by storage cells are good candidates for biomarkers. Clinical applications of biomarkers are found in improved diagnosis, monitoring disease progression, and assessing therapeutic correction. These are illustrated by reviewing the discovery and use of biomarkers for Gaucher disease and Fabry disease. In addition, recently developed chemical tools allowing specific visualization of enzymatically active lysosomal glucocerebrosidase are described. Such probes, coined inhibodies, offer entirely new possibilities for more sophisticated molecular diagnosis, enzyme replacement therapy monitoring, and fundamental research.

Fabry disease complicating pregnancy

BACKGROUND

Few cases of Fabry disease, an X-linked lysosomal storage disorder, complicating pregnancy are reported.

CASE

A 36-year-old primigravida with known Fabry disease manifest with acroparesthesias, tinnitus, and hearing loss delivered a healthy unaffected infant at term.

CONCLUSION

A symptomatic Fabry carrier may experience an otherwise uncomplicated pregnancy in the absence of vital organ involvement.