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Background
Anderson–Fabry disease (FD) is an X-linked lysosomal storage disorder with varying organ involvement and symptoms, depending on the underlying mutation in the alpha-galactosidase A gene (HGNC: GLA). With genetic testing becoming more readily available, it is crucial to precisely evaluate pathogenicity of each genetic variant, in order to determine whether there is or might be not a need for FD-specific therapy in affected patients and relatives at the time point of presentation or in the future.
Methods
This case series investigates the clinical impact of the specific GLA gene variant c.376A>G (p.Ser126Gly) in five (one heterozygous and one homozygous female, three males) individuals from different families, who visited our center between 2009 and 2021. Comprehensive neurological, nephrological and cardiac examinations were performed in all cases. One patient received a follow-up examination after 12 years.
Results
Index events leading to suspicion of FD were mainly unspecific neurological symptoms. However, FD-specific biomarkers, imaging examinations (i.e., brain MRI, heart MRI), and tissue-specific diagnostics, including kidney and skin biopsies, did not reveal evidence for FD-specific symptoms or organ involvement but showed normal results in all cases. This includes findings from 12-year follow-up in one patient with renal biopsy.
Conclusion
These findings suggest that p.Ser126Gly represents a benign GLA gene variant which per se does not cause FD. Precise clinical evaluation in individuals diagnosed with genetic variations of unknown significance should be performed to distinguish common symptoms broadly prevalent in the general population from those secondary to FD.
Background
Although Fabry disease (FD) is an X-linked lysosomal storage disorder caused by mutations in the α-galactosidase A gene (GLA), women may develop severe symptoms. We investigated X-chromosomal inactivation patterns (XCI) as a potential determinant of symptom severity in FD women.
Patients and Methods
We included 95 women with mutations in GLA (n = 18 with variants of unknown pathogenicity) and 50 related men, and collected mouth epithelial cells, venous blood, and skin fibroblasts for XCI analysis using the methylation status of the androgen receptor gene. The mutated X-chromosome was identified by comparison of samples from relatives. Patients underwent genotype categorization and deep clinical phenotyping of symptom severity.
Results
43/95 (45%) women carried mutations categorized as classic. The XCI pattern was skewed (i.e., ≥75:25% distribution) in 6/87 (7%) mouth epithelial cell samples, 31/88 (35%) blood samples, and 9/27 (33%) skin fibroblast samples. Clinical phenotype, α-galactosidase A (GAL) activity, and lyso-Gb3 levels did not show intergroup differences when stratified for X-chromosomal skewing and activity status of the mutated X-chromosome.
Conclusions
X-inactivation patterns alone do not reliably reflect the clinical phenotype of women with FD when investigated in biomaterial not directly affected by FD. However, while XCI patterns may vary between tissues, blood frequently shows skewing of XCI patterns.
Background
Fabry disease (FD) is an X‐linked lysosomal storage and multi‐system disorder due to mutations in the α‐galactosidase A (α‐GalA) gene. We investigated the impact of individual amino acid exchanges in the α‐GalA 3D‐structure on the clinical phenotype of FD patients.
Patients and methods
We enrolled 80 adult FD patients with α‐GalA missense mutations and stratified them into three groups based on the amino acid exchange location in the α‐GalA 3D‐structure: patients with active site mutations, buried mutations and other mutations. Patient subgroups were deep phenotyped for clinical and laboratory parameters and FD‐specific treatment.
Results
Patients with active site or buried mutations showed a severe phenotype with multi‐organ involvement and early disease manifestation. Patients with other mutations had a milder phenotype with less organ impairment and later disease onset. α‐GalA activity was lower in patients with active site or buried mutations than in those with other mutations (P < 0.01 in men; P < 0.05 in women) whilst lyso‐Gb3 levels were higher (P < 0.01 in men; <0.05 in women).
Conclusions
The type of amino acid exchange location in the α‐GalA 3D‐structure determines disease severity and temporal course of symptom onset. Patient stratification using this parameter may become a useful tool in the management of FD patients.
Long-term treatment effect studies in large female Fabry patient groups are challenging to design because of phenotype heterogeneity and lack of appropriate comparison groups, and have not been reported. We compared long-term cardiomyopathy and kidney function outcomes after agalsidase beta treatment with preceding treatment-naive outcomes.
Methods and results Self-controlled pretreatment and post-treatment comparison (piecewise mixed linear modelling) included Fabry female patients ≥18 years at treatment initiation who received agalsidase beta (0.9–1.1 mg/kg every other week) for ≥2 years, with ≥2 pretreatment and ≥2 post-treatment outcome measurements during 10-year follow-up. Left ventricular posterior wall thickness (LVPWT)/interventricular septal thickness (IVST) and estimated glomerular filtration rate (eGFR, Chronic Kidney Disease Epidemiology Collaboration creatinine equation) analyses included 42 and 86 patients, respectively, aged 50.0 and 46.3 years at treatment initiation, respectively. LVPWT and IVST increased pretreatment (follow-up 3.5 years) but stabilized during 3.6 years of treatment (LVPWT: n = 38, slope difference [95% confidence interval (CI)] = - 0.41 [ - 0.68, - 0.15] mm/year, P\(_{pre–post difference}\)<0.01; IVST: n = 38, slope difference =-0.32 [-0.67, 0.02] mm/year, P\(_{pre–post difference}\) = 0.07). These findings were not modified by renal involvement or antiproteinuric agent use. Compared with the treatment-naive period (follow-up 3.6 years), eGFR decline remained modest and stabilized within normal ranges during 4.1 years of treatment (slope difference, 95% CI: -0.13 [-1.15, 0.89] mL/min/1.73m\(^2\)/year, P\(_{pre–post difference}\) = 0.80).
Conclusions Cardiac hypertrophy, progressing during pretreatment follow-up, appeared to stabilize during sustained agalsidase beta treatment. eGFR decline remained within normal ranges. This suggests that treatment may prevent further Fabry-related progression of cardiomyopathy in female patients and maintain normal kidney function.
Fabry Disease (FD) is a rare, X-linked, lysosomal storage disease that mainly causes renal, cardiac and cerebral complications. Enzyme replacement therapy (ERT) with recombinant alpha-galactosidase A is available, but approximately 50% of male patients with classical FD develop inhibiting anti-drug antibodies (iADAs) that lead to reduced biochemical responses and an accelerated loss of renal function. Once immunization has occurred, iADAs tend to persist and tolerization is hard to achieve. Here we developed a pre-treatment prediction model for iADA development in FD using existing data from 120 classical male FD patients from three European centers, treated with ERT. We found that nonsense and frameshift mutations in the α-galactosidase A gene (p = 0.05), higher plasma lysoGb3 at baseline (p < 0.001) and agalsidase beta as first treatment (p = 0.006) were significantly associated with iADA development. Prediction performance of a Random Forest model, using multiple variables (AUC-ROC: 0.77) was compared to a logistic regression (LR) model using the three significantly associated variables (AUC-ROC: 0.77). The LR model can be used to determine iADA risk in individual FD patients prior to treatment initiation. This helps to determine in which patients adjusted treatment and/or immunomodulatory regimes may be considered to minimize iADA development risk.
Bei Morbus Fabry handelt es sich um eine X-chromosomal rezessiv vererbbare lysosomale Speichererkrankung. Im Vordergrund der kardialen Beteiligung stehen eine progrediente Herzinsuffizienz, bedingt durch eine linksventrikuläre Hypertrophie mit kardialer Fibrosierung, sowie eine Mitbeteiligung des Reizleitungssystems.
Bei 150 Patienten wurden im Zeitraum von 2001-2009 neben einer klinischen Untersuchung ein EKG, eine Echokardiographie, ein Belastungs-EKG und teilweise auch eine Magnetresonanztomographie durchgeführt. Zum Vergleich der Patientenentwicklung wurde jeweils das jüngste Follow-up Ergebnis mit den Baseline-Daten verglichen.
Es konnte eine signifikante Korrelation zwischen der QRS-Dauer und der Wandstärke in der Echokardiographie und der Magnetresonanztomographie eindeutig nachgewiesen werden. Eine myokardiale Fibrose ist bei normalen Ruhe-EKG-Parametern nahezu auszuschließen. In der Untersuchung des Langzeit-EKGs fanden sich bei einigen Patienten höhergradige ventrikuläre Rhythmusstörungen, welche als erhöhtes individuelles Risiko und als bedeutender Faktor der Sterblichkeit bei Morbus Fabry zu werten sind.
Background
Fabry Disease (FD) is an X-linked hereditary lysosomal storage disorder which leads to a multisystemic intralysosomal accumulation of globotriaosylceramid (Gb3). Besides prominent renal and cardiac organ involvement, patients commonly complain about vestibulocochlear symptoms like high-frequency hearing loss, tinnitus and vertigo. However, comprehensive data especially on vertigo remain scarce. The aim of this study was to examine the prevalence and characteristics of vertigo and hearing loss in patients with FD, depending on renal and cardiac parameters and get hints about the site and the pattern of the lesions.
Methods
Single-center study with 57 FD patients. Every patient underwent an oto-rhino-laryngological examination as well as videonystagmography and vestibular evoked myogenic potentials (VEMPs) and audiological measurements using pure tone audiometry and auditory brainstem response audiometry (ABR). Renal function was measured by eGFR, cardiac impairment was graduated by NYHA class.
Results
More than one out of three patients (35.1%) complained about hearing loss, 54.4% about vertigo and 28.1% about both symptom. In 74% a sensorineural hearing loss of at least 25 dB was found, ABR could exclude any retrocochlear lesion. Caloric testing showed abnormal values in 71.9%, VEMPs were pathological in 68%. A correlation between the side or the shape of hearing loss and pathological vestibular testing could not be revealed.
Conclusions
Hearing loss and vertigo show a high prevalence in FD. While hearing loss seems due to a cochlear lesion, peripheral vestibular as well as central nervous pathologies cause vertigo. Thus, both the site of lesion and the pathophysiological patterns seem to differ.
Background
Fabry disease (FD) is an X-linked recessive hereditary lysosomal storage disorder which results in the accumulation of globotriaosylceramid (Gb3) in tissues of kidney and heart as well as central and peripheral nervous system.
Besides prominent renal and cardiac organ involvement, cochlear symptoms like high-frequency hearing loss and tinnitus are frequently found with yet no comprehensive data available in the literature.
Objective
To examine hearing loss in patients with FD depending on cardiac and renal function.
Material and methods
Single-center study with 68 FD patients enrolled between 2012 and 2016 at the Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery of the University of Würzburg. Every subject underwent an oto-rhino-laryngological examination as well as behavioral, electrophysiological and electroacoustical audiological testing. High-frequency thresholds were evaluated by using a modified PTA\(_{6}\) (0.5, 1, 2, 4, 6, 8) and HF-PTA (6, 8 kHz). Renal function was measured by eGFR, cardiac impairment was graduated by NYHA class.
Results
Sensorineural hearing loss was detected in 58.8% of the cohort, which occurred typically in sudden episodes and affected especially high frequencies. Hearing loss is asymmetric, beginning unilaterally and affecting the contralateral ear later. Tinnitus was reported by 41.2%. Renal and cardiac impairment influenced the severity of hearing loss (p < 0.05).
Conclusions
High frequency hearing loss is a common problem in patients with FD. Although not life-threatening, it can seriously reduce quality of life and should be taken into account in diagnosis and therapy. Optimized extensive hearing assessment including higher frequency thresholds should be used.
Background
X-chromosomal inheritance patterns and generally rare occurrence of Fabry disease (FD) account for mono-mutational hemizygous male and heterozygous female patients. Female mutation carriers are usually clinically much less severely affected, which has been explained by a suggested mosaicism in cell phenotype due to random allele shutdown. However, clinical evidence is scarce and potential additional effects in female gene carriers, which might account for specific clinical characteristics such as less severe chronic kidney disease, are yet unknown.
Case presentation
This article reports on a 45 year old female patient carrying the two alpha-galactosidase A gene mutations c.416A > G, p.N139S in exon 3 and c.708G > C, p.W236C in exon 5, but still showing only mild organ manifestations.
Conclusion
This current case highlights the importance of careful clinical characterization in patients with Fabry disease, who may show additional rare constellations and, therefore, are in need of personalized medicine. The impact of potential additional protective effects exceeding the presence of a non-pathogenic GLA allele in female gene carriers requires further investigation.