Prevalence and Clinical Characteristics of Fabry Disease in Chinese Patients With Hypertrophic Cardiomyopathy

The vestibular and oculomotor dysfunction in Fabry disease: a cohort study in China

OBJECTIVE

Whereas a few studies have evaluated vestibular involvement in Fabry disease (FD), the relationship between vestibular/oculomotor abnormalities and disease-specific biomarkers remain unclear. Therefore, we seek to evaluate these quantitatively and analyze their relationship with disease phenotype and biomarkers in FD.

METHODS

This cohort study enrolled 37 Chinese FD patients registered in our center. The vestibular/oculomotor examinations were performed, including the videonystagmography, the caloric test and the video head-impulse test. Statistical analyses were made between different subgroups of patients.

RESULTS

Visuo-oculomotor dysfunctions were found in 30/37 (81.1%) patients. Vestibulo-oculomotor dysfunctions were revealed in 9/22 (40.9%) patients. Statistical tests showed: (1) significantly higher Mainz Severity Score Index in patients with prolonged saccade latency [20(18,33) VS 13(9,22), p = 0.008] and vestibulo-oculomotor dysfunction [23(20,31) VS 9(5.5,12.5), p = 0.024], (2) significantly higher total small-vessel disease score in subgroups with prolonged saccade latency [2.5(1,3.5) VS 1(0,2), p = 0.038], defective smooth pursuit [3(2,4) VS 1(0,2), p = 0.003], defective optokinetic nystagmus [4(2,4) VS 1(0.2), p = 0.009] and vestibulo-oculomotor dysfunction [1(1,3) VS 0(0,1), p = 0.028], (3) significantly lower α-Gal A activity (μmol/L/h) in subgroups with defective saccades [0.44(0.25,1.93) VS 1.85(0.75,5.52), p = 0.015] and defective smooth pursuit [0.30(0.17,0.44) VS 0.96(0.39,2.40), p = 0.008], and (4) significantly elevated plasma globotriaosylsphingosine (ng/ml) in patients with defective saccades [74.16(11.05,89.18) VS 10.64(7.08,36.32), p = 0.034], than in patients without those abnormalities.

CONCLUSION

A high incidence of extensive vestibular and oculomotor dysfunction was observed in patients with FD, with the neuro-otological dysfunction being closely related to the disease burden and biomarkers like α-Gal A activity and lyso-Gb3.

Screening for Fabry disease in patients with hypertrophic cardiomyopathy using cardiac magnetic resonance imaging

BACKGROUND

Fabry disease (FD) usually mimics hypertrophic cardiomyopathy (HCM). Decreased native T1 mapping and a unique late gadolinium enhancement (LGE) pattern by cardiac magnetic resonance (CMR) imaging are specific imaging markers for FD.

PURPOSE

Explore the performance of multiparametric CMR imaging in screening for FD in patients with a HCM phenotype.

MATERIALS AND METHODS

A prospective cohort of 602 patients with a HCM phenotype was assessed from April 2012 to December 2022. Participants underwent CMR imaging and genetic testing. FD diagnosis was according to genetic testing and enzyme-activity test of α-galactosidase A. Multiparameter CMR imaging included cardiac function, native T1 mapping, extracellular volume (ECV), T2 mapping, LGE, and myocardial strains. Diagnostic performance of CMR parameters in identifying FD from HCM was done by analysis of receiver operating characteristic (ROC) curves.

RESULTS

FD prevalence was 1.8% (11 cases) in this cohort with HCM. Native T1 mapping was significantly lower in FD compared with HCM (FD vs. HCM: native T1 mapping: 1174.08 ± 60.60 vs. 1293.94 ± 55.86, p < 0.001). Ventricular function, mass, ventricular wall thickness, and strains did not show significant differences between the two groups. Binary logistic regression and analysis of ROC curves demonstrated myocardial native T1 mapping of the left ventricular basal slice had the best performance in screening for FD in patients with a HCM phenotype (cutoff: 1216 ms; AUC: 0.947; sensitivity: 91%; specificity: 90%).

CONCLUSION

Native T1 mapping is the best parameter for screening FD in a Chinese population with a HCM phenotype.

KEY POINTS

Question The prevalence of Fabry Disease (FD) in the study population is unknown and the efficacy of cardiac MRI (CMR) parameter screening for FD needs validating. Findings We report the prevalence of FD among a Chinese hypertrophic cardiomyopathy (HCM) cohort and found T1 mapping is the best CMR parameter for screening FD. Clinical relevance Native T1 mapping is the best CMR parameter for screening FD in the HCM cohort, providing an effective method for rapid screening of FD in clinic, which may help identify patients for early treatment of FD.

Screening for Fabry disease in patients with left ventricular hypertrophy in China: A multicentre and prospective study

AIMS

Left ventricular hypertrophy (LVH) is frequently detected via echocardiography in individuals with Fabry disease (FD), sometimes leading to confusion with hypertrophic cardiomyopathy (HCM) of other aetiologies. Considering this diagnosis challenge, FD should be included in the list of differential diagnosis for patients presenting with LVH. To address this concern, we conducted a prospective screening study in China, using dried blood spot (DBS) testing, to evaluate patients with unexplained LVH.

METHODS

Our study was designed as a nationwide, multicentre prospective investigation. A total of 1015 patients from 55 different centres who were diagnosed with LVH by echocardiography were screened in the study from September 2022 to December 2023. Demographic information, biochemistry data, echocardiography parameters and clinical observations were meticulously collected from all participants. The DBS method was used to assess α-galactosidase A (α-Gal A) activity in males and both α-Gal A and globotriaosylsphingosine (lyso-Gb3) levels in females.

RESULTS

The final screening population included 906 patients (589 males, 65%) with LVH, characterized by a mean maximal myocardial thickness of 14.8 ± 4.6 mm and an average age of 56.9 ± 17.2 years. In total, 43 patients (38 males, 5 females) exhibited low α-Gal A activity measurement (<2.2 μmol/L), while 21 patients (10 males, 11 females) presented low α-Gal A activity or elevated lyso-Gb3 levels (>1.1 ng/mL). Among these patients, eight individuals (7 males and 1 female) were genetically confirmed to harbour pathogenic GLA mutations, resulting in a total prevalence of 0.88%. Compared with patients without FD, patients with FD tended to have proteinuria (75% vs. 21.2%, P = 0.001), family history of HCM (37.5% vs. 2.3%, P < 0.01) and neuropathic pain (37.5% vs. 4.4%, P < 0.01) but lower systolic blood pressure (118.5 ± 12.5 vs. 143.3 ± 29.3 mmHg, P = 0.017). Five mutations were previously recognized as associated with FD while the remaining two, p.Asp313Val (c.938A>T) and c.547+3A>G, were deemed potentially pathogenic. Subsequent familial validation post-diagnosis identified an additional 14 confirmed cases.

CONCLUSIONS

This pioneering screening study for FD among Chinese patients with unexplained LVH using DBS measurement, revealed an FD detection rate of 0.88%. Our findings confirmed that the combined measurement of lyso-Gb3 and α-Gal A activity is beneficial for primary screening of FD in patients with LVH. Given the availability of efficacious therapies and the value of cascade screening in extended families, early detection of FD in LVH patients is clinically important.

Effectiveness and safety of enzyme replacement therapy in the treatment of Fabry disease: a Chinese monocentric real-world study

OBJECTIVE

To assess the effectiveness and safety of enzyme replacement therapy (ERT) for treating Fabry disease in clinical practice.

METHODS

The clinical data of patients with Fabry disease were retrospectively collected and screened according to inclusion and exclusion criteria. The effectiveness of ERT was evaluated by analyzing the improvement in renal dysfunction (decreased estimated glomerular filtration rate (eGFR) and proteinuria), cardiac system injury (mainly increased left ventricular mass index (LVMI)), and neuropathic pain after ERT treatment. The safety of ERT was measured by summarizing the occurrence of adverse events (AE) and adverse drug reactions (ADR) before and after ERT.

RESULTS

Sixteen patients with Fabry disease who underwent ERT treatment 2-36 times over a period of 2-89 weeks were enrolled in the study. Among them, 13 received symptomatic treatment based on the involvement of various organs, 14 were treated with anti-inflammatory and anti-allergic drugs, and 16 had no AE or ADR. After ERT, there was no significant difference in (eGFR, microalbumin (mALB), 24 h urinary protein quantitation (24 h PRO), urinary albumin/creatinine ratio (ACR), uric acid (UA), and β2 microglobulin (β2MG) (P > 0.05), and the renal function remained stable or improved; ERT could significantly reduce left ventricular mass index (LVMI) (P = 0.043) and lactate dehydrogenase (LDH) (P = 0.031), and other cardiac function indexes had an improvement trend or remained stable, but the difference was not significant (P > 0.05). After ERT, the degree of limb pain in three of the four minor patients improved.

CONCLUSIONS

ERT could effectively stabilize or improve renal and cardiac function and relieve neuropathic pain in patients with Fabry disease, and no AE occurred during treatment, and the clinical effectiveness and safety were satisfactory.

Septal Myectomy in Patients with Hypertrophic Cardiomyopathy and Nonclassical Anderson-Fabry Disease

Anderson-Fabry disease (AFD) results from decreased enzyme activity of lysosomal enzymes and intralysosomal storage of nonhydrolyzed forms. Cardiovascular complications, mainly in the form of HCM, contribute substantially to AFD patient mortality. Here, we report three new cases of obstructive HCM (HOCM) in nonclassical presentations of AFD and isolated cardiac involvement. In all three cases, the diagnosis of AFD was made postoperatively by routine genetic and morphological testing. Together with previously published cases, this report illustrates the potential safety and beneficial effect of septal surgical myectomy in patients with AFD-HOCM, as well as underlines the need for more thorough screening for clinical signs of AFD-associated cardiomyopathy and GLA variants among patients with HOCM.

The Asian Fabry Cardiomyopathy High-Risk Screening Study 2 (ASIAN-FAME-2): Prevalence of Fabry Disease in Patients with Left Ventricular Hypertrophy

Background: Fabry disease (FD) is a rare X-linked lysosomal storage disorder that commonly manifests cardiovascular complications. We aimed to assess the prevalence of FD in a Chinese population with left ventricular hypertrophy (LVH) whilst implementing a gender-specific screening approach. Methods: Patients with LVH, defined as a maximum thickness of the left ventricular septal/posterior wall ≥ 13 mm, were considered eligible. All patients with hypertrophic cardiomyopathy (HCM) were excluded. Plasma α-galactosidase (α-GLA) enzyme activity was assessed using a dried blood spot test. Males with low enzyme activity underwent genetic testing to confirm a diagnosis of FD whereas females were screened for both α-GLA and globotriaosylsphingosine concentration and underwent genetic analysis of the GLA gene only if testing positive for ≥1 parameter. Results: 426 unrelated patients (age = 64.6 ± 13.0 years; female: male = 113:313) were evaluated. FD was diagnosed in 3 unrelated patients (age = 69.0 ± 3.5 years, female: male = 1:2) and 1 related female subject (age = 43 years). Genetic analyses confirmed the late-onset cardiac variant GLA c.640-801G>A (n = 3) and the missense variant c.869T>C associated with classic FD (n = 1). Cardiac complications were the only significant findings associated with the late-onset c.640-801G>A mutation, manifesting as mild or severe concentric LVH. In contrast, the classic c.869T>C mutation FD exhibited multisystemic manifestations in addition to severe concentric LVH. Conclusions: The prevalence of FD is lower in Chinese patients with LVH when HCM is excluded. The pathological variant c.640-801G>A remains the most common cause of late-onset FD, while the detection of FD in females can be improved by utilizing a gender-specific screening method.

Accurate Classification of Non-ischemic Cardiomyopathy

PURPOSE OF REVIEW

This article aims to review the accurate classification of non-ischemic cardiomyopathy, including the methods, basis, subtype characteristics, and prognosis, especially the similarities and differences between different classifications.

RECENT FINDINGS

Non-ischemic cardiomyopathy refers to a myocardial disease that excludes coronary artery disease or ischemic injury and has a variety of etiologies and high incidence. Recent studies suggest that traditional classification methods based on primary/mixed/acquired or genetic/non-genetic cannot meet the precise needs of contemporary clinical management. This article systematically describes the history of classifications of cardiomyopathy and presents etiological and genetic differences between cardiomyopathies. The accurate classification is described from the perspective of morphology, function, and genomics in hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, left ventricular noncompaction, and partially acquired cardiomyopathy. The different clinical characteristics and treatment needs of these cardiomyopathies are elaborated. Some single-gene mutant cardiomyopathies have unique phenotypes, and some cardiomyopathies have mixed phenotypes. These special classifications require personalized precision treatment, which is worthy of independent research. This article describes recent advances in the accurate classification of non-ischemic cardiomyopathy from clinical phenotypes and causative genes, discusses the advantages and usage scenarios of each classification, compares the differences in prognosis and patient management needs of different subtypes, and summarizes common methods and new exploration directions for accurate classification.

The prevalence of Fabry disease among 1009 unrelated patients with hypertrophic cardiomyopathy: a Russian nationwide screening program using NGS technology

BACKGROUND

There is a vast number of screening studies described in the literature from the beginning of the twenty-first century to the present day. Many of these studies are related to the estimation of Fabry disease (FD) morbidity among patients from high-risk groups, including adult patients with hypertrophic cardiomyopathy (HCM) and left ventricular hypertrophy (LVH). These studies show diverse detection frequencies (0-12%) depending on the methodology. Our study is the only example of large-scale selective FD screening based on the implementation of next-generation sequencing technology (NGS) as a first-level test to estimate FD morbidity in the Russian population over 18 years of age burdened with HCM.

METHODS

The study included 1009 patients (578 males and 431 females), with a median age of 50 years, who were diagnosed with HCM according to current clinical guidelines. In the first stage of screening, all patients underwent molecular genetic testing (NGS method) of target regions. These regions included the coding sequences of 17 genes and mutations that can lead to the development of HCM. Lysosomal globotriaosylsphingosine (lyso-Gb3) concentrations and α-galactosidase A (α-gal A) enzyme activity were measured in the second stage of screening to reveal pathogenic or likely pathogenic variants in the GLA gene.

RESULTS

We revealed 8 (0.8%) patients (3 (37.5%) males and 5 (62.5%) females) with an average age of 59 ± 13.3 years who had pathogenic, likely pathogenic variants and variants of uncertain significance (VUS) in the GLA gene (NM_000169.2) as a result of selective screening of 1009 Russian patients with HCM. FD was confirmed via biochemical tests in a male with the pathogenic variant c.902G > A, p.R301Q as well as in two females with likely pathogenic variants c.897C > A, p.D299E and c.1287_1288dup, p.*430Fext*?. These tests showed reduced enzymatic activity and increased substrate concentration. However, a female with the pathogenic variant c.416A > G, p.N139S and with normal enzymatic activity only had increased substrate concentrations. The revealed nucleotide variants and high values of biochemical indicators (lyso-Gb3) in these 4 patients allowed us to estimate the FD diagnosis among 1009 Russian patients with HCM. Mild extracardiac manifestations were observed in these four patients; however, both biochemical values within the reference range in females with the c.971T > G, p.L324W (VUS) variant. α-gal A activity and lyso-Gb3 concentrations were also within the normal range in two males with hemizygous variants, c.546T > C, p.D182D and c.640-794_640-791del (we regarded them as VUS), and in one female with the c.427G > A, p.A143T variant (with conflicting interpretations of pathogenicity).

CONCLUSION

The prevalence rate of FD among 1,009 adult Russian patients with HCM was 0.4%. We recommend FD screening among adult patients of both sexes with HCM and an undefined genetic cause via NGS method with subsequent analysis of α-gal A activity and lyso-Gb3 concentration in patients with pathogenic, likely pathogenic variants, and VUS. This strategy identifies patients with an atypical form of FD that is characterized by high residual activity of α-gal A, low concentrations of lyso-Gb3, and minor extracardiac manifestations.