New biomarkers defining a novel early stage of Fabry nephropathy: A diagnostic test study

Health-related quality of life in Norwegian adults with Fabry disease: Disease severity, pain, fatigue and psychological distress

Health-related quality of life (HRQOL) is reduced in Fabry disease (FD) and associated with clinical disease manifestations, but few have used Fabry-specific severity scores to study how disease burden interferes with quality of life. We investigated how the Fabry DS3, consisting of four somatic domains and one patient-reported item, associates with HRQOL, while also evaluating fatigue, pain and psychological distress as possible predictors. Thirty-six adults with FD completed the Short-form Health Survey (SF-36), the hospital anxiety and depression scale (HADS), the brief pain inventory (BPI) and reported fatigue on a visual analog scale. Clinical data were collected from the last multidisciplinary hospital visit. Using correlation and hierarchical linear regression analyses, we examined associations between demographic, clinical and self-reported predictors and the SF-36 physical (PCS) and mental (MCS) component summary scores. Males scored lower than the general population in all SF-36 domains (P < .05). General health and social functioning were reduced in females. Before including self-reported symptom scores, DS3 showed associations with PCS (P = .009). Our fully adjusted model explained 66% of the variation in PCS, where education (P = .040) and fatigue (P = .002) retained significance. With HADS depression score (P = .001) as the sole significant factor, our regression model explained 56% of the variation in MCS. The DS3 score has implications for HRQOL in FD. Low education and fatigue represent major barriers to physical well-being, while depression strongly influences mental quality of life. Fatigue should be recognized as an important endpoint in future FD trials. Increased efforts to diagnose and treat affective disorders are warranted.

The impact of demographic and clinical characteristics on the trajectories of health-related quality of life among patients with Fabry disease

Background

Fabry disease (FD) is an X-linked lysosomal storage disorder characterized by multiorgan dysfunction. Since individuals with FD usually experience progressive clinical disease manifestations, their health-related quality of life (HRQOL) is expected to change over time. However, there is limited longitudinal research examining HRQOL outcomes in individuals with FD. We aimed to: assess longitudinal outcomes in HRQOL in adults with FD; examine the physical- and mental HRQOL trajectories at the initial registration (baseline), 3–5 year, and 7–13 year follow-ups; and evaluate the possible associations of age, sex and medical complications with the physical- and mental HRQOL trajectories.

Methods

Forty-three individuals with FD (53% female) who were aged 18 to 81 years at baseline attended clinical follow-up visits between 2006 and 2020. Medical records were extracted retrospectively. Demographics and the 36-item Short-Form Health Survey (SF-36) were recorded at scheduled visits, except for the last data collection which was prospectively obtained in 2020. The physical (PCS) and mental (MCS) composite scores (SF-36) were chosen as outcome measures.

Results

The eight SF-36 domain scores were stable over a span of 13 years, and only physical- and social functioning domains worsened clinically over this follow-up period. Mean baseline SF-36 domain scores were all significantly lower (decreased HRQOL) in the FD sample compared with Norwegian population norms. Two hierarchical linear models were run to examine whether demographics and medical complications (measured at the last clinical visit) predicted physical and mental HRQOL trajectories. Age above 47 years (p < 0.001), male sex (p = 0.027), small fibre neuropathy (p < 0.001), renal dysfunction (p < 0.001), and cerebrovascular events (p = 0.003) were associated with lower HRQOL over time. No significant interactions were found between the time of follow up and the abovementioned predictors of HRQOL.

Conclusions

Overall HRQOL trajectories remained stable between baseline, 3–5 year, and 7–13 year follow-ups, with the majority of individuals reporting decreased physical and mental HRQOL. Medical complications in combination with older age and male sex are important predictors of lower HRQOL in FD. Awareness of this relationship is valuable both for health care providers and for patients. The findings provide indicators that can guide treatment decisions to improve physical and mental HRQOL outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-02066-y.

Renal Manifestations of Fabry Disease: A Narrative Review

Purpose of review

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

Source of information

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

Methods

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

Key findings

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

Limitations

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

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.

Direct Correlation between Age at Diagnosis and Severity of Nephropathy in Fabry Disease Patients

INTRODUCTION

Nephropathy is one of the major complications of Fabry disease and mainly includes reduced glomerular filtration rate and proteinuria. Affected patients show different degrees of annual loss of renal function according to the magnitude of proteinuria and decrease in estimated glomerular filtration rate (eGFR) at the baseline.

OBJETIVE

To analyze the relationship between age at diagnosis and severity of nephropathy in a Fabry disease population.

METHODS

Cross-sectional design with retrospective data collection.

RESULTS

Seventy-two patients were studied with mean age of 26.26 ± 16.48 years and 30 men (41.6%). Twenty-seven paediatric patients and 45 adults were included. Thirteen genotypes were found: E398X, L415P, c886A>G, L106R, c.680G>A, A292T, c. 448.delG, R363H, C382Y, R301Q, D109G, del 3 and 4 exons, W81X, all pathogenic mutations of GLA gene. The mean eGFR in paediatric population was 115.81 ± 20.87 ml/min/1.73 m2 and in adults was 80.63 ± 42.22 ml/min/1.73 m2. The Pearson's bilateral correlation coefficient test (value = -0.462) between the age at diagnosis and eGFR indicates inverse correlation between both variables with a strong statistical significance (P = < 0.01). Spearman's bilateral correlation coefficient (value = +0.385) between the variables at diagnosis and the degree of proteinuria indicates direct correlation between both variables with a strong statistical significance (P = <0.01).

CONCLUSIONS

Diagnosis of Fabry disease patients at a younger age could be a key to improve the nephropathy prognosis and allow early and effective interventions.

Fabry nephropathy. Role of nephrologist and clinical variables associated with the diagnosis

BACKGROUND

The early detection of Fabry nephropathy is of interest to us. Its treatment is more effective in early stages. It has been studied by analysing molecular and tissue biomarkers. These have certain disadvantages that hinder its routine use. The aim of this study is to describe the role of the nephrologist in the diagnosis of the disease, and to describe the clinical variables associated with nephropathy in affected patients.

MATERIAL AND METHODS

Cross-sectional study. Patients were included from three reference centres in Argentina.

RESULTS

Seventy two patients were studied (26.26±16.48years): 30 of which (41.6%) were men and 42 of which (58.4%) were women; 27 paediatric patients and 45 adults. Fourteen "index cases" were detected, 50% of which were diagnosed by nephrologists. Nephropathy was found in 44 patients (61%): 6 paediatric patients and 38 adults. Two types of clinical variables were associated with nephropathy: (i)peripheral nervous system compromise (P≤.001), angiokeratomas (P≤.001) and auditory compromise (P=.01-.001), with these being early clinical manifestations of the most severe disease phenotype, and (ii)structural heart disease (P=.01-.001) and central nervous system compromise (P=.05-.01), which are major and late complications, responsible for increased morbidity and mortality and lower life expectancy.

CONCLUSION

The nephrologist plays an important role in the diagnosis of Fabry nephropathy, although the detection thereof owing to its renal involvement would represent a late diagnosis, because nephropathy is associated with late complications of the most severe disease phenotype.

Multiple phenotypic domains of Fabry disease and their relevance for establishing genotype- phenotype correlations

Fabry disease (FD) is a rare X-linked glycosphingolipidosis resulting from deficient α-galactosidase A (AGAL) activity, caused by pathogenic mutations in the GLA gene. In males, the multisystemic involvement and the severity of tissue injury are critically dependent on the level of AGAL residual enzyme activity (REA) and on the metabolic load of the disease, but organ susceptibility to damage varies widely, with heart appearing as the most vulnerable to storage pathology, even with relatively high REA. The expression of FD can be conceived as a multidomain phenotype, where each of the component domains is the laboratory or clinical expression of the causative GLA mutation along a complex pathophysiologic cascade pathway. The AGAL enzyme activity is the most clinically useful marker of the protein phenotype. The metabolic phenotype and the pathologic phenotype are diverse expressions of the storage pathology, respectively, assessed by biochemical and histological/ultrastructural methods. The storage phenotypes are the direct consequences of enzyme deficiency and hence, together with the enzymatic phenotype, constitute the more specific diagnostic markers of FD. In the pathophysiology cascade, the clinical phenotypes are most distantly linked to the underlying genetic causation, being critically influenced by the patients’ gender and age, and modulated by the effects of variation in other genetic loci, of polygenic inheritance and of environmental risk factors. A major challenge in the clinical phenotyping of patients with FD is the differential diagnosis between its nonspecific, later-onset complications, particularly the cerebrovascular, cardiac and renal, and similar chronic illnesses that are common in the general population. Comprehensive phenotyping, whenever possible performed in hemizygous males, is therefore crucial for grading the severity of pathogenic GLA variants, to clarify the phenotypic correlations of hypomorphic alleles, to define benign polymorphisms, as well as to establish the pathogenicity of variants of uncertain significance.