FabryScan: a screening tool for early detection of Fabry disease

Cold-evoked potentials in Fabry disease and polyneuropathy

Background

Fabry disease (FD) causes cold-evoked pain and impaired cold perception through small fiber damage, which also occurs in polyneuropathies (PNP) of other origins. The integrity of thinly myelinated fibers and the spinothalamic tract is assessable by cold-evoked potentials (CEPs). In this study, we aimed to assess the clinical value of CEP by investigating its associations with pain, autonomic measures, sensory loss, and neuropathic signs.

Methods

CEPs were examined at the hand and foot dorsum of patients with FD (n = 16) and PNP (n = 21) and healthy controls (n = 23). Sensory phenotyping was performed using quantitative sensory testing (QST). The painDETECT questionnaire (PDQ), FabryScan, and measures for the autonomic nervous system were applied. Group comparisons and correlation analyses were performed.

Results

CEPs of 87.5% of the FD and 85.7% of the PNP patients were eligible for statistical analysis. In all patients combined, CEP data correlated significantly with cold detection loss, PDQ items, pain, and autonomic measures. Abnormal CEP latency in FD patients was associated with an abnormal heart frequency variability item (r = -0.684; adjusted p = 0.04). In PNP patients, CEP latency correlated significantly with PDQ items, and CEP amplitude correlated with autonomic measures (r = 0.688, adjusted p = 0.008; r = 0.619, adjusted p = 0.024). Furthermore, mechanical pain thresholds differed significantly between FD (gain range) and PNP patients (loss range) (p = 0.01).

Conclusions

Abnormal CEPs were associated with current pain, neuropathic signs and symptoms, and an abnormal function of the autonomic nervous system. The latter has not been mirrored by QST parameters. Therefore, CEPs appear to deliver a wider spectrum of information on the sensory nervous system than QST alone.

Screening for health-related quality of life and its determinants in Fabry disease: A cross-sectional multicenter study

BACKGROUND

Fabry disease (FD) is a rare X-linked lysosomal storage disorder caused by α-galactosidase A (α-Gal A) deficiency. The progressive accumulation of globotriaosylceramide results in life-threatening complications, including renal, cardiac, and cerebrovascular diseases. In order to improve health care of FD-patients, knowledge of its predictors is important. The aim of our study was to evaluate health-related quality of life (HrQol) in FD and to identify its independent determinants by exploring a wide range of demographic, social and clinical parameters.

RESULTS

In this cross-sectional multicenter study, 135 adult patients with FD were recruited at three specialized European centers in Germany and Switzerland. Demographics, social status and clinical parameters as well as data on HrQol (EQ5D, EQ VAS) and depression were collected by means of self-reporting questionnaires and confirmed by medical records. HrQol and its predictors were evaluated by univariate and multivariate regression analyses. The study population consisted of 78 female and 57 male FD patients (median age 48 yrs) of whom 80.7% (N = 109) were on enzyme replacement therapy (ERT) and 10.4% (N = 14) were on chaperone treatment. Univariate analysis revealed various factors reducing HrQol such as age > 40 years, classic phenotype, organ involvement (kidney and heart disease, stroke/transient ischemic attack (TIA), gastrointestinal disturbances), depression, and burning limb pain. However, only the following factors were identified as independent predictors of decreased HrQol: classic phenotype, kidney and heart disease, stroke/TIA, depression, and burning limb pain. ERT and chaperone therapy were independent determinants of increased HrQol.

CONCLUSIONS

Modifiable factors, such as burning limb pain and depression, identified as independent predictors of HrQol-deterioration should be addressed in programs aiming to improve HrQol in FD. A multidisciplinary approach is essential in FD-patients since diverse organ involvement prominently compromises HrQol in affected patients. Our findings showed that the classic phenotype is a strong predictor of worsening HrQol.

Unusual Pain Disorders - What Can Be Learned from Them?

Pain is common in many different disorders and leads to a significant reduction in quality of life in the affected patients. Current treatment options are limited and often result in insufficient pain relief, partly due to the incomplete understanding of the underlying pathophysiological mechanisms. The identification of these pathomechanisms is therefore a central object of current research. There are also a number of rare pain diseases, that are generally little known and often undiagnosed, but whose correct diagnosis and examination can help to improve the management of pain disorders in general. In some of these unusual pain disorders like sodium-channelopathies or sensory modulation disorder the underlying pathophysiological mechanisms have only recently been unravelled. These mechanisms might serve as pharmacological targets that may also play a role in subgroups of other, more common pain diseases. In other unusual pain disorders, the identification of pathomechanisms has already led to the development of new drugs. A completely new therapeutic approach, the gene silencing, can even stop progression in hereditary transthyretin amyloidosis and porphyria, ie in pain diseases that would otherwise be rapidly fatal if left untreated. Thus, pain therapists and researchers should be aware of these rare and unusual pain disorders as they offer the unique opportunity to study mechanisms, identify new druggable targets and finally because early diagnosis might save many patient lives.

When and How to Diagnose Fabry Disease in Clinical Pratice

Fabry disease is a frequent lysosomal storage disorder secondary to the deficiency of alpha-galactosidase A enzyme. This X-linked genetic disease realizes progressive and systemic manifestations that affect both male and female. Fabry disease may present as "classical", as "late-onset" or "non-classical" forms. Symptoms and organ involvements of classical Fabry disease are acral pain crisis, cornea verticillata, hypertrophic cardiomyopathy, stroke and chronic kidney disease with proteinuria. Other common symptoms are often poorly recognized, such as gastrointestinal or ear involvements. In classical Fabry disease, symptoms first appear during childhood or during teenage years in males, but later in females. Patients with non-classical or late-onset Fabry disease have delayed manifestations or a single-organ involvement. Diagnosis is therefore difficult when classical organ involvements are missing, in paucisymptomatic patients or in late-onset forms. Recognition of Fabry disease is important because effective treatments are available. They have to be prescribed early. In male, diagnosis is made with alpha-galactosidase A enzyme activity dosage in leukocyte, that is very low or null in classical forms and under 30 percent in late-onset forms. Diagnosis is more challenging in females who may express normal residual enzyme activity. Other plasmatic biomarkers, such as lyso-globotriaosylceramide are interesting, especially in females. In this review, we aimed to summarize main clinical manifestations of Fabry disease to know when to evoke Fabry disease and propose a practical diagnosis algorithm to know how to diagnose.

Stratification of patients with unclassified pain in the FabryScan database

Purpose

Fabry disease belongs to lysosomal storage disorders and can be successfully treated today. On the contrary, the correct diagnostic classification of its symptoms can be challenging and most patients suffer from pain for years, until they are diagnosed correctly. The aim of this project was to characterize patients with unclassified extremity pain and to present a simple algorithm for a retrospective stratification approach.

Patients and methods

The FabryScan includes a bedside-test and a questionnaire, consisting of 10 symptom-orientated and anamnestic questions. For the stratification of patients according to the likelihood for Fabry disease two different approaches were conducted. First, a prospective subgrouping based on the previously invented FabryScan evaluation system was conducted. The second retrospective approach consisted of a factor analysis and a subsequent two-way cluster analysis. Further on, 4 patients diagnosed with Fabry disease were stratified according to both approaches.

Results

In total, 183 completed datasets were included in the statistical analysis. The first approach prospectively classified patients into 3 subgroups (n=40 [likely], n=96 [possible], n=47 [unlikely]) according to the FabryScan evaluation system. The second approach retrospectively stratified patients into 3 subgroups (n=47 [cluster 1], n=95 [cluster 2], n=41 [cluster 3]). Finally, the Fabry patients were sorted to the subgroups, indicative for the highest possibility of Fabry disease in both stratification approaches A and B.

Conclusion

Both stratification approaches sorted patients with confirmed Fabry disease to the subgroups, indicative for the highest likelihood for Fabry. These results indicate validity of the initially selected FabryScan outcome parameters.

European expert consensus statement on therapeutic goals in Fabry disease

BACKGROUND

Fabry disease, an inherited lysosomal storage disorder, causes multi-organ pathology resulting in substantial morbidity and a reduced life expectancy. Although Fabry disease is an X-linked disorder, both genders may be affected, but generally to a lesser extent in females. The disease spectrum ranges from classic early-onset disease to non-classic later-onset phenotypes, with complications occurring in multiple organs or being confined to a single organ system depending on the stage of the disease. The impact of therapy depends upon patient- and disease-specific factors and timing of initiation.

METHODS

A European panel of experts collaborated to develop a set of organ-specific therapeutic goals for Fabry disease, based on evidence identified in a recent systematic literature review and consensus opinion.

RESULTS

A series of organ-specific treatment goals were developed. For each organ system, optimal treatment strategies accounted for inter-patient differences in disease severity, natural history, and treatment responses as well as the negative burden of therapy and the importance of multidisciplinary care. The consensus therapeutic goals and proposed patient management algorithm take into account the need for early disease-specific therapy to delay or slow the progression of disease as well as non-specific adjunctive therapies that prevent or treat the effects of organ damage on quality of life and long-term prognosis.

CONCLUSIONS

These consensus recommendations help advance Fabry disease management by considering the balance between anticipated clinical benefits and potential therapy-related challenges in order to facilitate individualized treatment, optimize patient care and improve quality of life.

Fabry disease; early diagnosis improves prognosis but diagnosis is often delayed

Background:

Fabry disease (FD) is a rare X-linked deficiency of lysosomal enzyme alpha-galactosidase (AGAL) resulting in accumulation of globotriaosylceramide (Gb-3) in the cells, with protean manifestations. Major organs affected are the kidneys, heart and nervous system. The diagnosis of FD is often delayed by many years. Enzyme replacement started early might reverse the organ damage while delayed initiation may only stabilize the disease progression.

Case Presentation:

We describe a patient in whom involvement of different organs unfolded at different times and a detailed review of history by the clinician led to the diagnosis. The importance of electron microscopy (EM) of renal biopsy is highlighted.

Conclusions:

Patients with FD are often diagnosed late because the manifestations can be variable and spread over different time periods. Detailed history including family history and examining the renal biopsy by EM are crucial for early diagnosis.

Pain in Fabry Disease: Practical Recommendations for Diagnosis and Treatment

Aims

Patients with Fabry disease (FD) characteristically develop peripheral neuropathy at an early age, with pain being a crucial symptom of underlying pathology. However, the diagnosis of pain is challenging due to the heterogeneous and nonspecific symptoms. Practical guidance on the diagnosis and management of pain in FD is needed.

Methods

In 2014, experts met to discuss recent advances on this topic and update clinical guidance.

Results

Emerging disease‐specific tools, including FabryScan, Fabry‐specific Pediatric Health and Pain Questionnaire, and Würzburg Fabry Pain Questionnaire, and more general tools like the Total Symptom Score can aid diagnosis, characterization, and monitoring of pain in patients with FD. These tools can be complemented by more objective and quantifiable sensory testing. In male and female patients of any age, pain related to FD can be an early indication to start disease‐specific enzyme replacement therapy before potentially irreversible organ damage to the kidneys, heart, or brain occurs.

Conclusion

To improve treatment outcomes, pain should be diagnosed early in unrecognized or newly identified FD patients. Treatment should include: (a) enzyme replacement therapy controlling the progression of underlying pathology; (b) adjunctive, symptomatic pain management with analgesics for chronic neuropathic and acute nociceptive, and inflammatory or mixed pain; and (c) lifestyle modifications.

Characterization of pain in fabry disease

OBJECTIVE

To give a detailed characterization of pain in a large cohort of patients with Fabry disease.

PATIENTS AND METHODS

In this single-center, retrospective study we performed a detailed analysis of pain prevalence and characteristics of 132 patients with Fabry disease. Data were obtained by screening all medical records and using standardized extraction forms. Missing data were completed by telephone interviews.

RESULTS

We show that men and women with Fabry disease frequently experience pain, mostly starting in early childhood. Pain is typically episodic with pain attacks being the predominant phenotype. The most frequent localization is in the distal extremities, the most often named pain quality is "burning." Fabry pain is triggerable by physical activity and thermal stimuli and improves over time. Frequently used acute pain medication consists of nonsteroidal antirheumatics and nonopioid analgesics. Long-term medications such as drugs used to treat neuropathic pain syndromes are rarely taken by Fabry patients.

CONCLUSIONS

Pain in Fabry disease affects both sexes and has a complex phenotype that requires comprehensive assessment. Current pain questionnaires fail to cover the entire scope of Fabry pain. Although basically neuropathic, some types of Fabry pain may respond to nonsteroidal antirheumatics and nonopioid analgesics.

Fabry disease: a rare cause of neuropathic pain

Fabry disease is characterized by burning or shooting pains in hands and feet, which have a severe impact on the quality of life of patients. It is therefore of importance that Fabry patients receive adequate diagnosis, counseling, treatment and follow up. This review describes neuropathic pain in classical Fabry disease with the aim to help clinicians to recognize Fabry patients among patients presenting with chronic extremity pain. The diagnostic dilemmas in patients with neuropathic pain and a non-classical disease course are discussed, together with the available diagnostic modalities, pain medication options and the effect of enzyme replacement therapy on small fiber neuropathy.