D313Y Variant in Fabry Disease: A Systematic Review and Meta-analysis

Prevalence of Fabry disease in patients with left ventricular hypertrophy and renal involvement (PrEFaCe)

INTRODUCTION AND AIMS

Fabry disease (FD) causes glycosphingolipid accumulation in the vascular endothelium, with predominantly cardiac and renal involvement. Its prevalence in patients with concomitant involvement of these two organs is unknown. The objective of the study was to determine the prevalence of FD in patients with left ventricular hypertrophy and any degree of chronic kidney disease.

PATIENTS AND METHODS

Patients with ventricular thickness ≥13mm and kidney disease from 29 Spanish hospitals were included. Sociodemographic variables and target organ involvement of FD were collected. Laboratory determinations of EF were carried out, with an enzymatic activity test±genetic test in men and direct genetic test in women.

RESULTS

Eight hundred ninety-eight patients with left ventricular hypertrophy and chronic kidney disease were included. The presence of heart failure and cardiorenal syndrome was common (46.1% and 40.1%). Three patients (2 men and 1 woman) were diagnosed with FD, based on the presence of a pathogenic variant in the GLA gene and classic signs of FD, resulting in a prevalence of 0.33% (CI 95% 0.06-1%). Six patients (0.66%) presented genetic variants of unknown significance, without showing classic signs of FD, while in 13 patients (3.2%) performing the blood test was impossible.

CONCLUSIONS

FD is an important cause of left ventricular hypertrophy and chronic kidney disease. Genetic diagnosis is crucial for avoiding biases and ensuring accurate identification of FD, especially in women. The results support the inclusion of this disease in the differential diagnosis of patients with ventricular hypertrophy ≥13mm and chronic kidney disease.

Uncovering genetic mimics in multiple sclerosis: A single-center clinical exome sequencing study

Background

Multiple sclerosis (MS) shares clinical/radiological features with several monogenic diseases that can mimic MS.

Objective

We aimed to determine if exome sequencing can identify monogenic diseases in patients diagnosed with MS according to the McDonald criteria thus uncovering them as being misdiagnosed.

Methods

We performed whole exome sequencing in a cohort of 278 patients with MS, clinically or radiologically isolated syndrome without cerebrospinal fluid-specific oligoclonal bands (CSF-OCBs) (n = 228), a positive family history of MS (n = 44), or both (n = 6), thereby focusing on individuals potentially more likely to have underlying monogenic conditions mimicking MS. We prioritized 495 genes associated with monogenic diseases sharing features with MS.

Results

A disease-causing variant in NOTCH3 was identified in one patient without CSF-OCBs, no spinal lesions, with non-response to immunotherapy, and a family history of dementia, thereby converting the diagnosis to cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Moreover, 18 patients (6.5% of total) carried variants of unclear significance.

Conclusion

Monogenic diseases being misdiagnosed as MS seem rare in patients diagnosed with MS according to the McDonald criteria, even in CSF-OCB negative cases. The detected pathogenic NOTCH3 variant emphasizes CADASIL as a rare differential diagnosis and highlights the relevance of genetic testing in selected MS cases with atypical presentations.

Prevalence of Fabry disease and GLA variants in young patients with acute stroke: The challenge to widen the screening. The Fabry-Stroke Italian Registry

BACKGROUND

Fabry disease (FD) is a treatable X-linked lysosomal storage disorder caused by GLA gene variants leading to alpha-galactosidase A deficiency. FD is a rare cause of stroke, and it is still controversial whether in stroke patients FD should be searched from the beginning or at the end of the diagnostic workup (in cryptogenic strokes).

METHODS

Fabry-Stroke Italian Registry is a prospective, multicentric screening involving 33 stroke units. FD was sought by measuring α-galactosidase A activity (males) and by genetic tests (males with reduced enzyme activity and females) in patients aged 18-60 years hospitalized for TIA, ischemic stroke, or intracerebral hemorrhage. We diagnosed FD in patients with 1) already known pathogenic GLA variants; 2) novel GLA variants if additional clinical, laboratory, or family-derived criteria were present.

RESULTS

Out of 1906 patients, we found a GLA variant in 15 (0.79%; 95%CI 0.44-1.29) with a certain FD diagnosis in 3 (0.16%; 95%CI 0.03-0.46) patients, none of whom had hemorrhage. We identified 1 novel pathogenic GLA variant. Ischemic stroke etiologies in carriers of GLA variants were: cardioaortic embolism (33%), small artery occlusion (27%), other causes (20%), and undetermined (20%). Mild severity, recurrence, previous TIA, acroparesthesias, hearing loss, and small artery occlusion were predictors of GLA variant.

CONCLUSION

In this large multicenter cohort the frequency of FD and GLA variants was consistent with previous reports. Limiting the screening for GLA variants to patients with cryptogenic stroke may miss up to 80% of diagnoses. Some easily recognizable clinical features could help select patients for FD screening.

Missed diagnosis of Fabry disease: should we screen patients with multiple sclerosis?

INTRODUCTION

Fabry disease (FD) can be undiagnosed in the context of multiple sclerosis (MS) due to similar clinical and paraclinical features. Our study aimed to determine the prevalence (and the necessity of screening) of FD among patients with possible or definite MS.

METHODS

In this prospective monocentric observational study, we included consecutive patients enrolled between May 2017 and May 2019 after the first clinical event suggestive of MS. All patients underwent FD screening using dried blood spots in a stepwise manner combining genetic and enzyme testing. Patients were followed until May 2022.

RESULTS

We included 160 patients (73.1% female, mean age 33.9 years). The 2017 revised McDonald's criteria for definite MS were fulfilled by 74 (46.3%) patients at the time of study recruitment and 89 (55.6%) patients after 3-5 years of follow-up. None of the patients had a pathogenic GLA variant, and four (2.5%) had a variant of unknown significance (p.A143T, p.S126G, 2 × p.D313Y). In two of these patients, the intrathecal synthesis of oligoclonal bands was absent, and none had hyperproteinorachia or pleocytosis in cerebrospinal fluid. Detailed examination of FD organ manifestations revealed only discrete ocular and kidney involvement in two patients.

CONCLUSION

The prevalence of FD in the population of suspected or definite MS patients does not appear to be high. Our results do not support routine FD screening in all patients with a possible diagnosis of MS, but there is an urgent need to search for red flags and include FD in the differential diagnosis of MS.

Clinical significance of small nerve fiber involvement in the early diagnosis and treatment of patients with Fabry disease

INTRODUCTION

Peripheral nervous system is early involved in Fabry disease (FD) and preferentially the small nerve fibers, causing the characteristic neuropathic pain crises usually beginning in childhood. Early detection of this likely underdiagnosed disease is an important approach because causal therapies are available.

METHODS

We conducted a case-series study to investigate the small nerve fiber involvement in FD and its contribution to the diagnosis of the disease but also to the timely effective therapy administration. We used specific structured scales of symptoms and signs to detect peripheral neuropathy, as well as suitable functional and structural tests to diagnose the small fiber neuropathy (SFN).

RESULTS

Twenty-seven consecutive patients (14 men, mean age 44.62 ± 10.70 years) with suspected FD were included in this study. Most of the patients presented symptoms of small nerve fiber involvement, which were accompanied by abnormal test results, fulfilling the criteria for SFN. The detection of SFN in our patients allowed the completion of the FD diagnostic criteria and thus the initiation of therapy. In five patients the SFN diagnosis determined the administration of therapy, whereas in two others it might be considered.

CONCLUSION

Our results further suggest the importance of early diagnosis of peripheral neuropathy, especially of small nerve fiber involvement, in patients with suspected FD as it contributes crucially not only to the diagnosis but also to the timely effective initiation of FD therapy.