Outcomes and management of kidney transplant recipients with Fabry disease: a review

Fabry disease is an X-linked inheritable lysosomal storage disease caused by various mutations of the galactosidase α gene resulting in α-galactosidase deficiency. Chronic kidney disease (CKD) is one of the most significant consequences of Fabry disease, with risk of end-stage kidney disease (ESKD) in this population. Like for other patients with ESKD, kidney transplant is the optimal treatment for Fabry disease patients with ESKD. However, enzyme replacement therapy and newer Fabry disease treatments remain important to mitigate other end organ damage such as cardiomyopathy post transplantation. This review is a primer on Fabry disease, which examines the outcomes of disease in the context of kidney transplant prior to, and during, the enzyme replacement treatment era, medical treatment of kidney transplant recipients with Fabry disease, and progress in screening studies.

Fabry Disease in Women: Genetic Basis, Available Biomarkers, and Clinical Manifestations

Fabry Disease (FD) is a rare lysosomal storage disorder caused by mutations in the GLA gene on the X chromosome, leading to a deficiency in α-galactosidase A (AGAL) enzyme activity. This leads to the accumulation of glycosphingolipids, primarily globotriaosylceramide (Gb3), in vital organs such as the kidneys, heart, and nervous system. While FD was initially considered predominantly affecting males, recent studies have uncovered that heterozygous Fabry women, carrying a single mutated GLA gene, can manifest a wide array of clinical symptoms, challenging the notion of asymptomatic carriers. The mechanisms underlying the diverse clinical manifestations in females remain not fully understood due to X-chromosome inactivation (XCI). XCI also known as "lyonization", involves the random inactivation of one of the two X chromosomes. This process is considered a potential factor influencing phenotypic variation. This review delves into the complex landscape of FD in women, discussing its genetic basis, the available biomarkers, clinical manifestations, and the potential impact of XCI on disease severity. Additionally, it highlights the challenges faced by heterozygous Fabry women, both in terms of their disease burden and interactions with healthcare professionals. Current treatment options, including enzyme replacement therapy, are discussed, along with the need for healthcare providers to be well-informed about FD in women, ultimately contributing to improved patient care and quality of life.

Twenty years of the Fabry Outcome Survey (FOS): insights, achievements, and lessons learned from a global patient registry

Background

Patient registries provide long-term, real-world evidence that aids the understanding of the natural history and progression of disease, and the effects of treatment on large patient populations with rare diseases. The year 2021 marks the 20th anniversary of the Fabry Outcome Survey (FOS), an international, multicenter, observational registry (NCT03289065). The primary aims of FOS are to broaden the understanding of Fabry disease (FD), an X-linked lysosomal storage disorder, and to improve the clinical management of affected patients. Here, we review the history of FOS and the analyses and publications disseminated from the registry, and we discuss the contributions FOS studies have made in understanding FD.

Results

FOS was initiated in April 2001 and, as of January 2021, 4484 patients with a confirmed diagnosis and patient informed consent have been enrolled from 144 centers across 26 countries. Data from FOS have been published in nearly 60 manuscripts on a wide variety of topics relevant to FD. Analyses of FOS data have investigated the long-term effectiveness and safety of enzyme replacement therapy (ERT) with agalsidase alfa and its effects on morbidity and mortality, as well as the benefits of prompt and early treatment with agalsidase alfa on the progression of cardiomyopathy and the decline in renal function associated with FD. Based on analyses of FOS data, ERT with agalsidase alfa has also been shown to improve additional signs and symptoms of FD experienced by patients. FOS data analyses have provided a better understanding of the natural history of FD and the specific populations of women, children, and the elderly, and have provided practical tools for the study of FD. FOS has also provided methodology and criteria for assessing disease severity which contributed to the continuous development of medical practice in FD and has largely improved our understanding of the challenges and needs of long-term data collection in rare diseases, aiding in future rare disease real-world evidence studies.

Conclusion

FOS over the last 20 years has substantially increased the scientific knowledge around improved patient management of FD and continues to expand our understanding of this rare disease.

Biomarkers associated with clinical manifestations in Fabry disease patients with a late-onset cardiac variant mutation

BACKGROUND

Fabry disease is a lysosomal storage disorder with an incidence of 1:1600 for the late-onset IVS4+919G>A cardiac variant mutation in Taiwan. Signs and symptoms of this cardiac variant include left ventricular hypertrophy, mitral insufficiency and/or arrhythmias. The search for biomarkers that might predict the clinical outcomes and guide treatment options is important. We thus investigated relationships between Fabry disease biomarkers (such as globotriaosylceramide (Gb₃), globotriaosylsphingosine (lyso-Gb₃)/related analogues) and age, gender, enzyme activity, clinical manifestations and severity of the disease in these patients.

METHOD

Urine and plasma biomarkers were analyzed using tandem mass spectrometry. A large cohort of 191 adult and pediatric Fabry patients carrying the IVS4+919G>A mutation was studied. Some patients were members of the same family.

RESULTS

Our results show that the plasma lyso-Gb₃ level, and urinary analogue levels of lyso-Gb₃ at m/z (+16), (+34), and (+50) adjusted for gender and age had a positive association with the left ventricular mass index, and/or the Mainz Severity Score Index.

CONCLUSIONS

It might thus be of particular interest to monitor children with high levels of these biomarkers, as part of a longitudinal study in order to determine if the excretion profile at a young age is predictive of the outcomes of disease severity in adulthood.

Functional and Clinical Consequences of Novel α-Galactosidase A Mutations in Fabry Disease

Fabry disease (FD) is a rare metabolic disorder of glycosphingolipid storage caused by mutations in the GLA gene encoding lysosomal hydrolase α-galactosidase A (α-gal A). Recently, the diagnostic procedure for FD has advanced in several ways, through the development of a specific biomarker (lyso-Gb3) and the implementation of newborn screenings, which acted as a catalyst to augment general awareness of the disease. Heterologous over-expression of α-gal A variants and subsequent in vitro measurement of enzyme activity provided molecular data to elucidate the relationship between mutation, enzyme damage, lyso-Gb3 biomarker levels, and clinical phenotype. This knowledge is the foundation for improved counseling with regard to prognosis and therapeutic decisions. Herein, we resume the approach of in vitro characterization, with a further 73 mainly novel GLA gene mutations. Patient lyso-Gb3 data were available for most of the mutations. All mutations were tested for responsiveness to pharmacological chaperone treatment and phenotypic data for 61 hemizygous male and 116 heterozygous female patients carrying a mutation associated with ≥ 20% residual activity, formerly classified as "mild" variant, were collected in order to evaluate the pathogenicity. We conclude that a mild GLA variant is typically characterized by high residual enzyme activity and normal biomarker levels. We found evidence that these variants can still be classified as a distinctive, but milder, sub-type of FD.

[Comparison of patients from a Spanish Registry of Fabry disease in two periods]

BACKGROUND AND OBJECTIVE

Fabry disease (FD) is a rare X-linked lysosomal storage disorder caused by a deficiency of the enzyme alpha-galactosidase A, that leads to multiorgan dysfunction and premature death. Data from the first 24 Spanish patients enrolled on the Fabry Outcome Survey (FOS) were published in 2004, with a significant increase in the number of patients since then. This manuscript analyzes whether the clinical profile or diagnosis of these patients between the 2 periods has changed.

PATIENTS AND METHODS

In 2009 the FOS included data from 92 patients. Patients included up to 2003 and those included after that year (68) were compared by sex, regarding age at onset of symptoms and diagnosis, severity and previous misdiagnoses. Similar analysis was performed between the index cases (31) and the other patients.

RESULTS

Mean delay in diagnosis was 10 years for both sexes. Male had a classic phenotype, and up to 40% of the females reported symptoms. In females, the enzyme activity seemed to determine disease severity. No differences were observed in any parameter when comparing the patients included in the first period to those included afterwards, nor when comparing index cases with the rest of the patients.

CONCLUSIONS

Registries like FOS have a great value to deepen our understanding of rare diseases. We confirm that women are not just carriers of the disease. There is still a lack of education and awareness in order to include FD in the differential diagnosis of other processes. Complete family studies would allow early diagnosis of this disorder.

Descriptive epidemiology of Fabry disease among beneficiaries of the Specified Disease Treatment Research Program in Japan

Background

Fabry disease (FD) is a rare X-linked lysosomal storage disorder and is included in the Specified Disease Treatment Research Program in Japan, which subsidizes medical care for beneficiaries with rare and other, designated diseases. However, no report on the epidemiologic features of Fabry disease has been published in Japan.

Methods

We used clinical research data reports submitted to the program between 2003 and 2008 to assess the epidemiologic features of 315 beneficiaries with FD.

Results

Of the 315 program beneficiaries, 198 were men (mean age, 37.4 years) and 117 were women (mean age, 51.2 years). The overall incidence in Japan was 0.25 cases per 100 000 individuals, and prevalence among men was 1.78 times that among women. More than 80% of beneficiaries were capable of working, going to school, or doing housework; however, 46 beneficiaries (14.6%) required home care, and 9 (2.9%) were living in hospitals or other medical facilities. As compared with the previous year, the clinical course of FD at beneficiary registration was unchanged for 178 of 290 beneficiaries (61.4%), worse for 81 (27.9%), and improved or cured for 31 (10.7%). The distribution of beneficiary-related characteristics was similar between men and women, and no significant difference was observed.

Conclusions

The high percentage (>80%) of individuals with FD who were able to work, attend school, and perform tasks such as housework could reflect an improvement in the clinical course of FD after enzyme replacement therapy. We must continue data collection and conduct further studies to improve our understanding of the descriptive epidemiology of FD.

Fabry disease in Spain: description of Spanish patients and a comparison with other European countries using data from the Fabry Outcome Survey (FOS)

AIMS

Fabry disease (FD) is an X-chromosome-linked transmitted lysosomal storage disorder as a result of the deficient activity of enzyme α-galactosidase A. This leads to accumulation of neutral glycosphingolipids associated with organ involvement and premature death. We report the clinical characteristics of Spanish patients enrolled on the Fabry Outcome Survey (FOS; an international multicentre registry for the disease) and also compare these data with those from the rest of Europe.

METHODS

Baseline clinical data of 92 patients (41 males and 51 females) are described and analysed globally and according to gender. We compare the data of Spanish patients with those previously published from the rest of Europe patients in FOS.

RESULTS

Mean age of onset of symptoms in men was 20, and 24 years in women, with a mean delay of 11 years to the diagnosis in both genders. The predominant clinical involvement in male patients was renal (69%), cardiac (66%) and neurological (60%), and for female patients, it was neurological (42%), cardiac (33%), keratopathy (30%) and nephropathy (28%). Disease severity was significantly higher in male patients. Compared to the rest of European FOS-patients, Spanish patients were diagnosed at an earlier age with a smaller proportion of disease-related involvement for most organ irrespective of gender, though not its global severity in male patients.

CONCLUSIONS

We present the largest cohort of Spanish patients diagnosed with FD. The pattern of involvement (though not its global severity) could be different in Spanish patients in comparison with others from Europe. Expanding the knowledge of FD will permit early diagnosis as well as the possibility of starting the specific treatment.