Diet and Physical Activity in Fabry Disease: A Narrative Review.

Fabry disease (FD) is caused by mutations in the galactosidase alpha (GLA) gene which lead to the accumulation of globotriaosylceramide (Gb-3). Enzyme replacement therapy (ERT) and oral chaperone therapy are the current pharmacological treatments for this condition. However, in the literature, there is a growing emphasis on exploring non-pharmacological therapeutic strategies to improve the quality of life of patients with FD. In particular, the nutritional approach to FD has been marginally addressed in the scientific literature, although specific dietary interventions may be useful for the management of nephropathy and gastrointestinal complications, which are often present in patients with FD. Especially in cases of confirmed diagnosis of irritable bowel syndrome (IBS), a low-FODMAP diet can represent an effective approach to improving intestinal manifestations. Furthermore, it is known that some food components, such as polyphenols, may be able to modulate some pathogenetic mechanisms underlying the disease, such as inflammation and oxidative stress. Therefore, the use of healthy dietary patterns should be encouraged in this patient group. Sports practice can be useful for patients with multi-organ involvement, particularly in cardiovascular, renal, and neurological aspects. Therefore, the aim of this review is to summarize current knowledge on the role of nutrition and physical activity in FD patients.

Real-world management of chronic and postprandial hyperkalemia in CKD patients treated with patiromer: a single-center retrospective study.

INTRODUCTION: Hyperkalemia, one of the most important electrolyte abnormalities of chronic kidney disease (CKD), often limits the use of renin-angiotensin-aldosterone system inhibitors and can increase in the postprandial period. In this study we report a real-world experience with the new non-adsorbed potassium binder patiromer in stage 3b-4 CKD patients. Moreover, we performed a cross-sectional analysis to evaluate, for the first time, the efficacy of patiromer in the control of postprandial potassium concentrations. METHODS: We retrospectively collected data of 40 patients at the time of patiromer initiation (T0), and after 2 (T2), 6 (T6) and 12 (T12) months of treatment. For cross sectional analysis, a blood sample was collected 2 h after the main meal for the evaluation of postprandial potassium concentrations. RESULTS: Eighty-two point five percent of patients (33/40) reached normal potassium concentrations at T2. Serum potassium significantly decreased at T2 compared to T0 (5.13 ± 0.48 vs 5.77 ± 0.41 mmol/L, respectively; p < 0.001) and the reduction remained significant during the follow-up (5.06 ± 0.36 at T6 and 5.77 ± 0.41 at T12; p < 0.001 vs T0). Renin-angiotensin-aldosterone system inhibitors were continued by 93% of patients (27/29). Adverse events were reported in 27.5% of patients and were all mild-to-moderate. Postprandial potassium concentrations did not significantly change compared to fasting state potassium measured at T12 (4.53 ± 0.33 vs 5.06 ± 0.36 mmol/L; p = 0.15). CONCLUSIONS: In a real-world setting of advanced CKD patients, patiromer is a useful treatment for hyperkalemia, since it significantly reduces serum potassium levels over the long term and is able to maintain potassium concentrations in the normal range even in the post-prandial period.

[Type I Hyperprolinemia - What about the Kidney?]

Hyperprolinemia is a rare genetic condition due to mutations in proline metabolic pathway. Type I Hyperprolinemia (HPI) typically causes neuropsychiatric disorders, and diagnosis is usually confirmed in pediatric population with suggestive neuropsychiatric involvement by elevated serum proline levels and elevated urinary proline, hydroxyproline, and glycine levels. The possible coexistence of nephropathy in patients with HPI, often specified as malformative urinary disease, is often mentioned. However, reports of HPI diagnosis due to kidney impairment do not exist in scientific literature yet. Here we present the case of a patient presenting with chronic kidney disease secondary to obstructive nephropathy who received a HPI diagnosis in adulthood. Interestingly, the family study showed the same 22q11.21 deletion and elevated blood proline levels in the father, who had no clinical anomalies. We therefore suggest, in light of the high frequency of mutations involving 22q11 and PRODH in the general population, to consider these rare alterations in patients with congenital urinary malformations, even in the presence of nuanced neurological symptoms and negative family history.

Familial polycystic kidneys with no genetic confirmation: Are we sure it is ADPKD?

Autosomal dominant polycystic kidney disease (ADPKD) is the most common heritable multifocal cystic disease encountered in clinical practice, and it is usually diagnosed in patients with family history by the evidence of markedly enlarged kidneys with multiple bilateral cysts at ultrasound (U.S.), computed tomography (CT) scan, or magnetic resonance imaging (MRI). In most cases, genetic testing is not required. Though ADPKD diagnosis is often straightforward, misdiagnosis is possible. Here we present a case of ADPKD misdiagnosis, followed by a review of the most important kidney heritable multifocal cystic diseases. Our case report demonstrates that ADPKD can be erroneously diagnosed when other kidney heritable multifocal cystic diseases occur without their distinguishing manifestations and when there is no genetic characterization among the relatives. A proper diagnosis of heritable diseases is crucial, as it allows an appropriate management of family members who carry disease allele, apart from patient management. Therefore, we suggest a careful differential diagnosis with possible molecular genetic analysis in presentations with familial cystic kidneys and suspicious clinical and radiological features.

Randomized Controlled Trials on Renin Angiotensin Aldosterone System Inhibitors in Chronic Kidney Disease Stages 3-5: Are They Robust? A Fragility Index Analysis.

Inhibition of the renin-angiotensin-aldosterone system (RAAS) is broadly recommended in many nephrological guidelines to prevent chronic kidney disease (CKD) progression. This work aimed to analyze the robustness of randomized controlled trials (RCTs) investigating the renal and cardiovascular outcomes in CKD stages 3-5 patients treated with RAAS inhibitors (RAASi). We searched for RCTs in MEDLINE (PubMed), EMBASE databases, and the Cochrane register. Fragility indexes (FIs) for every primary and secondary outcome were calculated according to Walsh et al., who first described this novel metric, suggesting 8 as the cut-off to consider a study robust. Spearman coefficient was calculated to correlate FI to p value and sample size of statistically significant primary and secondary outcomes. Twenty-two studies met the inclusion criteria, including 80,455 patients. Sample size considerably varied among the studies (median: 1693.5, range: 73-17,276). The median follow-up was 38 months (range 24-58). The overall median of both primary and secondary outcomes was 0 (range 0-117 and range 0-55, respectively). The median of FI for primary and secondary outcomes with a p value lower than 0.05 was 6 (range: 1-117) and 7.5 (range: 1-55), respectively. The medians of the FI for primary outcomes with a p value lower than 0.05 in CKD and no CKD patients were 5.5 (range 1-117) and 22 (range 1-80), respectively. Only a few RCTs have been shown to be robust. Our analysis underlined the need for further research with appropriate sample sizes and study design to explore the real potentialities of RAASi in the progression of CKD.

Parapelvic Cysts: An Imaging Marker of Kidney Disease Potentially Leading to the Diagnosis of Treatable Rare Genetic Disorders? A Narrative Review of the Literature.

Simple renal cysts are a common finding during abdominal imaging assessment. The incidence increases with age and it is higher in male gender. Parapelvic cysts are a subset of simple cysts that arise within the renal parenchyma, adjacent to the renal sinus, characterized by being generally single, larger, and incompletely surrounded by renal parenchyma. Noteworthy, parapelvic cysts are a rare and understudied condition which, although considered clinically insignificant due to the absence of influence on renal function, still have a controversial aetiopathogenesis. On the other hand, urological management and differential diagnosis have been thoroughly investigated. The aim of our review is to provide an overall vision on this rare condition, usually misdiagnosed and underestimated, on the basis of more recent data. An accurate differential diagnosis of parapelvic cysts can lead to the identification of treatable conditions such as Fabry disease, autosomal dominant polycystic kidney disease, polycystic liver disease and tuberous sclerosis complex disease.

[A possible relationship between anti-SARS-CoV-2 vaccination and glomerular diseases: food for thought for the nephrologist].

In order to fight the SARS-CoV-2 pandemic, mass-vaccination programs have been launched globally starting December 2020. The pace of COVID-19 vaccines development was impressive and although data from clinical trials and post-authorization studies showed acceptable safety profile, additional studies and long-term population-level surveillance are needed. A possible link between all type of vaccination and immunological diseases is perhaps one of the hottest topics in literature; correspondingly, there is growing concern over the small but growing number of case reports linking COVID-19 vaccines with the development of glomerular disease. Our group conducted a systematic review of such cases. Results showed that IgA nephropathy (IgAN) and Minimal Change Disease (MCD) are the most frequently associated glomerulopathies. Interestingly, IgAN cases are mostly flares occurring few hours after the second dose of RNA vaccines and have a good clinical outcome, while both de novo and recurring MCD can occur up to 28 days after the first or second dose of vaccines. RNA vaccines are the most common vaccine type to be associated with glomerulopathy. Of course, this may simply reflect the more widespread use of these vaccines. However, compared to traditional vaccines, they do seem produce a higher antibody response and a stronger CD8+ T- and CD4+ T-cell response, including higher production of chemokines and cytokines.

RAAS Inhibitor Prescription and Hyperkalemia Event in Patients With Chronic Kidney Disease: A Single-Center Retrospective Study.

Hyperkalemia is common in patients treated with renin-angiotensin-aldosterone system inhibitors (RAASis), and it represents the main cause of the large gap reported between guideline recommendations and real-world practice in chronic kidney disease (CKD). We conducted a CKD-population-based restrospective study to determine the prevalence of patients with CKD treated with RAASis, incidence of hyperkalemia in patients with CKD treated with RAASis, and proportion of patients with RAASi medication change after experiencing incident hyperkalemia. Among 809 patients with CKD analyzed, 556 (68.7%) were treated with RAASis, and RAASi prescription was greater in stages 2-4 of CKD. Hyperkalemia occurred in 9.2% of RAASi-treated patients, and the adjusted rate of hyperkalemia among patients with stage 4-5 CKD was 3-fold higher compared with patients with eGFR > 60 ml/min/1.73 m2. RAASi treatment was discontinued in 55.3% of the patients after hyperkalemia event (74.2% discontinued therapy, 3.2% received a reduced dose, and 22.6% reduced the number of RAASi drugs). This study shows that the incidence of hyperkalemia is frequently observed in patients with CKD patients with RAASis, and that rates increase with deteriorating levels of kidney function from stages 1 to 3. RAASi medication change following an episode of hyperkalemia occurred in almost half of the patients after experiencing hyperkalemia.

Therapeutic advances in ADPKD: the future awaits.

Autosomal dominant polycystic kidney disease (ADPKD) is a heterogeneous genetic disorder included in ciliopathies, representing the fourth cause of end stage renal disease (ESRD), with an estimated prevalence between 1:1000 and 1:2500. It is mainly caused by mutations in the PKD1 and PKD2 genes encoding for polycystin 1 (PC1) and polycystin 2 (PC2), which regulate differentiation, proliferation, survival, apoptosis, and autophagy. The advances in the knowledge of multiple molecular pathways involved in the pathophysiology of ADPKD led to the development of several treatments which are currently under investigation. Recently, the widespread approval of tolvaptan and, in Italy, of long-acting release octreotide (octreotide-LAR), represents but the beginning of the new therapeutic management of ADPKD patients. Encouraging results are expected from ongoing randomized controlled trials (RCTs), which are investigating not only drugs acting on the calcium/cyclic adenosin monoposphate (cAMP) pathway, the most studied target so far, but also molecules targeting specific pathophysiological pathways (e.g. epidermal growth factor (EGF) receptor, AMP-activated protein kinase (AMPK) and KEAP1-Nrf2) and sphingolipids. Moreover, studies on animal models and cultured cells have also provided further promising therapeutic strategies based on the role of intracellular calcium, cell cycle regulation, MAPK pathway, epigenetic DNA, interstitial inflammation, and cell therapy. Thus, in a near future, tailored therapy could be the key to changing the natural history of ADPKD thanks to the vigorous efforts that are being made to implement clinical and preclinical studies in this field. Our review aimed to summarize the spectrum of drugs that are available in the clinical practice and the most promising molecules undergoing clinical, animal, and cultured cell studies.

Tolvaptan vs. somatostatin in the treatment of ADPKD: A review of the literature.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic disorder with an estimated prevalence between 1 : 1,000 and 1 : 2,500. Until a few decades ago, ADPKD was considered an untreatable disease, relentlessly progressing towards end-stage renal disease because of the lack of specific interventions. In the last decade, some aberrant molecular pathways involved in ADPKD development have been identified, and controlled clinical trials have been conducted to investigate the potential role of active drugs on these pathophysiological mechanisms such somatostatin and tolvaptan. Somatostatin analogues have been shown to be effective not only in ADPKD, but also in polycystic liver disease (PLD) with beneficial effect on cardiac function and a better cost/benefit profile; the only somatostatin analogue currently available for clinical use is octreotide long-acting release (octreotide-LAR), and it is approved only in Italy. On the contrary, tolvaptan is authorized worldwide and has received more attention in the last years, even if its clinical use is widely limited by aquaresis tolerability. The aim of this review is to investigate the advantages and drawbacks of somatostatin analogues and tolvaptan in the treatment of ADPKD.

The effects of somatostatin analogues on liver volume and quality of life in polycystic liver disease: a meta-analysis of randomized controlled trials.

A clear evidence on the benefits of somatostatin analogues (SA) on liver outcome in patients affected by polycystic liver disease is still lacking. We performed a meta-analysis of RCTs and a trial sequential analysis (TSA) evaluating the effects of SA in adult patients with polycystic liver disease on change in liver volume. As secondary outcome, we evaluated the effects on quality of life as measured by SF36-questionnaire. Six RCTs were selected with an overall sample size of 332 adult patients with polycystic liver disease (mean age: 46 years). Mean liver volume at baseline was 3289 ml in SA group and 3089 ml in placebo group. Overall, unstandardized mean difference in liver volume was - 176 ml (95%CI, - 406, 54; p < 0.133). Heterogeneity was low (I2:0%, p < 0.992). However, we performed a moderator analysis and we found that a higher eGFR significantly correlates to a more pronounced effect of SA on liver volume reduction (p = 0.036). Cumulative Z-curve in TSA did not reach either significance and futility boundaries or required information size. Three RCTs have evaluated Quality of life parameters measured by SF36-QOL questionnaire for a total of 124 patients; no significant difference was found on the effect of SA on QOL parameters when compared with placebo. The present meta-analysis revealed a potential effect of SA on reduction of liver volume and quality of life parameters, but results did not reach a statistical significance. These data could be explained by the need of further studies, as demonstrated through TSA, to reach an adequate sample size to confirm the beneficial outcomes of SAs treatment.

Stepwise shortening of agalsidase beta infusion duration in Fabry disease: Clinical experience with infusion rate escalation protocol.

BACKGROUND: Although enzyme replacement therapy with agalsidase beta resulted in a variety of clinical benefits, life-long biweekly intravenous infusion may impact on patients' quality of life. Moreover, regular infusions are time-consuming: although a stepwise shortening of infusion duration is allowed up to a minimum of 1.5 hr, in most centers it remains ≥3 hr, and no data exists about the safety and tolerability of agalsidase beta administration at maximum tolerated infusion rate. METHODS: In this study, we reported our experience with a stepwise infusion rate escalation protocol developed in our center in a cohort of 53 Fabry patients (both already receiving and treatment-naΪve), and explored factors predictive for the infusion rate increase tolerability. RESULTS: Fifty-two patients (98%) reduced infusion duration ≤3 hr; of these, 38 (72%) even reached a duration ≤2 hr. We found a significant difference between the mean duration reached by already treated and naΪve patients (p < .01). More severely affected patients (male patients and those with lower enzyme activity) received longer infusions for higher risk of infusion-associated reactions (IARs). A significant correlation between anti-agalsidase antibodies and IARs was found. CONCLUSION: Our infusion rate escalation protocol is safe and could improve patient compliance, satisfaction and quality of life.

Switch from enzyme replacement therapy to oral chaperone migalastat for treating fabry disease: real-life data.

The treatment options for Fabry disease (FD) are enzyme replacement therapy (ERT) with agalsidase alfa or beta, and the oral pharmacological chaperone migalastat. Since few data are available on the effects of switching from ERT to migalastat, we performed a single-center observational study on seven male Fabry patients (18-66 years) to assess the effects of the switch on renal, cardiac, and neurologic function, health status, pain, lyso-Gb3, α-Gal A activity and adverse effects. Data were retrospectively collected at time of diagnosis of FD (baseline, T0), and after 12 months of ERT (T1), and prospectively after 1 year of therapy with migalastat (T2). No patient died or reported renal, cardiac, or cerebrovascular events during the study period. The predefined measures for cardiac, renal and neurologic function, and FD-related symptoms and questionnaires were stable between baseline and the switch, and remained unchanged with migalastat. However, a significant improvement was observed in left ventricular mass index from baseline to T2 (p = 0.016), with a significative difference between the treatments (p = 0.028), and in median proteinuria from T2 vs T1 (p = 0.048). Moreover, scores of the BPI improved from baseline to T1, and remained stable with migalastat. Plasma lyso-Gb3 levels significantly decreased from baseline to T1 (P = 0.007) and T2 (P = 0.003), while did not significantly differ between the two treatments. α-Gal A activity increased from T0 to T2 (p < 0.0001). The frequency of adverse effects under migalastat and ERT was comparable (28% for both drugs). In conclusion, switching from ERT to migalastat is valid, safe and well tolerated.

Oral Sucrosomial® iron versus intravenous iron for recovering iron deficiency anaemia in ND-CKD patients: a cost- minimization analysis.

BACKGROUND: Oral iron is recommended as first line treatment of anemia in non-dialysis chronic kidney disease (ND-CKD) patients. Sucrosomial® iron, a new generation oral iron with high absorption and bioavailability and a low incidence of side effects, has shown to be not inferior to intravenous (IV) iron in the replacement of iron deficiency anemia in patients with ND-CKD. Besides the clinical benefit, it is also important to determine the comparative total costs of oral versus IV iron administrations. The aim of this study was to perform a cost-minimization analysis of oral Sucrosomial iron, compared with IV iron gluconate from an Italian societal perspective. METHODS: Cost analysis was performed on the 99 patients with ND-CKD and iron-deficiency anemia of the randomized trial by Pisani et al. Human and material resources utilization was recorded during each iron administration. According to study perspective, direct and indirect costs were considered. Costs for each resource unit were taken from official Italian sources. Probabilistic sensitivity analyses were carried out to test the robustness of the results. RESULTS: The base case analysis showed an average cost/cycle per patient of € 111 for oral iron and € 1302 for IV iron. Thus, the potential saving was equal to € 1191 per patient/cycle. The sensitivity analysis showed that the most sensitive driver is the time loss by patient and caregivers for the therapy and related-care, followed by the minutes of nursing care and the number of kilometres travelled to reach the referral centre. DISCUSSION: This study showed that oral Sucrosomial® iron could offer specific advantages in terms of potential savings, and allowed identifying some implications for future research. Such advantages still persist with the new single dose IV iron formulation available in the market, although to a lesser extent.

Identifying Fabry patients in dialysis population: prevalence of GLA mutations by renal clinic screening, 1995-2019.

BACKGROUND: Fabry disease (FD) is a rare X-linked genetic disorder of glycosphingolipid catabolism caused by mutations in the GLA gene. Its heterogeneous presentation, the paucity of specific early markers, and the absence of a genotype-phenotype correlation are associated with a delayed or missed diagnosis. The true prevalence of FD remains so far unknown. METHODS: A systematic search of FD screening studies in dialysis patients published from January 1995 until January 2019 was performed to reanalyze the prevalence of GLA mutations in this population after assigning their correct phenotype. RESULTS: Twenty five screening studies involving 39,621 dialysis patients were included. Of them, 116 [91 males (0.23%) and 25 females (0.06%)] were positive to the GLA sequencing analysis. 56 (48.2%) had benign variant, 52 (44.8%) a pathogenic GLA mutation (39 classic and 13 late onset mutations) and 8 (6.9%) a mutation of uncertain significance. The overall prevalence of GLA variants was 0.24% [CI 95%, 0.17-0.32] while the overall prevalence recalculated on basis of only pathogenetic mutations was 0.14% [CI 95%, 0.08-0.20]. This difference was significant (P = 0.048). CONCLUSIONS: Although the real prevalence of classic FD is low, the screening in the high-risk renal population remains of primary interest as an early diagnosis is fundamental for a timely specific therapy; moreover, the identification of index cases could allow patients' relatives to be investigated and promptly treated.

Early Biomarkers of Fabry Nephropathy: A Review of the Literature.

Progressive nephropathy is one of the main features of Fabry disease. Although some clinical signs of Fabry nephropathy are already present in childhood, patients are often diagnosed relatively late in the course of the disease due to the absence of specific clinical markers, while a timely diagnosis and the prompt start of enzyme replacement therapy may be beneficial in stabilizing renal function or slowing its decline. Proteinuria/albuminuria has been accepted as the most important marker for Fabry nephropathy; however, a large proportion of renal impairment occurs in nonalbuminuric state. Therefore, early biomarkers may be useful for early identification of kidney involvement. The aim of this article is to review the current available literature on all biomarkers of Fabry nephropathy, with a comprehensive and critical description of their utilization in early recognition of renal damage.

Eradication of HCV in Renal Transplant Recipients and Its Effects on Quality of Life.

BACKGROUND: The use of direct antiviral agents (DAA) has radically modified the course of HCV hepatitis in renal patients. Aim of this study was to assess the effects of HCV eradication on quality of life (QOL) in renal transplant recipients (RTR), measured by CLDQ and SF-36. METHODS: Sixteen RTR with well preserved GFR (mean: 60.3±19.3 ml/min) and chronic HCV infection with moderate liver stiffness (9.3±1.7 kPa) were given a sofosbuvir-based regimen for 12 weeks and had a 1 year follow-up. RESULTS: At end of treatment (EOT) a complete viral clearance was observed in all the patients, with normalization of most laboratory data and a consistent reduction in liver stiffness. All these parameters remained stable after 1 year, as well as renal function and proteinuria. Questionnaire data showed consistent amelioration in different "emotional" domains at EOT, which persisted after 1 year and were associated with a globally improved QOL, although there was no change in most of the "physical" domains in both questionnaires. One patient under ribavirin developed an acute anemia and withdrew from the study, but no further adverse episode was observed throughout the study. CONCLUSIONS: Our data, while confirming the efficacy of oral DAA, show that HCV infection represents a heavy psychological burden in renal transplant recipients, greatly alleviated by viral eradication, which determines a significant improvement in QOL that represents an important outcome in management of all transplant recipients. This trial is registered with ISRCTN97560076.