Fabry disease is a rare, X-linked, lifelong progressive lysosomal storage disorder. Severely deficient α-galactosidase A activity in males is associated with the classic phenotype with early-onset, multisystem manifestations evolving to vital organ complications during adulthood. We assessed the ability of 2 low-dose agalsidase beta regimens to lower skin, plasma, and urine globotriaosylceramide (GL-3) levels, and influence clinical manifestations in male pediatric Fabry patients. In this multicenter, open-label, parallel-group, phase 3b study, male patients aged 5-18 years were randomized to receive agalsidase beta at 0.5 mg/kg 2-weekly (n = 16) or 1.0 mg/kg 4-weekly (n = 15) for 5 years. All had plasma/urine GL-3 accumulation but no clinically evident organ involvement. The primary outcome was GL-3 accumulation in superficial skin capillary endothelium (SSCE). The mean age was 11.6 (range: 5-18) years and all but one of the 31 patients had classic GLA mutations. In the overall cohort, shifts from non-0 to 0-scores for SSCE GL-3 were significant at years 1, 3, and 5, but results were variable. Plasma GL-3 normalized and urine GL-3 reduced substantially. Higher anti-agalsidase beta antibody titers were associated with less robust SSCE GL-3 clearance and higher urine GL-3 levels. Renal function remained stable and normal. Most Fabry signs and symptoms tended to stabilize; abdominal pain was significantly reduced (-26.3%; P = .0215). No new clinical major organ complications were observed. GL-3 accumulation and cellular and vascular injury were present in baseline kidney biopsies (n = 7). Treatment effects on podocyte GL-3 content and foot process width were highly variable. Fabry arteriopathy overall increased in severity. Two patients withdrew and 2 had their agalsidase beta dose increased. Our findings increase the limited amount of available data on long-term effects of enzyme replacement therapy in pediatric, classic Fabry patients. The low-dose regimens studied here over a period of 5 years did not demonstrate a consistent benefit among the patients in terms of controlling symptomatology, urine GL-3 levels, and pathological histology. The current available evidence supports treatment of pediatric, classic male Fabry patients at the approved agalsidase beta dose of 1.0 mg/kg 2-weekly if these patients are considered for enzyme replacement therapy with agalsidase beta.

Oxidative stress and inflammation contribute significantly to atherogenesis. We and others have demonstrated that mildly elevated serum bilirubin levels protect against coronary and peripheral atherosclerosis, most likely due to the antioxidant and anti-inflammatory activities of bilirubin. The aim of the present study was to assess serum bilirubin and the markers of oxidative stress and inflammation in both healthy subjects and patients with various forms of atherosclerosis. The study was performed in patients with premature myocardial infarction (n = 129), chronic ischemic heart disease (n = 43), peripheral artery disease (PAD, n = 69), and healthy subjects (n = 225). In all subjects, standard serum biochemistry, UGT1A1 genotypes, total antioxidant status (TAS), and concentrations of various pro- and anti-inflammatory chemokines were determined. Compared to controls, all atherosclerotic groups had significantly lower serum bilirubin and TAS, while having much higher serum high-sensitivity C-reactive protein (hsCRP) and most of the analyzed proinflammatory cytokines (p < 0.05 for all comparisons). Surprisingly, the highest inflammation, and the lowest antioxidant status, together with the lowest serum bilirubin, was observed in PAD patients, and not in premature atherosclerosis. In conclusion, elevated serum bilirubin is positively correlated with TAS, and negatively related to inflammatory markers. Compared to healthy subjects, patients with atherosclerosis have a much higher degree of oxidative stress and inflammation.

Key Points: The clinical significance of a number of missense variants of α-galactosidase A is often ambiguous. Defective proteostasis of some missense α-galactosidase A variants induced chronic endoplasmic reticulum stress and the unfolded protein response. Endoplasmic reticulum stress and the unfolded protein response may explain clinical manifestations of non-classic Fabry disease. Background: Classic Fabry disease is caused by GLA mutations that result in loss of enzymatic activity of α-galactosidase A, lysosomal storage of globotriaosylceramide, and a resulting multisystemic disease. In non-classic Fabry disease, patients have some preserved α-galactosidase A activity and a milder disease course. Heterozygous female patients may also be affected. While Fabry disease pathogenesis has been mostly attributed to catalytic deficiency of mutated α-galactosidase A, lysosomal storage, and impairment of lysosomal functions, other pathogenic factors may contribute, especially in nonclassic Fabry disease. Methods: We characterized the genetic, clinical, biochemical, molecular, cellular, and organ pathology correlates of the p.L394P α-galactosidase A variant that was identified initially in six individuals with kidney failure by the Czech national screening program for Fabry disease and by further screening in an additional 24 family members. Results: Clinical findings in affected male patients revealed a milder clinical course, with approximately 15% residual α-galactosidase A activity with normal plasma lyso-globotriaosylceramide levels and abnormally low ratio of these values. None of the four available kidney biopsies showed lysosomal storage. Laboratory investigations documented intracellular retention of mutated α-galactosidase A with resulting endoplasmic reticulum stress and the unfolded protein response, which were alleviated with BRD4780, a small molecule clearing misfolded proteins from the early secretory compartment. We observed similar findings of endoplasmic reticulum stress and unfolded protein response in five kidney biopsies with several other classic and non-classic Fabry disease missense α-galactosidase A variants. Conclusions: We identified defective proteostasis of mutated α-galactosidase A resulting in chronic endoplasmic reticulum stress and unfolded protein response of α-galactosidase A expressing cells as a contributor to Fabry disease pathogenesis.

Aims: Fabry disease (FD) is often associated with heart failure (HF). However, data on HF prevalence, prognosis, and applicability of echocardiographic criteria for HF diagnosis in FD remain uncertain. Methods and results: We evaluated patients with genetically proven FD for symptoms and natriuretic peptides indicating HF. We then analysed the diagnostic utility of the currently recommended European Society of Cardiology (ESC) echocardiographic criteria for HF diagnosis and their relationship to natriuretic peptides. Finally, we examined the association between HF and echocardiographic criteria with mortality and cardiovascular events during follow-up. Of 116 patients with FD, 48 (41%) had symptomatic HF (mean age 58 ± 11 years, 62% male). HF with preserved ejection fraction (HF-pEF) was diagnosed in 43 (91%) patients, representing the dominant phenotype. Left ventricular mass index (LVMi) had the highest diagnostic utility (sensitivity 71% and specificity 83%) for HF diagnosis in FD, followed by E/e′ > 9 (sensitivity 76% and specificity 78%) and global longitudinal strain (GLS) <16% (sensitivity 54% and specificity 88%). Log N-terminal pro-brain natriuretic peptide correlated significantly with LVMi (r = 0.60), E/e′ (r = 0.54), and GLS (r = 0.52) (all Ps < 0.001) but not with left ventricular ejection fraction (r = −0.034, P = 0.72). During follow-up (mean 1208 ± 444 days), patients diagnosed with HF had a higher rate of all-cause mortality and worsening HF (33% vs. 1.5%, P < 0.001). Abnormal LVMi, E/e′ > 9, and GLS < 16% were all associated with higher all-cause mortality and worsening HF. Conclusions: This study found a high prevalence of symptomatic HF in FD patients. HF-pEF was the dominant phenotype. LVMi, E/e′, and GLS yielded the highest diagnostic utility for HF diagnosis and were significantly correlated with natriuretic peptides levels. Echocardiographic criteria proposed by current ESC HF guidelines apply to Fabry patients and predict cardiovascular events. At follow-up, Fabry patients with HF diagnosis had high event rates and significantly worse prognosis than patients without HF.