A nationwide cross-sectional analysis of biopsy-proven Fabry nephropathy: the Japan Renal Biopsy Registry

Background Fabry disease (FD) is an X-linked inherited disease where renal complications are associated with a poor prognosis. However, little is known about the prevalence of Fabry nephropathy (FN) in patients with chronic kidney disease (CKD). We extracted FN data from the Japan Renal Biopsy Registry, analyzed the prevalence of FN, and examined the correlation between clinical characteristics and renal involvement according to sex differences and hemi- and heterozygosity in patients with FD. Methods A total of 38,351 participants who underwent renal biopsy were retrospectively enrolled, and FN was determined. The clinical characteristics of FD patients were examined based on sex differences. Results Twenty-nine patients (0.076%) (19 males and 10 females, mean age: 43.7 +/- 15.5 years old) were diagnosed with FN. Median estimated urinary protein (UP) and mean eGFR levels were 0.9 [interquartile range (IQR) [0.7-1.6] g/gCr and 67.1 +/- 36.8 mL/min/1.73 m(2), respectively. Mean systolic blood pressure (SBP) was 126.4 +/- 17.1 mmHg and diastolic blood pressure was 76.1 +/- 12.6 mmHg. An inverse correlation between eGFR and logarithm UP levels was observed (r(2) = 0.23, p = 0.02), SBP was positively associated with logarithm UP (r(2) = 0.34, p = 0.004) overall and inversely associated with eGFR (r(2) = 0.25, p = 0.007) regardless of sex, and SBP was an independent determinant of proteinuria (p = 0.004) and eGFR (p = 0.007). Conclusions The prevalence of biopsy-proven FN was 0.076%. Since SBP is associated with eGFR regardless of zygosity, strict SBP control might be necessary to prevent progression to end-stage kidney disease in both male and female patients with FN.