Natural History and Structural Functional Relationships in Fabry Renal Disease Natural History, Structural Functional Relationships and Determinants of Renal Structural Responses (Changes) With Enzyme Replacement Therapy in Fabry Disease
University of Minnesota
Summary
The investigators will perform a study with two major components. The first is a natural history study of untreated Fabry patients. This study component will detail kidney microscopic structural changes in Fabry patients before starting enzyme replacement therapy and will correlate these changes with kidney function, including glomerular filtration rate and urinary albumin excretion rate. The investigators will perform studies on samples obtained at baseline, or before enzyme replacement therapy is initiated. The goal of our study is to find kidney microscopic changes in the biopsies that are associated with kidney disfunction. Our hypotheses for this study are: 1. Much of the natural history of Fabry renal structural changes will occur without detectable renal functional alterations. 2. Structural changes associated with the initial onset of proteinuria and those associated with the subsequent progressive loss of filtration function will differ and will be best described by non-linear models. 3. There will be sufficient precision of Fabry renal structural-functional relationships to support renal structure as an acceptable clinical trial surrogate endpoint for later renal functional deterioration. The second component examines the effects of age and gender at start of enzyme replacement therapy (ERT), as well as dosage levels of ERT on the renal cellular clearance of GL3 from Fabry patients by comparing baseline to follow-up kidney biopsies performed 5, 11, and 60 months later, with all comparisons matched for ERT treatment duration. Our hypotheses for this component of the study are as follows: 1. Enzyme Replacement Therapy(ERT) instituted at younger ages is more effective in reducing podocytes(PC),distal tubular cells(DTC),and arterial smooth muscle cells (ASMC)GL-3 than in older Fabry patients. 2. Earlier institution of ERT will stabilize PC numbers while later ERT institution, especially in proteinuric adults, may not prevent progressive decline in PC numbers and associated glomerular sclerosis, tubulointerstitial injury, and GFR loss. 3. Whereas lower ERT dose may effectively clear GL-3 from endothelial and mesangial cells, it will be less effective in clearing GL-3 from PC and also from DTC and ASMC. 4. Affected cells will be cleared of GL-3 equivalently in females and males.
Description
Fabry disease is a rare genetic disease with deficient activity of enzyme alpha-galactosidase A. Deficient activity of this enzyme leads to the accumulation of lipid-derived inclusions in different organs including kidney, heart and vessels. These inclusions can be found in the kidney even before birth. The earliest known clinical manifestation of Fabry kidney disease is the appearance of excess protein in the urine, which usually occurs in the second decade of life. However, our studies, as well as those of other investigators show evidence that kidney injury starts much earlier. Once excess…
Eligibility
- Age range
- 1–75 years
- Sex
- All
- Healthy volunteers
- No
Inclusion Criteria: * Patients diagnosed with Fabry disease who have/have not received enzyme replacement therapy where a clinical decision has been made to obtain a kidney biopsy, a GFR, and urinary albumin studies or where patients have previously completed clinical trials which included measures of renal function and renal biopsies. Exclusion Criteria: * Patients with serum creatinine more than 2.5 mg/dL or known to have a renal disease other than Fabry.
Locations (2)
- University of MinnesotaMinneapolis, Minnesota
- Universtity of Minnesota, Department of Pediatric NephrologyMinneapolis, Minnesota