Kidney Week

Abstract: PO1529

Cystic Kidney Disease in Patients with Thin Basement Membrane Disease (TBMD)

Session Information

• Cystic Kidney Diseases: Mechanisms, Genetics, and Treatment
  October 22, 2020 | Location: On-Demand
  Abstract Time: 10:00 AM - 12:00 PM

Category: Genetic Diseases of the Kidneys

• 1001 Genetic Diseases of the Kidneys: Cystic

Authors

• Sy-Go, Janina Paula Tiulentino, Mayo Clinic Minnesota, Rochester, Minnesota, United States

Janina Paula Tiulentino Sy-Go,

• Said, Samar M., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Samar M. Said,

• Miao, Jing, Mayo Clinic Minnesota, Rochester, Minnesota, United States

Jing Miao,

• Potretzke, Theodora A., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Theodora A. Potretzke,

• Singh, Prince, Mayo Clinic Minnesota, Rochester, Minnesota, United States

Prince Singh,

• Neal, Reem M., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Reem M. Neal,

• Harris, Peter C., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Peter C. Harris,

• Torres, Vicente E., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Vicente E. Torres,

• Nasr, Samih H., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Samih H. Nasr,

• Chebib, Fouad T., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Fouad T. Chebib,

Background

TBMD is a benign glomerular disease typically manifesting as microscopic hematuria with/without minimal proteinuria and with preserved kidney function. A few reports described the finding of kidney cysts in TBMD patients, but this association remains uncertain.

Methods

A retrospective study of patients seen at a tertiary academic center (2009-2019) and had a kidney biopsy with reported diffuse glomerular basement (GBM) thinning was done. The diagnosis of TBMD was confirmed by a careful review of the biopsy findings, including EM images. Patients with clinical and/or pathologic features of Alport disease or with unavailable abdominal imaging were excluded. Cyst number and size were recorded on the first available imaging.

Results

Among 49 TBMD patients, 29 (59%) had kidney cysts (cystic), and 20 had no cysts (noncystic). Both cystic and noncystic groups were mostly females (69% vs. 80%). Cystic patients were older at time of biopsy (51 vs. 38 yrs) and imaging (51 vs 39 yrs). Hematuria was the major indication for biopsy. Hematuria and dysmorphic RBCs were found in 72% and 41% of cystic patients respectively vs. 80% and 10% in noncystic patients. Cystic patients had lower mean eGFR at time of biopsy (69 vs. 93 mL/min/1.73 m²), higher mean 24-h proteinuria (968 vs. 172 mg/d), and comparable mean GBM thickness (193 vs. 206 nm). 18 (62%) patients had bilateral cysts. Median number of cysts was 3 (IQR 1-5.5). Average sizes of the smallest and largest cysts were 5.1 (+ 4) and 19.6 (+ 24) mm respectively. The number of cysts (≥5 mm) in 34% of cystic patients was above the 97.5th percentile of an age-/sex-matched control population (Figure 1).

Conclusion

Bilateral kidney cysts were found in a large percentage of biopsy-proven TBMD patients. COL4A mutations could be a potential etiology of mild cystic kidney disease with hematuria or mild proteinuria.

No. of cysts at imaging.