Gene expression analysis of human renal biopsies: recent developments towards molecular diagnosis of kidney disease

The analysis of renal tissue from kidney biopsies by histology, electron microscopy and immunohistology represents the current standards used to establish a specific diagnosis in nephrology. Recent progress in gene expression-based tissue analysis may provide fundamentally novel information in renal biopsy interpretation. In this review, progress towards the routine application of this approach is summarized.

Renal disease is characterized by closely interrelated mechanisms of inflammation, repair, scarring and atrophy affecting over 20 different intrinsic renal cell types. The renal biopsy sample represents a 'snapshot' of these dynamic processes. A central question for molecular diagnosis is whether specific gene expression patterns can adequately define segments of these disease processes. Can molecular markers be extracted as effectively as has been shown in oncology? Several studies have been able to correlate renal gene expression patterns with clinical parameters, renal histological findings and patient follow-up data. In small populations, molecular markers have been able to provide novel diagnostic, prognostic and differential therapeutic information beyond conventional histology.

A growing number of renal gene expression projects are generating targets for the integration of molecular approaches into kidney biopsy evaluation. If these molecular makers can pass rigorous testing for their diagnostic value, they should become an indispensable part of the management of the renal patient.