Technical considerations when designing a gene expression panel for renal transplant diagnosis

Area of Science:

• Transplant pathology and molecular diagnostics.
• Gene expression profiling for disease assessment.

Background:

• Gene expression analysis is a developing diagnostic method in transplant pathology, especially for antibody-mediated rejection.
• Diagnostic gene panels require validation for robustness across various preservation techniques and analysis platforms.

Purpose of the Study:

• To evaluate the impact of tissue sampling and preservation on candidate genes for renal transplant diagnostic panels.
• To assess the reliability of gene expression data obtained from different preservation methods.

Main Methods:

• Compared expression of 219 genes in 51 renal transplant samples using the NanoString platform.
• Samples were divided into formalin-fixed paraffin-embedded (FFPE) and RNAlater preservation groups.
• Validated NanoString results against qRT-PCR for 18 genes from RNAlater preserved samples.

Main Results:

• Overall gene expression correlated significantly between FFPE and RNAlater samples.
• However, 46 out of 219 genes (21%) showed no significant correlation between preservation methods at the individual gene level.
• NanoString and qRT-PCR showed significant correlation for 17 out of 18 genes.

Conclusions:

• A significant proportion of candidate genes show variable expression depending on tissue preservation method (FFPE vs. RNAlater).
• This variability may be attributed to fixatives or tissue sampling differences.
• Gene panel selection for routine renal transplant diagnostics must consider these preservation-related effects for accurate results.