New approaches for genotyping paraffin wax embedded breast tissue from patients with cancer: the Iowa women's health study

Abstract

Background: The use of paraffin wax embedded tissue samples as a source of DNA for genotype analysis has been limited because of difficulties in DNA extraction and single nucleotide polymorphism (SNP) analysis.

Aims: To test the feasibility of applying the combination of a commonly used DNA isolation procedure, PureGene, and a high throughput SNP analysis method, the polymerase chain reaction (PCR)-INVADER assay, to genotype several types of paraffin wax embedded breast tissues.

Methods: Twenty formalin fixed, paraffin wax blocks were obtained from five participants in the Iowa women's health study. Each participant provided several types of tissue including normal lymph node, normal nipple/areola tissue, inflammatory/fibrotic breast tissue, or normal breast tissue, and tumour tissue.

Results: Good quality DNA (260/280 ratio >1.6) was obtained from all tissues. Normal lymph nodes yielded the largest amount of DNA (97.1 mug). DNA obtained from the samples was tested for a germline C1183T polymorphism in the MnSOD gene by three methods-PCR-RFLP (restriction fragment length polymorphism), INVADER assay, and PCR-INVADER assay. Of the 20 samples, PCR-RFLP genotyped 16, the PCR-INVADER assay 18, and the INVADER assay two. This methodology was then used to analyse five additional genotypes and confirmed the general applicability of the method.

Conclusions: This study demonstrated the feasibility of (1) using several paraffin wax embedded breast tissues as a source of DNA for germline genetic analysis, with lymph nodes providing the highest yield, and (2) using the combination of a common extraction method with a high throughput SNP analysis method, the PCR-INVADER assay.

Figure 1

Schematic representation of the monoplexed INVADER® assay. The Cleavase® enzyme recognises the invasive structure formed by the probe and INVADER oligonucleotides in the presence of the appropriate target. ©Third Wave Technologies, Inc 2003; figure and legend reproduced with permission from Third Wave Technologies Inc. Mut, mutant; WT, wild-type.