We have described the development and validation of a new gene-expression diagnostic test called Pheo-type for classification of PPGL tumors based on the underlying genetic driver of the disease. Our assay confirms that the predominant gene-expression subtypes of PPGL are closely linked to tumor genotype and for the first time show that classification can be achieved using a relatively small gene set. Pheo-type is similar to other clinical assays developed on the Nanostring platform for subtyping of solid tumors (50–52). As with these other studies, we have shown that robust gene-expression analysis can be achieved from small amounts of FFPE tissue material generating data that are comparable to other gene-expression platforms. The assay is rapid, largely automated, and cost effective, enabling the generation of results in 2 days from RNA extraction to data analysis, facilitating its implementation in a routine diagnostic laboratory.

The patient's age suggested familial disease, and testing for genes associated with phaeochromocytoma was conducted. Germ line mutation analysis of the three exons of the VHL gene was performed by polymerase chain reaction and sequencing. A missense mutation c.308C>A (p.Pro103His), not previously reported, was detected in exon 1 (Fig. 3). Figure 3Open in figure viewerPowerPoint Electropherograms showing germ line von Hippel Lindau (VHL) sequence for normal control (a) and patient (b) as described with VHL exon 1 mutation, c.308C>A. At codon 103, the sequencing trace for the normal control (a) reads CCT (proline) but in the patient (b), the mutant allele reads CAT (histidine).