H. Perry Fell has stepped down as chief executive of NanoString Technologies, a computational biology startup backed with $17 million from OVP Venture Partners and Draper Fisher Jurveston.

Fell, the former chairman of Seattle Genetics, served as CEO of the company for the past five years. He's been replaced on an interim basis by Chief Financial Officer Wayne Burns, who previously served as CFO and COO of Action Engine, according to the company's Web site. OVP confirmed the departure, but did not offer an explanation. Fell remains on the board. Calls to NanoString executives were not returned.

NanoString was founded by Amber Ratcliffe, Krassen Dimitrov and Dwayne Dunaway, who won the University of Washington Business Plan Competition in 2003. The technology was originally developed in the lab of Leroy Hood, co-founder of the Institute for Systems Biology.

NanoString's technology uses "molecular barcodes" to help researchers validate "gene expression signatures." The Genome Sequencing Center at Washington University School of Medicine in St. Louis signed an agreemnt to use the system earlier this year in a large-scale diabetes study.