A recent comparison study between a four-color PTEN FISH assay and a two-color PTEN FISH assay using benign prostatic hyperplasia as a control tissue source for prostate cancer showed that two-color PTEN FISH has a mean of 12% of false-positive cells due to truncation losses whereas four-color PTEN FISH has a mean false-positive rate of only 4%. The gene discussed is PTEN; the disease is benign prostatic hyperplasia.