Two genes clear up psoriasis and eczema confusion

A test might prevent hundreds of thousands of misdiagnosed cases of skin disease by simply checking two genes, scientists report in the July 9 Science Translational Medicine.

Eczema and psoriasis are widespread, affecting 10 percent and 3 percent of the population, respectively. Both skin diseases produce itchy red patches that can look similar, even under the microscope. Accurate diagnosis is crucial because treatmentsfor one disease can exacerbate symptoms of the other, says dermatologist Kilian Eyerich of the Munich University of Technology in Germany. And some of the drugs cost $10,000 to $15,000 a year, he adds.

Disease-specific genes could distinguish between the two, but so far scientists have searched in vain for such markers. The genes involved in each condition can differ between patients, so Eyerich and his colleagues compared tissue samples for eczema and psoriasis collected from 24 people afflicted with both disorders. After sequencing RNA from patients’ tissue samples, the team discovered 15 genes that could distinguish psoriasis from eczema.

The researchers screened the two best classifier genes, NOS2 and CCL27, among a second group of 34 patients, 16 with psoriasis and 18 with eczema. The researchers found that the two-gene test could discriminate between the disorders in every case.