Two major immune system genes under investigation are interleukin-12 subunit beta ( IL12B ) on chromosome 5q , which expresses interleukin-12B; and IL23R on chromosome 1p, which expresses the interleukin-23 receptor, and is involved in T cell differentiation. Interleukin-23 receptor and IL12B have both been strongly linked with psoriasis.  T cells are involved in the inflammatory process that leads to psoriasis.  These genes are on the pathway that upregulate tumor necrosis factor-α and nuclear factor κB , two genes involved in inflammation.  Recently, the first gene directly linked to psoriasis has been identified. A rare mutation in the gene encoding for the CARD14 protein plus an environmental trigger was enough to cause plaque psoriasis (the most common form of psoriasis).  
This topical treatment has apparently proved very effective in reducing her symptoms, particularly decreasing itchiness, as well as improving the appearance of affected areas. It took around a week of application, nightly before bed, for her to notice significant improvement, so I would not expect results overnight. The method is simple and I’ll share it here, but obviously one person is not much of a sample size. I’d be interested to hear anyone else’s results, but once again stress the importance of patch testing a small area the day before applying fully to check for any negative reactions.
Psoriasis is a medical condition in which skin cells die and build up rapidly. Psoriasis creates blotchy, flaky patches on your skin that may itch or feel painful. It can occur anywhere on the body, including on the face. If you have psoriasis on your face, you will want to treat it carefully, as the skin on your face is very sensitive. Depending on how severe your psoriasis is, you may wish to use topical treatments, phototherapy (or light therapy), systemic medications, or a combination of several treatments. There is also some evidence that lifestyle changes can reduce psoriasis symptoms.