Psoriasis Causes

CAUSES : The cause of the disease is still unknown. Viral, immune and metabolic theories are widely discussed, however in recent studies the scientific attention is focused on

Genetic predisposition
Approximately 40% of patients with psoriasis or psoriatic arthritis have first-degree relatives who are affected. The sibling occurrence risk is approximately 8%. Although concordance rates of psoriatic arthritis in twins are not yet known, a 65-72% concordance rate of psoriasis exists between monozygotic twins, compared with a 15-30% concordance for dizygotic twins. A 65-72% concordance exists between monozygotic twins compared with a 15-30% concordance for dizygotic twins.

The following important genetic susceptibility loci have been elucidated :

Early-onset psoriasis: HLA-Cw6, HLA-B57, HLA-DR7, and HLA-B17 with HLA Cw*0602 variant found to be highly associated

Psoriasis: HLA-Cw6 (or psoriasis susceptibility 1 [PSOR1] on chromosome 6) and 6 other psoriasis susceptibility loci (PSOR2, PSOR3, PSOR4, PSOR5, PSOR6, PSOR7), transcription factor RUNX1

Psoriatic arthritis: HLA-B7, HLA-B27, HLA-DR4, HLA-38, HLA-DR7

Psoriasis and psoriatic arthritis: HLA-Cw6, HLA-B13, HLA-B17, HLA-B57, and HLA-B39

Predictors for gene progression: HLA-B39; HLA-B27 in the presence of HLA-DR7; HLA-DQ3 in the absence of HLA-DR7

Protective: HLA-B22

The following associated gene polymorphisms are also thought to be associated with psoriasis and psoriatic arthritis:

TNF-alpha promoter

MHC class I-chained related gene A (MICA)

Caspase-activating recruitment domain (CARD) 15

Interleukin (IL)–12/IL-23p40 and IL-23 receptor

Triggering factors

(mechanical, thermal, electromagnetic, and changes in season and climate etc), Winter tends to be the most challenging season for persons suffering from psoriasis. It has been observed that cold weather is a common trigger for many people whereas on other hand a hot and sunny climate tends to clear the skin. Sunburn on the other hand, can act as a triggering factor for psoriasis.

Skin Injury

People with psoriasis often notice new lesions 10 to 14 days after the skin is cut, s c r a t ched, rubbed, or severly sunburned. This is called “Koebner's phenomenon” ( The so-called Koebner phenomenon in psoriasis may be initiated by the release of proinflammatory neuropeptides in the traumatized human skin_[8] ) . All types of trauma have been associated with the development of psoriasis especially plaque psoriasis, Even excessive scratching can aggravate or precipitate localized psoriasis.

Infectious

Candida albicans (thrush), Human immunodeficiency virus (HIV) , Staphylococcal skin infections (boils) S t r e p t o c o c c a l p h a r y n g i t i s (streptococcal throat) , Viral upper respiratory tract infection

[ Advices for living with HIV ] Medicamentous

Anti-malarial drugs - It has been observed that psoriasis may develop after taking an anti-malarial medication in some persons

Beta-blockers (medication used to treat high blood pressure) and heart medication - These worsen psoriasis in some people.

Non-steroidal medications - used to treat arthritis and other inflammatory conditions may worsen psoriasis in some people.

Lithium used to treat manic depression and other psychiatric conditions aggravates psoriasis in many persons. And also drugs like -  (tetracyclines, ACE inhibitors,corticostertoids.)

Emotional stress and Hormonal disturbance

especially in association with hormonal disturbance, is an endogenous triggering factor. Some of the research studies have shown that the severity of psoriasis may fluctuate with hormonal changes. Disease frequency peaks during puberty and menopause. When hormone levels increase during pregnancy, symptoms are more likely to improve than worsen. In contrast, symptoms are more likely to flare in the postpartum period, if any changes occur at all

 Smoking: An increased risk of chronic plaque psoriasis exists in persons who smoke cigarettes.

Alcohol consumption: Alcohol consumption is considered a risk factor for psoriasis, particularly in young to middle-aged males. See also more psoriasis triggers slides