Background Psoriasis is a common chronic inflammatory disease of the skin and joints. It can
manifest itself as various phenotypes. It is a systemic, inflammatory disease in which an increased
release of pro-inflammatory cytokines from immune-related cells and chronic activation of the innate
and adaptive immune system causes longterm damage to multiple tissues and organs. It has been
associated with numerous comorbidities including rheumatological , cardiovascular and psychiatric
complications.
Special attention should be given to the genetic aspect in the pathogenesis of the psoriasis.
Keywords: Psoriasis, Cytokines, Comorbidities,Inflammatory,Genetic
Introduction
Psoriasis is an immune-mediated polygenic
skin disorder, various environmental triggering
factors, e.g. trauma, infections, medications,
may elicit disease in predisposed individuals
(1).
It is a lifelong disease with spontaneous
remissions and exacerbations and characterized
clinically by sharply demarcated dull red scaly
plaques affecting mainly the extensor
prominences, scalp, and the sites of trauma.
While the disease has several distinct yet
overlapping phenotypes, by far the most
common is chronic plaque psoriasis which
affects about 90% of patients (2).
Characteristic histopathological findings
include uniform elongation of the rete ridges,
dilated blood vessels, thinning of the
suprapapillary plate, intermittent parakeratosis,
the presence of occasional neutrophil
aggregates in the epidermis, and perivascular
infiltration of lymphocyte (3).
Psoriasis is a bi-modally distributed disease
with one major age of onset at 20–30 years of
age as well as a later smaller peak of onset at
50–60 years.It affects both males and females,
with earlier onset in females and those with a
family history (4).
A higher incidence of psoriasis within families
has been reported worldwide. In twin
studies, monozygotic twins have a
susceptibility to psoriasis that is 2–3 times
higher than that of double zygotic twins.
Children have a 20% chance of developing
psoriasis if one parent is affected and 65% if
both parents are affected (5).
A total of 36 genes are thought to account for
22% of psoriasis heritability, and more than 16
genetic loci have confirmed association with
psoriasis susceptibility. HLA-Cw6 on
chromosome 6 is considered to be the risk
variant in the PSOR1 Review of literature 5
susceptibility locus that confers the greatest
risk of early onset psoriasis (6). |
