Causes Psoriasis

1 causes

1.1 genetics
1.2 lifestyle
1.3 hiv
1.4 microbes
1.5 medications

causes

the cause of psoriasis not understood, number of theories exist.

genetics

around one-third of people psoriasis report family history of disease, , researchers have identified genetic loci associated condition. identical twin studies suggest 70% chance of twin developing psoriasis if other twin has disorder. risk around 20% nonidentical twins. these findings suggest both genetic susceptibility , environmental response in developing psoriasis.

psoriasis has strong hereditary component, , many genes associated it, unclear how genes work together. of identified genes relate immune system, particularly major histocompatibility complex (mhc) , t cells. genetic studies valuable due ability identify molecular mechanisms , pathways further study , potential drug targets.

classic genome-wide linkage analysis has identified 9 loci on different chromosomes associated psoriasis. called psoriasis susceptibility 1 through 9 (psors1 through psors9). within loci genes on pathways lead inflammation. variations (mutations) of genes commonly found in psoriasis. genome-wide association scans have identified other genes altered characteristic variants in psoriasis. of these genes express inflammatory signal proteins, affect cells in immune system involved in psoriasis. of these genes involved in other autoimmune diseases.

the major determinant psors1, accounts 35%–50% of psoriasis heritability. controls genes affect immune system or encode skin proteins overabundant psoriasis. psors1 located on chromosome 6 in major histocompatibility complex (mhc), controls important immune functions. 3 genes in psors1 locus have strong association psoriasis vulgaris: hla-c variant hla-cw6, encodes mhc class protein; cchcr1, variant wwc, encodes coiled protein overexpressed in psoriatic epidermis; , cdsn, variant allele 5, encodes corneodesmosin, protein expressed in granular , cornified layers of epidermis , upregulated in psoriasis.

two major immune system genes under investigation interleukin-12 subunit beta (il12b) on chromosome 5q, expresses interleukin-12b; , il23r on chromosome 1p, expresses interleukin-23 receptor, , involved in t cell differentiation. interleukin-23 receptor , il12b have both been linked psoriasis. t cells involved in inflammatory process leads psoriasis. these genes on pathway upregulate tumor necrosis factor-α , nuclear factor κb, 2 genes involved in inflammation. recently, first gene directly linked psoriasis has been identified. rare mutation in gene encoding card14 protein plus environmental trigger enough cause plaque psoriasis (the common form of psoriasis).

lifestyle

conditions reported worsening disease include chronic infections, stress, , changes in season , climate. others might worsen condition include hot water, scratching psoriasis skin lesions, skin dryness, excessive alcohol consumption, cigarette smoking, , obesity.

hiv

the rate of psoriasis in hiv-positive individuals comparable of hiv-negative individuals, however, psoriasis tends more severe in people infected hiv. higher rate of psoriatic arthritis occurs in hiv-positive individuals psoriasis in without infection. immune response in infected hiv typically characterized cellular signals th2 subset of cd4+ helper t cells, whereas immune response in psoriasis vulgaris characterized pattern of cellular signals typical of th1 subset of cd4+ helper t cells , th17 helper t cells. hypothesized diminished cd4+-t cell presence causes overactivation of cd8+-t cells, responsible exacerbation of psoriasis in hiv-positive people. psoriasis in hiv/aids severe , may untreatable conventional therapy.

microbes

psoriasis has been described occurring after strep throat, , may worsened skin or gut colonization staphylococcus aureus, malassezia, , candida albicans.

medications

drug-induced psoriasis may occur beta blockers, lithium, antimalarial medications, non-steroidal anti-inflammatory drugs, terbinafine, calcium channel blockers, captopril, glyburide, granulocyte colony-stimulating factor, interleukins, interferons, lipid-lowering drugs, , paradoxically tnf inhibitors such infliximab or adalimumab. withdrawal of corticosteroids (topical steroid cream) can aggravate psoriasis due rebound effect.