Psoriasis vulgaris: a genetic approach

Area of Science:

• Genetics
• Dermatology
• Immunology

Background:

• Psoriasis is a common inflammatory skin disease with a suspected genetic basis.
• Previous studies, including twin and family analyses, suggested a significant hereditary component.

Purpose of the Study:

• To investigate the genetic underpinnings of psoriasis.
• To identify specific genetic markers associated with psoriasis susceptibility.

Main Methods:

• Twin studies and population-based analyses were used to estimate heritability.
• Serological studies and human leukocyte antigen (HLA) typing were performed to identify genetic associations.
• Family-based linkage analysis using restriction fragment polymorphisms (RFLP) on chromosome 6 was initiated.

Main Results:

• Psoriasis concordance in monozygotic twins was 65-72%, and heritability approached 90-100% in older twin pairs.
• Strong associations were found with HLA class I (B locus) and class II (D locus) genes (relative risk 8-12).
• A significant association with HLA-Cw6 (relative risk ~24) was identified, likely in linkage disequilibrium with other associated HLA genes.

Conclusions:

• Psoriasis exhibits substantial genetic heritability, supporting a significant inherited predisposition.
• Specific HLA alleles, notably HLA-Cw6, are strongly associated with psoriasis risk.
• Further genetic linkage analysis is underway to pinpoint specific psoriasis susceptibility genes on chromosome 6.