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Complement phenotypes in patients with psoriasis
R J Wyatt1, C Wang, E C Hudson
1Department of Pediatrics, University of Tennessee, Memphis.
Insights
The C4*A6 allele, linked to HLA B17, is significantly more common in Caucasian psoriasis patients than controls, suggesting a genetic link to psoriasis development. This finding highlights complement system variations in the disease.
Area of Science:
- Immunogenetics
- Dermatology
- Human Genetics
Background:
- Psoriasis is a chronic inflammatory skin disease with a complex genetic component.
- Complement system proteins, including C4A, C4B, factor B (Bf), and C3, play roles in immune responses.
- Previous studies suggest associations between certain Human Leukocyte Antigen (HLA) alleles and psoriasis.
Purpose of the Study:
- To investigate the phenotype frequencies of complement proteins C4A, C4B, Bf, and C3 in Caucasian patients with psoriasis.
- To determine if specific complement protein alleles are associated with psoriasis in this population.
- To explore the relationship between complement protein alleles and known psoriasis-associated HLA alleles.
Main Methods:
- Phenotype frequencies of complement proteins C4A, C4B, Bf, and C3 were analyzed.
- A cohort of 49 Caucasian patients with psoriasis was compared to healthy Caucasian controls.
- Statistical analysis, including relative risk calculation, was performed to assess associations.
Main Results:
- The C4*A6 allele was found in 26.6% of psoriasis patients versus 5.4% of controls (p < 0.001, RR = 6.28).
- A significant reduction in the C4B*2 allele frequency was observed in patients.
- No significant differences were found for Bf or C3 phenotype frequencies; a non-significant increase in Bf*F was noted.
Conclusions:
- The C4*A6 allele, known to be in linkage disequilibrium with HLA B17 (associated with psoriasis), shows a strong association with psoriasis in Caucasian individuals.
- Complement C4B*2 allele deficiency may also be associated with psoriasis.
- These findings suggest that specific complement protein gene polymorphisms, particularly C4A variants, contribute to psoriasis susceptibility.
Abstract:
Phenotype frequencies for the complement proteins C4A, C4B, Bf (factor B) and C3 were performed for 49 Caucasian patients with psoriasis. The C4*A6 allele was present in 26.6% of the patients as compared to 5.4% of healthy regional Caucasian controls, p less than 0.001, relative risk = 6.28. The C4*A6 allele is known to be in linkage disequilibrium with the HLA B17 allele and to produce a non-functional gene product when it occurs with the B17 allele. HLA B17 is known to be associated with psoriasis in many Caucasian populations. Additional findings in the present study were a significant reduction in the C4B*2 allele frequency, a non-significant increase in the Bf*F allele frequency and no difference for Bf or C3 phenotype frequencies in the patients with psoriasis as compared to the controls.