Association of Human Leukocyte AntigenCw6 in Psoriasis Patients with Disease Severity and Morphological Patterns: A Cross-control Study in a Tertiary Care Referral Centre in Eastern India

Abstract

Introduction: Psoriasis is a multifactorial disorder in which genetic and environmental factors play an essential role in disease pathogenesis. The Human Leukocyte Antigen-Cw6 (HLA-Cw6) allele has shown the strongest genetic association with this condition across several populations studied. Aim: To estimate the risk of HLA-Cw6 association with psoriasis compared to the control group and its association with the severity of psoriasis expressed as Psoriasis Area and Severity Index (PASI) score and morphological patterns. Materials and Methods: A cross-control study was conducted from March 2014 to February 2015 in a tertiary care centre in the eastern part of India. All patients who were diagnosed clinically as psoriasis and gave written informed consent were included in the study. Healthy controls were taken to compare the HLA-Cw6 after duly signing the informed consent for detailed history, clinical examination, PASI score, and digital photographs of lesions were taken. A blood sample was taken from patients and the control for HLA-Cw6 typing by sequencespecific Polymerase Chain Reaction (PCR) method. Data was analysed by appropriate statistical test (Chi-square test) using R statistical software. Results: A total of 100 patients with psoriasis and 100 controls were recruited, of which 61 were positive for HLA-Cw6 among the psoriasis group and nine in the control group. Positivity of the HLA-Cw6 allele was significantly higher in psoriasis cases (n=61) compared to normal individuals (n=9) (p-value: 1.79×10-15, OR: 15.8148, 95% CI: 7.15-34.99). It was also observed that HLA-Cw6 positive individuals had a more severe form of the disease, determined by a PASI score >6 (p-value: 0.0494, OR: 2.22, 95% CI: 0.96-5.15), and significant involvement of scalp psoriasis (p-value: 0.0054, OR: 13.125, 95% CI: 1.55-111.42). However, no significant association of HLA-Cw6 was seen with positive family history, nail involvement, and joint pain (arthralgia). Conclusion: The HLA-Cw6 positivity was associated with a more severe form of disease and scalp psoriasis.

Keywords

• morphological patterns
• nail involvement
• polymerase chain reaction
• psoriasis area and severity index