Features of clinical course of psoriasis in children depending on halotypes of the VDR gene and vitamin D level

Abstract

Objective. To compare epidemiological and clinical features of psoriasis in children depending on the studied haplotypes of the VDR gene and vitamin D level. Materials and methods. We examined 56 children with psoriasis, 23 boys and 33 girls aged 4–17, the mean age — 12.30±0.45 years. Psoriasis was determined based on clinical findings and generally accepted diagnostic criteria. The severity and extent of body surface involvement were assessed on PASI, PGA, BSA indices. The buccal epithelium, taken from children, served as the material for genotyping. Polymorphic variants of the VDR gene were detected using the polymerase chain reaction technique and the following restriction fragment length polymorphism analysis. The values were calculated using the STATISTICA software package. Results. Five haplotypes of the VDR gene: TTCC, TTAC, TCAA, TCAС, CCAA were detected in children with psoriasis on the back of the study. Boys outnumbered in TTCC group, while girls in others. The age of disease onset in CCAA group was the youngest (5.6±1.69 years) while disease duration was among the longest (6.00±0.67 years). The TCAA haplotype indicated the shortest duration of psoriatic exacerbation (4.2±1.11 weeks), which gradually decreases over the years, and the considerable correlation (r=–0.56) with disease duration takes place. The lowest PGA index was in case of the TCAC haplotype (2.70±0.19), the highest — the TTAC (3.50±0.34) and TTCC (3.31±0.22) haplotypes. PASI and BSA indices were the highest in the presence of the CCAA haplotype. Average serum values of vitamin D in children with psoriasis were insufऀcient except for CCAA group — being optimal and the highest (32.17±4.22 ng/ml). Considerable, large and extremely large correlations between vitamin D serum levels in children with psoriasis and disease duration in the presence of TTCC, TTAC and TCAA haplotypes, between disease intensity and extent of body surface involvement in case of CCAA, TCAA and TCAC haplotypes were detected. Conclusions. Genotyping recognized 5 haplotypes — TTCC, TTAC, TCAA, TCAC, CCAA — that predetermine epidemiological and clinical features of psoriasis. It was concluded that in children with the TCAA haplotype, a younger age at the time of disease onset results in more durable exacerbation with age. In case of CCAA and TTAC haplotypes conversely, psoriatic exacerbation is shorter with age. A decrease in the level of serum vitamin D in children having TTCC, TTAC and TCAA haplotypes leads to an increase of exacerbation duration, while in the presence of TCAA, TCAC, CCAA haplotypes — an increase in the severity of psoriasis.