Frequency of the IL12B rs3212227 polymorphism and associated clinical features in Guatemalan patients with plaque psoriasis: a cross-sectional molecular study

Abstract

Background: Psoriasis is a chronic inflammatory disease in which the IL-12/IL-23 pathway plays a central pathogenic role. Genetic variation within IL12B, which encodes the shared p40 subunit of IL-12 and IL-23, has been associated with psoriasis and psoriatic arthritis in several populations; however, data from Central American populations remain limited. Methods: A cross-sectional observational study was conducted in adult patients with plaque psoriasis attending a tertiary dermatology and rheumatology center in Guatemala. Clinical data were collected using standardized instruments, including the Psoriasis Area and Severity Index (PASI). Psoriatic arthritis was classified using CASPAR criteria, incorporating musculoskeletal ultrasound when indicated. Genomic DNA was extracted from peripheral blood, and the IL12B rs3212227 polymorphism was analyzed using polymerase chain reaction (PCR) followed by Sanger sequencing. Exploratory analyses between genotype and clinical variables were explored using descriptive statistics and appropriate statistical tests. Results: Thirty-five patients were enrolled.  Valid genotyping results were obtained   for nine samples. Genotype frequencies were 88.9% for TT and 11.1% for GG, with a G allele frequency of 11.1%. The mean PASI score was 13.3 ± 8.4, and 34.3% of patients met CASPAR criteria for psoriatic arthritis. No statistically significant associations were observed between rs3212227 genotype and disease severity, age of onset, or presence of psoriatic arthritis. Conclusions: In this Guatemalan cohort, the IL12B rs3212227 polymorphism was infrequent. Although no clinical associations were identified, this study provides the first molecular data describing this variant in a Central American population. These findings contribute to the understanding of genetic diversity in psoriasis and high- light the need for larger, population-based studies to clarify the role of IL12B variation in disease expression and therapeutic response.