Supplementary Material for: Atopic Dermatitis in Urban Indonesian Children: A Case-Control Study of the Prevalence of Filaggrin Loss-of-Function Variants and Sociodemographic Factors at a Tertiary Referral Hospital

Introduction: Research on atopic dermatitis (AD) in children has predominantly focused on European and Western populations. Although there is evidence suggesting a connection between sociodemographic and cultural factors and AD, studies involving Asian populations are notably limited. This study profiled filaggrin (FLG) loss-of-function (LOF) variants, estimates their prevalence, and investigates the association between sociodemographic and cultural factors with AD among children in Indonesia as one of the most densely populated developing countries in Asia. Methods: A case control study was conducted at the Pediatric Dermatology Clinic of Dr. Hasan Sadikin General Hospital in Bandung, the capital city of West Java, Indonesia. Children were included from April to December 2022. AD was diagnosed using Hanifin and Rajka criteria. Controls were children without AD of similar age and sex. Sociodemographic data were collected. We sequenced the coding region of FLG using single-molecule molecular inversion probes and next-generation sequencing. Descriptive statistics were used to summarize demographic characteristics. Univariate and multivariate analysis estimated adjusted odds ratios (aOR) and 95% confidence intervals. Results: We enrolled 218 participants. FLG LOF variants were 3.6% in AD and 1.9% in controls; detected variants included c.7487del, c.2282_2285del, and c.1501C>T. Parental history of atopy is significantly associated with children developing AD, with aOR of 6.59 (95% CI: 3.18-13.63) for mothers and aOR 3.86 (95% CI: 1.73-8.62) for fathers. After adjustment, sociodemographic and cultural variables were not statistically significant in multivariate models. Conclusion: In Indonesian children, FLG LOF variants were infrequent, contrasting with European cohorts. Parental atopy remained a strong determinant, and no independent associations with sociodemographic or cultural factors were detected.