Vitamin A and D Status, Selected Genetic Variants, and Allergy-Related Phenotypes: An Exploratory Retrospective Study

Background/Objectives: Vitamins A and D are critical regulators of immune function, and genetic variation in their metabolic pathways may influence vitamin status and immune responses. This study investigated the combined nutrigenetic roles of vitamins A and D and their association with allergy-related phenotypes. Methods: In this retrospective study, 80 individuals were included (40 with allergy-related phenotypes and 40 controls). Genetic polymorphisms in CYP2R1, GC, VDR, and BCMO1 were analyzed. Serum vitamin A and 25(OH)D concentrations were compared between groups, and multivariable analyses were performed to assess the effects of age and sex. Genotype distributions were evaluated using chi-square tests, and co-occurring genetic patterns were explored using the Apriori algorithm (p < 0.05). Results: Both serum vitamin A and 25(OH)D concentrations were significantly lower in the allergy-related phenotypes. Genotype differences were observed for CYP2R1 rs2060793 and BCMO1 rs12934922; however, only CYP2R1 rs2060793 remained significant after FDR correction. Although residual confounding cannot be ruled out, exploratory association rule mining identified co-occurrence patterns involving GC, VDR, and CYP2R1 variants with vitamin D deficiency and BCMO1 variants with vitamin A deficiency. These findings should be considered preliminary and hypothesis-generating rather than evidence of established or causal genetic effects. Conclusions: These preliminary findings indicate potential associations between vitamin status, specific genetic variants, and allergy-related phenotypes. Because of the study's retrospective design and limited sample size, these genetic observations should be regarded as hypothesis-generating and warrant validation in larger, prospectively characterized cohorts.