Haptoglobin expression correlated negatively with asthma/rhinoconjunctivitis (β = −0.39, p = 0.05), and low 25(OH)D levels (<30 ng/mL) were associated with claudin-1 (β = −2.04, p = 0.0077) and occludin-1 (β = 0.43, p = 0.002). This evidence concerns the gene CLDN1 and asthma.