Upon adjustment for age, sex, BMI, smoking, drinking, exercise, education, income, metabolic syndrome and vitamin D level, the trend analyses showed significant negative linear correlations between serum Zn levels and total, D. farina-, cockroach-, and dog-specific IgE levels (p-value for linear trend = 0.004, 0.006, 0.027, and < 0.001, respectively) (Fig. 2). The gene discussed is IGHE; the disease is metabolic syndrome.