Single nucleotide polymorphism in the CHI3L1 gene (rs4950928) in the American Hutterite population was associated with elevated serum concentrations of YKL-40 in asthma (102.7±2.9 μg/L vs. 87.2 μg/L in healthy controls, P = 0.005). The gene discussed is CHI3L1; the disease is asthma.