The top-ranked DMP, cg03284554, located in the promoter region of the heparan-α-glucosaminide N-acetyltransferase (HGSNAT) gene on chromosome 8q21, was consistently hypermethylated in asthma-affected twins compared to their unaffected co-twin (mean Δβ = 0.041, P = 6.87E-06, permuted empirical P < 0.0001). This evidence concerns the gene HGSNAT and asthma.