We use tentative criteria as follows: intrinsic AD is defined as serum IgE levels ≤ 200 kU/L or 200 < IgE ≤ 400 plus class 0 or 1 of IgE specific to Dermatophagoides pteronyssinus or Dermatophagoides farinae, and extrinsic AD is defined as 400 < IgE levels or 200 < IgE ≤ 400 plus class 2 or more of the specific IgE [21]. The gene discussed is IGHE; the disease is Alzheimer disease.