As for nickel sensitization rates in both groups, this event could be at least partially explained by the idea that AD is now considered more like a complicated and heterogeneous immunological entity, with some cases, defined as “intrinsic”, of AD patients having normal IgE levels, minimum to absent barrier dysfunction and a mainly Th1-driven skin immune response [13,35,36]. The gene discussed is IGHE; the disease is Alzheimer disease.