However, a significant number of Asian and European patients with AD do not display any of the numerous known FLG mutations,3, 4 in particular in the South of Europe.11, 12 In addition, FLG nonsense mutations have not been detected in Ethiopian and South African populations,13, 14 and are not associated with AD in African-American patients.15, 16 Hence, the defect in epidermal barrier functions of patients without FLG mutations, including those of African ancestry, may be associated with other inherited/acquired abnormalities that compromise keratinocyte differentiation.17 This evidence concerns the gene FLG and Alzheimer disease.