Heterozygosity for FLG null mutations augments the risk of dry skin in both women and men (OR = 2.7–7.4) [238,239], and wild-type individuals with 10 filaggrin repeats (10/10 genotype) have drier skin (self-perceived) than those with 12 repeats (12/12 genotype) [240], including in AD [166,241]. Here, FLG is linked to Alzheimer disease.