Xerosis is not included in this grouped analysis as xerosis as a skin sign (meaning clinically dry skin in the absence of scaling) is not independently associated with FLG null mutations.17 The equivalent odds ratios for FLG-related skin features are > 100 in FLG null homozygotes and 6·3 in FLG heterozygotes, compared with 1·0 in wild-type individuals. The gene discussed is FLG; the disease is Dry skin.