Hyperlinear Palms As a Phenotypic Marker of Food Allergy

Hyperlinear palms (HP) are associated with keratin abnormalities and can be a feature of icthyosis vulgaris (IV), atopic dermatitis (AD), and filaggrin (FLG) mutations. Previous studies by our group have demonstrated keratin (KRT) and FLG abnormalities in skin tape strips (STS) of children with AD with food allergy (AD+FA+). However, there have been no studies assessing HP association with FA. Twenty-two nonatopic (NA) controls, AD children with FA (AD+FA+, n=26) and AD children without FA (AD+FA-, n=21) were examined for HP, IV and scored for AD severity. Food skin prick tests and STS lipidomic and proteomic analysis were performed. To compare differences in HP, chi-square and ANOVA test were used for categorical variables and continuous variables, respectively. HP were identified in thirteen AD+FA+, four AD+FA-, and one NA subject (p<0.001). The occurrence of HP remained significantly greater in AD+FA+ than in AD+FA- children after adjustment for AD severity (p=0.03). Correlation with IV and FA was not found. HP correlated with peanut skin test wheal size (p<0.01). Additionally, all AD subjects (AD+FA+ and AD+FA) with HP had significantly greater KRT5, a marker of undifferentiated keratinocytes, expression in STS (p<0.05), and significantly reduced EOS CER/NS CER ratio (w-esterified fatty acid sphingosine ceramide/nonhydroxy fatty acid sphingosine ceramide) (p<0.01). A significant association between HP and FLG mutations was also found (p<0.005). Clinicians should examine AD children for HP, as this may be a phenotypic marker of FA. HP may be due to keratin dysregulation, skin lipid abnormalities, and FLG mutations.