Palmar hyperlinearity in early childhood atopic dermatitis is associated with filaggrin mutation and sensitization to egg.

Abstract

Palmar hyperlinearity is a typical clinical feature of Filaggrin gene (FLG) null mutations. There are reports of FLG mutations and allergic sensitization; however, reports on the relationship between palmar hyperlinearity to sensitization are limited. This study aimed to examine the association between palmar hyperlinearity and sensitization in atopic dermatitis (AD) children. This cross-sectional, case-control study included children ˂ 6years old with moderate-severe AD whose parents consented for mutation analysis and photographic documentation. Each child underwent genotyping to detect the eight most prevalent FLG mutations in the Japanese population: R501X, 3321delA, S1695X, Q1701X, S2554X, S2889X, S3296X, and K4022X. Clinical features and parameters including egg-specific IgE were examined, and palm photographs were evaluated by 12 trained dermatologists blinded to genotyping results. Of the 57 patients (age range, 2months to 5years; median, 22months), 16 were heterozygotes and three were compound heterozygotes. Palmar hyperlinearity, as recognized by more than two-thirds of dermatologists, was significantly associated with FLG mutation (P=0.002, OR=6.98, 95% CI=2.1-23.7), and this association was observed especially in children over 2years. Cross-shaped crease of the thenar eminence, as known in previous reports, also demonstrated significant correlation with FLG mutation. When the children were divided according to the presence or absence of palmar hyperlinearity, the egg white-specific IgE was significantly higher in the hyperlinearity group (55.9 vs 18.3IU/mL, P<0.05). Palmar hyperlinearity indicates possible inherited barrier abnormalities of the skin in early childhood. Its identification may help to predict a more accurate prognosis, such as sensitization.