The consequences of being contact allergic have been assessed in a Danish study with 2270 participants from a population-based study followed up ~5 years after a patch test; even though a history of atopic dermatitis was the strongest risk factor for persistent or incident hand dermatitis (OR 9.0), filaggrin (FLG) null mutation (OR 3.0), and contact sensitisation (OR 2.5) were also independently associated with persistent hand dermatitis [8]. This evidence concerns the gene FLG and hand eczema.