The polygenetic nature of dermatitis is also evident in mice, with marked differences between BALB/c and C57BL/6J strains in the magnitude of skin inflammation and the functional genes involved.16, 25 Herein filaggrin-deficient mice were generated on a BALB/c background, a strain predisposed to type 2/type 17–associated inflammation.17, 18, 19, 40, 41, 42 BALB/c Flgft/ft mice have spontaneous AD-like skin inflammation and pulmonary inflammation unlike the filaggrin mutant on the C57BL/6J background10 and the Flg deletion knockout C57BL/6 mouse.43 Here, FLG is linked to dermatitis.