In Jack Russell Terriers, [16] related the lamellar ichthyosis to a LINE-1 insertion in the transglutaminase 1 (TGM1) gene, which encodes an enzyme with a role in cornified envelope formation, and 30–40% of humans with non-epidermolytic (lamellar) ichthyosis present mutations in this gene [79]. Here, TGM1 is linked to ichthyosis.