LAMB3 and junctional epidermolysis bullosa: Recessively inherited JEB is caused by mutations in three genes, LAMA3, LAMB3, or LAMC2, that jointly encode laminin 332 (a heterotrimeric protein consisting of α3, β3, and γ2 chains, also known as laminin 5) and in genes encoding collagen XVII, α6β4, and α3 integrins.