 (N/J) x (N/J) = 50% N/J, 25% N/N, and 25% J/J

(N/N) x (N/J) = 50% N/N and 50% N/J

Foals which are homozygous recessive (J/J) do not make it to reproductive age, so cannot be a parent.Carriers (N/J) do not display symptoms and have normal skin.Mutations in the genes LAMB3, LAMC2, and COL17A1, are the cause of JEB.