CYP4F22 and pustular psoriasis: This included Sanger sequencing of the entire coding sequences of SPINK5 and ADAM metallopeptidase domain 17 (ADAM17), as well as 8 genes known to cause autosomal recessive congenital ichthyosis (NIPAL4, CYP4F22, ALOXE3, ALOXE12B, TGM1, PNPLA1, ABCA12, CERS3, FATP4, and ABHD5) and pustular psoriasis (CARD14 and IL36RN).