The ichthyoses are a group of lifelong genetic disorders that share characteristics of generalized skin thickening, scaling and underlying cutaneous inflammation. The vast majority are orphan disorders and are associated with extremely poor quality of life related to social ostracism from altered appearance, associated itchiness and discomfort, and functional limitations from the skin disease. Among the more common "orphan" forms of ichthyosis are autosomal recessive congenital ichthyosis (ARCI; includes lamellar ichthyosis/LI and congenital ichthyosiform erythroderma/CIE), Netherton syndrome (NS) and epidermolytic ichthyosis (EI). However, there are dozens of other syndromic and non-syndromic ichthyotic disorders as well. Therapy is time-consuming for patients or parents and is supportive, focusing on clearance of the scaling. There are no therapies based on our growing understanding of what causes the disease. We have recently found marked elevations in Th17/IL-23 pathway cytokines and chemokines in the skin of individuals with ichthyosis, most similar to the inflammatory pattern of psoriasis. While the significance of the high expression of Th17/IL-23 pathway genes across all forms of ichthyosis studied to date is unknown, the high expression of genes of the Th17/IL-23 pathway in psoriasis is thought to be causative for the disease manifestations. We propose that IL-12/IL-23 -targeting therapeutics will safely suppress the inflammation and possibly the other features of ichthyosis, improving quality of life. As a proof-of-concept study, we propose to treat children (6 years of age and higher) and adults with ichthyotic disorders with ustekinumab in an open-label trial to serially assess clinical response to and safety of ustekinumab for this group of disorders.