Exploring Patient Reported Outcomes in Inherited Ichthyosis

The goal of this observational study is to learn about the presence of extracutaneous manifestations in patients with congenital ichthyosis. The main question it aims to answer is: \- Do patients with congenital ichthyosis experience extracutaneous manifestations? Participants will fill in questionnaires in which the investigators will explore whether patients experience extracutaneous manifestations, and if so what these manifestations entail. Examples of such questions are whether patients experience (joint) pain or whether they experience hindrance due to their complaints.