The goal of this study is to identify important biological pathways involved in a variety of ichtyosis, using transcriptomic and proteomic techniques, with the aim of guiding the development of new therapeutis.

Inclusion Criteria:

• Aged 15-80 years old
• Having an ARCI or EI, confirmed by a molecular diagnosis of a mutation in at least one of the following genes: TGM1, ALOX12B, NIPAL4, ABCA12, keratin 1 and keratin 10)
• Having stopped all topical treatments in at least 1% of the total body surface (equivalent to one palm of the hand of the patient), at least 8 days before the skin biopsy (which will be performed on this untreated area).
• Patients having a molecular diagnostic of genetic ichtyosis
• No contraindication to skin biopsy
• Health insurance coverage
• Signature of written consent

Exclusion Criteria:

• Aged less than 15 of over 80 years old
• Ichtyosis without a molecular confirmed diagnosis or with a different diagnosis
• History, in the 8 previous days, of any topical treatment on the area intended for the skin biopsy.
• No health insurance coverage
• Pregnant or breastfeeding woman
• Patient under guardianship or curatorship
• Patient under State Medical Assistance (AME)