X-linked ichthyosis X-linked ichthyosis X-linked ichthyosis (XLI) (also known as ") is a skin condition caused by the hereditary deficiency of the steroid sulfatase (STS) enzyme that affects 1 in 2000 to 1 in 6000 males. XLI manifests with dry, scaly skin and is due to deletions or mutations in the "STS" gene. XLI can also occur in the context of larger deletions causing contiguous gene syndromes. Treatment is largely aimed at alleviating the skin symptoms. The term is from the Ancient Greek 'ichthys' meaning 'fish'. The major symptoms of XLI include scaling of the skin, particularly on the neck, trunk, and
Heterogeneous condition case, in which it is not possible to speak about a single disease associated to the clinical course of the patient. While the term "medical condition" generally includes mental illnesses, in some contexts the term is used specifically to denote any illness, injury, or disease except for mental illnesses. The Diagnostic and Statistical Manual of Mental Disorders (DSM), the widely used psychiatric manual that defines all mental disorders, uses the term "general medical condition" to refer to all diseases, illnesses, and injuries except for mental disorders. This usage is also commonly seen in the psychiatric literature. Some health insurance policies