Keratosis follicularis spinulosa decalvans (KFSD) is a rare, inherited, skin condition. KFSD is a form of ichthyoses, a group of inherited conditions of the skin in which the skin tends to be thick and rough, and to have a scaly appearance. The face, neck, and forearms are frequently involved. The thickening of the skin is accompanied by the loss of eyebrows, eyelashes, and hair on the face and head. Allergic reactions (atopy), reduced tolerance of bright light (photophobia), and inflammation of the eye's cornea (keratitis) may also occur. KFSD is thought to be caused by mutations in the SAT1 gene and inherited in an X-linked manner. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.