dermatologic disorders
Ichthyosis
Inherited ichthyoses
). Some occur in isolation and are not part of a syndrome (eg, ichthyosis vulgaris, X-linked ichthyosis, lamellar ichthyosis, congenital ichthyosiform erythroderma [epidermolytic hyperkeratosis], harlequin ichthyosis). Other ichthyoses are part of a syndrome that involves multiple organs. For example, Sjögren-Larsson syndrome (hereditary intellectual disability and spastic paralysis caused by a defect in fatty aldehyde dehydrogenase) is an Autosomal Recessive condition with skin and extracutaneous organ involvement. Another example of a condition with skin and extracutaneous organ involvement is keratitis ichthyosis deafness (KID) syndrome, which is characterized by vascularizing keratitis, ichthyosis, and sensorineural hearing loss and caused by mutations in the Disorder Disorder Prevalence Prevalence Gene Mutation Gene Mutation Onset Onset Type of Scale Type of Scale Distribution Distribution Associated Clinical Findings Associated Clinical Findings Nonsyndromic ichthyoses Nonsyndromic ichthyoses Ichthyosis vulgaris ( Autosomal Dominant ) Prevalence varies by ethnicity: 10:792 in a study of English schoolchildren versus 1:5025 in a Russian cohort study† FLG Childhood Fine Usually back and extensor surfaces but not intertriginous surfaces Usually many markings on palms and soles Atopy Keratosis Pilaris None Asthma None X-Linked Recessive ichthyosis Prevalence varies by ethnicity: 1:1500 males in a United States cohort study versus about 1:4000–6000 in European cohort studies† STS Birth or infancy Large, dark, usually coarse (may be fine) Prominent on neck and trunk Normal palms and soles Corneal opacities Cryptorchidism None Testicular Cancer None Congenital Autosomal Recessive ichthyoses Congenital Autosomal Recessive ichthyoses Lamellar ichthyosis 1:300,000 Many, eg,TGM1,ABCA12,ALOXE3 Birth Large, coarse, sometimes fine Most of body Variable palm and sole changes Entropion and Ectropion None Hypohidrosis with heat intolerance Alopecia None Congenital ichthyosiform erythroderma* 1:300,000 Same as lamellar ichthyosis Birth Thick, warty At birth: Redness and blisters In adulthood: Scaling Most of body Especially warty in flexural creases Bullae, frequent skin infections Harlequin ichthyosis < 1:100,000 ABCA12 Birth Thick, porcelain-like, body armor–like with deep fissures Entire body Ectropion, lip eversion (eclabion), nasal hypoplasia, polyhydramnios, flexion deformities, dehydration, severe infection, respiratory insufficiency * This disorder is also called bullous congenital ichthyosiform erythroderma, or epidermolytic hyperkeratosis. Mutations are spontaneous in about 50% of cases. †Gutiérrez-Cerrajero C, Sprecher E, Paller AS, et al: Ichthyosis.Nat Rev Dis Primers9(1):2, 2023. doi: 10.1038/s41572-022-00412-3 