X-linked ichthyosis
X-linked ichthyosis (abbreviated XLI) 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.[9] Heart rhythm abnormalities in individuals with XLI tend to co-occur with disorders of the gastrointestinal tract, and are likely to result from steroid sulfatase deficiency.[15] Individuals with XLI can exhibit intellectual disability, although this is thought to be due to deletions encompassing neighboring genes (e.g. VCX) in addition to STS.[16] The skin and medical conditions associated with XLI are likely to be due to perturbed basement membrane function and abnormal interactions with the extracellular matrix.[23] For this reason, XLI most commonly affects males, although individuals with numeric abnormalities of the sex chromosomes (45,X and 47,XXY) who also carry STS deletions or mutations would be exceptions to this rule.Due to random segregation of the chromosomes during gametogenesis, each pregnancy will be subject to the same probabilities, regardless of the number of previously affected or unaffected offspring.[27] XLI can be suspected based on clinical findings, although symptoms can take varying amounts of time to become evident, from a few hours after birth, up to a year in milder cases.[30] Timber Pharmaceuticals is planning on conducting a phase 3 trial of its investigational topical isotretinoin product in the second quarter of 2022 for the treatment of congential ichthyosis.
SpecialtyMedical geneticshereditary deficiencysteroid sulfatasecontiguous gene syndromesAncient GreekAtrial fibrillationatrial fluttergastrointestinal tractarrhythmiainterventricular septuminteratrial septumCryptorchidismautismattention deficit hyperactivity disordermemoryintellectual disabilitybasement membraneextracellular matrixhemostasisobstetricianX-linked conditionX-inactivationhemizygousheterozygousobligate carriergametogenesisestrone sulfatedehydroepiandrosterone sulfateestrogencholesterol sulfatedermatologistPrenatal diagnosisIchthyosisCarvajal syndromeOnline Mendelian Inheritance in ManBibcodeeMedicineDiseasesDBOrphanetCongenitalintegumentskin diseaseGenodermatosisCongenital ichthyosiserythrokeratodermiaIchthyosis vulgarisCongenital ichthyosiform erythrodermaEpidermolytic hyperkeratosisLamellar ichthyosisHarlequin-type ichthyosisNetherton syndromeCHIME syndromeSjögren–Larsson syndromeIchthyosis bullosa of SiemensIchthyosis follicularisIchthyosis prematurity syndromeIchthyosis–sclerosing cholangitis syndromeNonbullous congenital ichthyosiform erythrodermaIchthyosis linearis circumflexaIchthyosis hystrixEBS-WCEBS-DMEBS-OGEBS-MDEBS-MPGeneralized atrophicJEB-PACostello syndromeKindler syndromeLaryngoonychocutaneous syndromeSkin fragility syndromeEctodermal dysplasiaNaegeli syndromeDermatopathia pigmentosa reticularisHay–Wells syndromeHypohidrotic ectodermal dysplasiaFocal dermal hypoplasiaEllis–van Creveld syndromeRapp–Hodgkin syndromeElasticConnectiveEhlers–Danlos syndromeCutis laxaGerodermia osteodysplasticaPopliteal pterygium syndromePseudoxanthoma elasticumVan der Woude syndromeHyperkeratosiskeratinopathydiffuseDiffuse epidermolytic palmoplantar keratodermaDiffuse nonepidermolytic palmoplantar keratodermaPalmoplantar keratoderma of SybertMeleda diseaseconnexinBart–Pumphrey syndromeClouston's hidrotic ectodermal dysplasiaVohwinkel syndromeCorneodermatoosseous syndromeplakoglobinNaxos syndromeScleroatrophic syndrome of HuriezOlmsted syndromeCathepsin CPapillon–Lefèvre syndromeHaim–Munk syndromeCamisa diseaseFocal palmoplantar keratoderma with oral mucosal hyperkeratosisFocal palmoplantar and gingival keratosisHowel–Evans syndromePachyonychia congenitaPachyonychia congenita type IPachyonychia congenita type IIStriate palmoplantar keratodermaTyrosinemia type IIpunctateAcrokeratoelastoidosis of CostaFocal acral hyperkeratosisKeratosis punctata palmaris et plantarisKeratosis punctata of the palmar creasesSchöpf–Schulz–Passarge syndromePorokeratosis plantaris discretaSpiny keratodermaPalmoplantar keratoderma and spastic paraplegiadesmoplakin