X-linked Ichthyosis - steroid sulfatase deficiency

  • Incidence 1:6000
  • X-linked recessive
  • Mutation in ARSC1, encodes steroid sulfatase → failure to degrade cholesterol sulfate for the epidermal lipid barrier
    • Failure to form epidermal lipid barrier
    • Retained corneodesmosomes
  • Female carriers do not show ichthyosis because gene is located at the distal tip of the X chromosome that escapes X inactivation
    • Maternal carriers do show decreased serum estriol
  • “Dirty scale” accentuated on the neck/pre-auricular, trunk, legs and feet sparing palms, central face, flexural areas
    • More widespread than ichthyosis vulgaris
    • Involves neck and pre-auricular area (differentiate from ichthyosis vulgaris)
    • May spare flexural areas like in ichthyosis vulgaris
  • Associated features:
    • Asymptomatic corneal opacities
    • Hypogonadism/cryptorchidism
    • ADHD/autism
    • Prolonged labor/failure to progress (low placental estrogen)
  • Contiguous deletion syndromes (Kallman syndrome, X-linked recessive chondrodysplasia punctata)