X-LINKED ICHTHYOSIS

Description:

X-linked ichthyosis is a genetic disorder caused by a mutation in the enzyme steroid sulfatase (STS)

Symptoms:

  • Very dry skin
  • Scaling (usually distributed symmetrically)
  • Scales can resemble fish scales; the brown or grey colour can lead to a ‘dirty appearance
  • Short stature
  • Skin abnormalities in the new born
  • Back of the neck is almost always affected
  • Comma-shaped corneal opacities occur in the eyes
  • Undescended testes (crytpchordism)
  • Hyperkeratosis
  • Hypohidrosis
  • Ichthyosis
  • Attention deficit hyperactivity disorder
  • Desquamation improves during summer and deteriorates during dry and cold weather

Causes:

  • Condition coded on the X chromosome
  • Mutation of the enzyme steroid sulfatase (STS)
  • Accumulation of cholesterol sulphate in the outer layer of the skin
  • Dysfunctional skin barrier and retention of the outer skin cells (corneocytes) causing the typical scaling.

Risk Factors:

  • Affecting 1 in 6000 males
  • Gender: Males more affected
  • Age: Occurs at birth or in early infancy

Diagnostic Tests:

  • Based mainly on history and clinical findings
  • Prenatal diagnosis: amniocentesis or chorionic villus sampling
  • Serum protein electrophoresis
  • STS activity assay
  • Molecular testing for DNA deletions or mutations
  • Genetic analysis
  • Southern blot
  • Fluorescent in situ hybridisation (FISH)
  • Polymerase chain reaction

Differential Diagnosis:

  • Asteatotic Eczema
  • Hereditary and Acquired Ichthyosis Vulgaris
  • Lamellar Ichthyosis
  • Pediatric Atopic Dermatitis

Treatments:

  • Rubbing with a pumice stone or exfoliating sponge to remove scale
  • Topical keratolytics containing lactic acid, glycolic acid, salicylic acid and urea
  • Genetic counseling
  • Gene therapy
  • Topical treatment with alpha-hydroxy acids

Medications:

  • Topical isotretinoin
  • Topical tazarotene 0.05% gel
  • Calcipitrol ointment
  • Oral acitretin
  • Oral liarozole
  • acitretin or neotigason

Lifestyle Management:

  • Applying skin softening creams and lotions
  • Regular self-examination