Severe combined immunodeficiency due to FOXN1 deficiency

What is Severe combined immunodeficiency due to FOXN1 deficiency?

A rare, genetic, primary immunodeficiency due to a defect in adaptive immunity characterized by the triad of congenital athymia (resulting in severe T-cell immunodeficiency), congenital alopecia totalis and nail dystrophy. Patients present neonatal or infantile-onset, severe, recurrent, life-threatening infections and low or absent circulating T cells. Additional features reported include erythroderma, lymphoadenopathy, diarrhea and failure to thrive.

Other condition names

  • Alymphoid cystic thymic dysgenesis
  • Nude/SCID
  • Nude/severe combined immunodeficiency
  • SCID due to FOXN1 deficiency
  • Severe T-cell immunodeficiency-congenital alopecia-nail dystrophy syndrome
  • Winged helix deficiency

Inheritance type

Autosomal dominant, Autosomal recessive


  • Worldwide: <1 in 1,000 000

Age of Onset

  • Infancy
  • Neonatal
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