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FOXN1 deficiency

Also known as nude/severe combined immunodeficiency (SCID), this rare primary immunodeficiency disrupts adaptive immunity and is characterized by congenital athymia, congenital alopecia totalis, and nail dystrophy. 

Related gene: FOXN1

Inheritance pattern: Autosomal recessive or autosomal dominant 

FOXN1 deficiency is a rare primary immunodeficiency that disrupts adaptive immunity and is characterized by congenital athymia (lack of a thymus resulting in severe T cell immunodeficiency), congenital alopecia totalis, and nail dystrophy. Also referred to as nude SCID or nude/severe combined immunodeficiency, this disorder is caused by autosomal recessive loss-of-function variants in the FOXN1 gene. Diagnosis relies on testing for FOXN1 variants, which allows for genetic counseling and therapeutic management. Incidence is estimated at 1/1,000,000.

Patients present neonatal or infantile-onset, severe, recurrent, life-threatening infections and low or absent circulating T cells. Additional features reported include erythroderma (severe skin inflammation), lymphadenopathy (enlarged lymph nodes), diarrhea, and failure to thrive.

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Congenital athymia

Congenital athymia is an ultra-rare condition in which children are born without a thymus, causing severe immune deficiency and dysregulation. FOXN1 deficiency is one cause of congenital athymia.

T cells.

SCID Compass

Find educational resources, informative articles, and information about all forms of severe combined immunodeficiency.

This page contains general medical and/or legal information that cannot be applied safely to any individual case. Medical and/or legal knowledge and practice can change rapidly. Therefore, this page should not be used as a substitute for professional medical and/or legal advice. Additionally, links to other resources and websites are shared for informational purposes only and should not be considered an endorsement by the Immune Deficiency Foundation.

Adapted from the IDF Patient & Family Handbook for Primary Immunodeficiency Diseases, Sixth Edition 
Copyright ©2019 by Immune Deficiency Foundation, USA