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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.

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