FOXN1 deficiency

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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