Severe Combined Immunodeficiency due to NHEJ1 Deficiency

**Semantic type:** Disease or Syndrome

**Definition:** An autosomal recessive condition caused by mutation(s) in the NHEJ1 gene, encoding non-homologous end-joining factor 1. It is characterized by severe combined immunodeficiency that is T-cell negative, B-cell negative, NK-cell positive. Microcephaly, growth retardation, and sensitivity to ionizing radiation are also characteristic of this disease.

**Synonyms:** - Cernunnos / XLF deficiency - NHEJ1-SCID