TABLE II.

Non-SCID disorders with low T-cell numbers potentially identified by TREC-based newborn screening

Disorder
Combined immunodeficiency, including single-gene and syndromic disorders of T-cell development, such as the following: Ataxia-telangiectasia Disorders of folate absorption or metabolism MHC class I and II defects Nijmegen breakage syndrome Trisomy 21 and other chromosomal aneuploidies
Disorders of thymic stromal cell development, such as the following: CHARGE syndrome DiGeorge syndrome (complete or partial) Other disorders of thymic stromal cell development (eg, pathogenic variants in genes such as FOXN1, FOXI3, TBX1, TBX2, CHD7, or PAX1)
Idiopathic T-cell lymphopenia
Secondary T-cell lymphopenia due to: Advanced in utero HIV infection Chylous effusions, spontaneous or postsurgery Gastrointestinal or cardiac malformations Hydrops Maternal immunosuppressive medications Preterm birth, very low birth weight