Case Report: Transient severe T cell lymphopenia in a patient with Cornelia de Lange Syndrome captured by TREC screening.

Cornelia de Lange Syndrome (CdLS) is a rare multisystem disorder characterized by craniofacial dysmorphism, growth restriction, limb anomalies, intellectual disability, and mild to moderate immune abnormalities. We present the case of a newborn female with CdLS who was found to have severe transient T-cell lymphopenia following abnormal newborn T-cell receptor excision circle (TREC) screening. She was treated with immunoglobulin replacement and antimicrobial prophylaxis. She experienced normalization of T cells and no severe infections over a two-year period. To our knowledge, this is the first detailed report of a case of CdLS presenting with profound T-cell lymphopenia identified by newborn screening, underscoring the utility of TREC screening in syndromic infants and the need for further study of immune defects in CdLS.