The Genetic Architecture of Congenital Heart Disease in Neonatal Intensive Care Unit Patients-The Experience of University Medical Centre, Ljubljana.

Congenital heart disease (CHD) is the most commonly detected congenital anomaly and affects up to 1% of all live-born neonates. Current guidelines support the use of chromosomal microarray analysis (CMA) and next-generation sequencing (NGS) as diagnostic approaches to identify genetic causes. The aim of our study was to evaluate the diagnostic yield of CMA and NGS in a cohort of neonates with both isolated and syndromic CHD. The present study included 188 infants under 28 days of age with abnormal echocardiography findings hospitalized at the Department of Neonatology, UMC Ljubljana, between January 2014 and December 2023. Phenotypic data were obtained for each infant via retrospective medical chart review. We established the genetic diagnosis of 22 distinct syndromes in 17% (32/188) of neonates. The most frequent genetic diagnoses in diagnosed cases were microdeletion and CHARGE syndromes, followed by Noonan syndrome and Williams syndrome. In addition, we detected variants of uncertain significance in 4.8% (9/188) of neonates. Timely genetic diagnosis is important for the detection of syndrome-related comorbidities, prognosis, reproductive genetic risks and, when appropriate, genetic testing of other family members.