Clinical and Genetic Significance of Chromosomal Microarray Screening of Asymptomatic Newborns

INTRODUCTION: In South Korea, low-resolution chromosomal microarray analysis (LR-CMA) is frequently used as a screening tool to identify chromosomal anomalies in asymptomatic newborns. However, its clinical utility remains controversial. METHODS: We retrospectively analyzed 99 asymptomatic newborns who underwent diagnostic CMA following abnormal LR-CMA screening results at a single tertiary hospital between 2019 and 2024. Clinical features, copy number variant (CNV) findings, and follow-up outcomes were assessed. RESULTS: Among the 99 patients (57.6% male), the median ages at the initial and last visits were 0.3 and 1.0 years, respectively. A total of 171 CNVs were identified, of which 85 (49.7%) were classified as pathogenic or likely pathogenic. Overall, 70 of 99 (70.7%) patients harbored microduplication or deletions with syndromic implications. Developmental delay was identified in 10 (10.1%) patients. Notably, no significant associations were found between CNV pathogenicity and prenatal history, presence of anomalies, developmental delays, or growth parameters. CONCLUSIONS: Although a high rate of clinically significant CNVs was detected through LR-CMA screening, only a minority of asymptomatic newborns exhibited developmental concerns within the observed follow-up period. These findings suggest that while LR-CMA may identify genetic alterations of interest, its routine use in asymptomatic newborns warrants careful consideration of clinical relevance and potential psychosocial impact.