Copy number variants (CNVs) have been identified as common genomic variants that play a significant role in inter-individual variability. Conversely, rare recurrent CNVs have been found to be causal for many disorders with well-established genotype–phenotype relationships. However, the phenotypic implications of rare non-recurrent CNVs remain poorly understood. Herein, we re-investigated 18,542 cases reported from chromosomal microarray at Greenwood Genetic Center from 2010 to 2022 and identified 15 cases with CNVs involving the 17q25.3 region. We report the detailed clinical features of these subjects, and compare with the cases reported in the literature to determine genotype–phenotype correlations for a subset of genes in this region. The CNVs in the 17q25.3 region were found to be rare events, with a prevalence of 0.08% (15/18542) observed in our cohort. The CNVs were dispersed across the entire 17q25.3 region with variable breakpoints and no smallest region of overlap. The subjects presented with a wide range of clinical features, with neurodevelopmental disorders (autism spectrum disorder, intellectual disability, developmental delay) being the most common features (80%), then expressive language disorder (33%), and finally cardiovascular malformations (26%). The association of CNVs involving the critical gene-rich region of 17q25.3 with neurodevelopmental disorders and cardiac malformation, implicates several genes as plausible drivers for these events.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13039-023-00644-2.