A novel microdeletion syndrome involving 17q23.3 region in a child with short stature and multiple congenital anomalies: A Case Report.

Microdeletion syndromes are rare chromosomal abnormalities causing diverse clinical features due to gene dosage imbalances. Deletions in chromosome 17q23.3 have been linked to neurodevelopmental and growth disorders, although the genotype-phenotype correlations remain unclear. An eight-month-old male baby presented with short stature, low-set ears, cardiac anomalies, and multiple congenital malformations. He was born via C-section due to intrauterine growth restriction and exhibited craniofacial dysmorphism, lymphatic vessel dysplasia, micropenis, undescended testes, atrial septal defect, and subclinical hypothyroidism. The phenotype raised clinical suspicion of Noonan Syndrome. However, exome sequencing revealed no pathogenic variants in RASopathy-related genes. Copy number variant (CNV) analysis identified a ∼1.5 Mb deletion on chromosome 17q23.3, affecting 30 genes, including TANC2, which serves as the primary breakpoint gene and plays an essential role in synaptic development. This case highlights the role of CNV analysis in patients suspected of having Noonan Syndrome with negative single-gene testing and suggests an expanded phenotypic spectrum associated with 17q23.3 microdeletion.