Deletion of the short arm of chromosome 20 in a girl with neurodevelopmental disorders

Introduction: Deletions of the short arm of chromosome 20 are a relatively rare chromosomal abnormality, with few reported cases in the literature and a wide range of clinical manifestations.Objective: To describe the phenotypic features of a patient with an unusual deletion in the distal region of the short arm of chromosome 20.Results: The patient exhibited severe neurodevelopmental delay, cardiac, gastrointestinal, and cerebral malformations, as well as multiple dysmorphic features. A high-resolution karyotype, analyzing 20 metaphases with GTG banding, detected a terminal deletion in the short arm of chromosome 20, with the karyotype 46,XX,del(20)(p12.2). Cytogenetic analysis of the mother revealed a karyotype (46,XX). Paternal karyotype analysis was not possible, so it could not be determined whether the deletion was inherited or occurred de novo. Several protein-coding genes mapped to the deleted region were identified.Conclusion: Most of the clinical manifestations observed in the patient are likely due to haploinsufficiency of the genes affected by the deletion on the short arm of chromosome 20. However, some malformations cannot be directly attributed to this phenomenon.