Wiedemann‑Steiner syndrome in a 2‑year‑old patient due to a rare nonsense KMT2A mutation of de novo origin: A case report

This is the authors' abstract. We don't add key points for this paper.

Wiedemann‑Steiner syndrome (WSS) is a genetic disorder characterized by a wide range of clinical symptoms, including developmental delay, intellectual disability, characteristic facial features, and other clinical features. It is part of group of disorders with an overlapping phenotypic spectrum known as chromatinopathies. WSS has been linked to heterozygous pathogenic mutations in the lysine methyltransferase 2A (KMT2A) gene that encodes a protein that is part of the epigenetic machinery. The present study reports the case of a 2‑year‑old female patient that presented with a variety of clinical features, including hypertelorism, thick eyebrows and epicanthus. Whole exome sequencing (WES) analysis was performed on the patient and the results revealed the presence of a rare heterozygous mutation in KMT2A, namely c.517C>T. The mutation was not detected in her parents, indicating that it occurred de novo in the patient. To the best of our knowledge, this is the first description of a patient with WSS due to the c.517C>T mutation. The present case report includes a detailed description of the phenotypic characteristics of the patient, which is crucial for genetic counseling in cases where this mutation is detected. Finally, the present study emphasizes the significance of utilizing WES for achieving differential diagnosis when a chromatinopathy is suspected.