[Clinical features and genetic analysis of a case of Wiedemann-Steiner syndrome due to variant of KMT2A gene].

OBJECTIVE

To explore the clinical features and genetic etiology of a child with Wiedemann-Steiner syndrome.

METHODS

A child with WSS who was admitted to the Hematology Department of Tianjin Children's Hospital in May 2021 was selected as the subject. Clinical data of the child was collected. Peripheral blood samples were collected from the child and his parents for the extraction of genomic DNA. The child was subjected to whole exome sequencing, and candidate variant was verified by Sanger sequencing of the child and his parents.

RESULTS

The main clinical features of the child have included pancytopenia, growth and mental retardation, and facial dysmorphism. Whole exome sequencing revealed that the child has harbored a heterozygous variant of the KMT2A gene, namely c.7804delA (p.M2602Cfs*39). Sanger sequencing verified the variant to be de novo in origin. The variant was unreported previously and predicted to be pathogenic based on the guidelines of American College of Medical Genetics and Genomics (PVS1+PS2+PM2).

CONCLUSION

The heterozygous c.7804delA (p.M2602Cfs*39) variant of the KMT2A gene probably underlay the WSS in this child. Above finding has enriched the mutational spectrum and clinical phenotypes of the KMT2A gene.