A novel de novo mutation (p.Pro1310Glnfs*46) in KMT2A caused Wiedemann-Steiner Syndrome in a Chinese boy with postnatal growth retardation: a case report.

Wiedemann-Steiner Syndrome (WSS) is a very rare autosomal dominant disease. Mutations in the KMT2A gene have been shown to cause this disease. A 1-year-old Chinese boy exhibited growth delay, psychomotor retardation, limb hypotonia and facial dysmorphism that was consistent with WSS. His body weight started to drop below the normal range at 3 months old, and the decline persisted. Whole-exome sequencing showed a novel de novo mutation (p.Pro1310Glnfs*46) in KMT2A, which confirmed the diagnosis of WSS. We diagnosed a Chinese boy who presented postnatal growth retardation with WSS caused by a novel de novo mutation in KMT2A. Our findings expand the mutational and phenotypic spectra of WSS and will be valuable for the mutation-based pre- and postnatal screening for and genetic diagnosis of WSS.