Hypotonia, Ataxia, and Delayed Development Syndrome caused by the EBF3 mutation in a Korean boy with muscle hypotonia

Hypotonia, Ataxia, and Delayed Development Syndrome (HADDS) is an autosomal-dominant, extremely rare neurodevelopmental disorder caused by the heterozygous EBF3 gene mutation.EBF3 is located on chromosome 10q26.3and acts as a transcription factor that regulates neurogenesis and differentiation.This syndrome is characterized by dysmorphism, cerebellar hypoplasia, urogenital anomaly, hypotonia, ataxia, intellectual deficit, and speech delay.The current report describes a 3-year-old Korean male carrying a de novo EBF3 mutation, c.589A>G (p.Asn197Asp), which was identified by whole exome sequencing.He manifested facial dysmorphism, hypotonia, strabismus, vermis hypoplasia, and urogenital anomalies, including vesicoureteral reflux, cryptorchidism, and areflexic bladder.This is the first report of a case of HADDS cause by an EBF3 mutation in the Korean population.